Search results for: fluid structure interaction (FSI)

Authors: Khalil Ur Rehman, M. Y. Malik, Usman Ali

Abstract:

In this paper, the problem proposed by Von Karman is treated in the attendance of additional flow field effects when the liquid is spaced above the rotating rigid disk. To be more specific, a purely viscous fluid flow yield by rotating rigid disk with Navier’s condition is considered in both magnetohydrodynamic and hydrodynamic frames. The rotating flow regime is manifested with heat source/sink and chemically reactive species. Moreover, the features of thermophoresis and Brownian motion are reported by considering nanofluid model. The flow field formulation is obtained mathematically in terms of high order differential equations. The reduced system of equations is solved numerically through self-coded computational algorithm. The pertinent outcomes are discussed systematically and provided through graphical and tabular practices. A simultaneous way of study makes this attempt attractive in this sense that the article contains dual framework and validation of results with existing work confirms the execution of self-coded algorithm for fluid flow regime over a rotating rigid disk.

Keywords: Navier’s condition, Newtonian fluid model, chemical reaction, heat source/sink

Procedia PDF Downloads 171

Authors: Prisa Damrongsiri, Kittinan Pongpianskul, Mario Kubek, Herwig Unger

Abstract:

Apps are today the most important possibility to adapt mobile phones and computers to fulfill the special needs of their users. Location- and context-sensitive programs are hereby the key to support the interaction of the user with his/her environment and also to avoid an overload with a plenty of dispensable information. The contribution shows, how a trusted, secure and really bi-directional communication and interaction among users and their environment can be established and used, e.g. in the field of home automation.

Keywords: apps, context-sensitive, location-sensitive, self-configuration, mobile computing, smart home

Procedia PDF Downloads 396

Authors: Nader H. Ghareeb, Mohamed S. Gaith, Sayed M. Soleimani

Abstract:

In modern engineering, weight optimization has a priority during the design of structures. However, optimizing the weight can result in lower stiffness and less internal damping, causing the structure to become excessively prone to vibration. To overcome this problem, active or smart materials are implemented. The coupled electromechanical properties of smart materials, used in the form of piezoelectric ceramics in this work, make these materials well-suited for being implemented as distributed sensors and actuators to control the structural response. The smart structure proposed in this paper is composed of a cantilevered steel beam, an adhesive or bonding layer, and a piezoelectric actuator. The static deflection of the structure is derived as function of the piezoelectric voltage, and the outcome is compared to theoretical and experimental results from literature. The relation between the voltage and the piezoelectric moment at both ends of the actuator is also investigated and a reduced finite element model of the smart structure is created and verified. Finally, a linear controller is implemented and its ability to attenuate the vibration due to the first natural frequency is demonstrated.

Keywords: active linear control, lyapunov stability theorem, piezoelectricity, smart structure, static deflection

Procedia PDF Downloads 387

Authors: Ali Raza, Rūta Rimašauskienė

Abstract:

In the current work, the fused deposition modelling (FDM) technique is used to manufacture PLA reinforced with carbon fibre composite structures with two unique layer patterns, 0°\0° and 0°\90°. The purpose of the study is to investigate the dynamic characteristics of each fabricated composite structure. The Macro Fiber Composite (MFC) is embedded with 0°/0° and 0°/90° structures to investigate the effect of an MFC (M8507-P2 type) patch on vibration amplitude suppression under dynamic loading circumstances. First, modal analysis testing was performed using a Polytec 3D laser vibrometer to identify bending mode shapes, natural frequencies, and vibration amplitudes at the corresponding natural frequencies. To determine the stiffness of each structure, several loads were applied at the free end of the structure, and the deformation was recorded using a laser displacement sensor. The findings confirm that a structure with 0°\0° layers pattern was found to have more stiffness compared to a 0°\90° structure. The maximum amplitude suppression in each structure was measured using a laser displacement sensor at the first resonant frequency when the control voltage signal with optimal phase was applied to the MFC. The results confirm that the 0°/0° pattern's structure exhibits a higher displacement reduction than the 0°/90° pattern. Moreover, stiffer structures have been found to perform amplitude suppression more effectively.

Keywords: carbon fibre composite, MFC, modal analysis stiffness, stiffness

Procedia PDF Downloads 63

Authors: Amanbek Jainakov, Abdikerim Kurbanaliev

Abstract:

The work presents the results of mathematical modeling of large-scale flows in areas with a complex topographic relief. The Reynolds-averaged Navier—Stokes equations constitute the basis of the three-dimensional unsteady modeling. The well-known Volume of Fluid method implemented in the solver interFoam of the open package OpenFOAM 2.3 is used to track the free-boundary location. The mathematical model adequacy is checked by comparing with experimental data. The efficiency of the applied technology is illustrated by the example of modeling the breakthrough of the dams of the Andijan (Uzbekistan) and Papan (near the Osh town, Kyrgyzstan) reservoir.

Keywords: three-dimensional modeling, free boundary, the volume-of-fluid method, dam break, flood, OpenFOAM

Procedia PDF Downloads 405

Authors: Nihan Akdemir

Abstract:

This research aims to investigate the role of fashion in the context of the deconstruction of gender stereotypes. Expectation of society and culture related to the biological structure of the individual corresponds to the gender. At this point there are some unseen rules which are given to person even from his/her childhoods according to the sex and gender, are called stereotypes. With basic example, girls should wear pink, and the boys should wear blue. Or boys do not wear skirt and the woman must behave like a woman. There are also many many stereotypes like them. But the clothing style the individual uses to express his or her gender identity may not match the expectations of the community and society. In the context of big role of the clothing, these stereotypes could be deconstructed because clothes are the visible expression of gender identity of the person. And fashion is a big part of this structure because fashion is a pioneer of what people wear in other words fashion tells to people what should they wear this season. Nowadays fashion has also meant about expressing identity independent of whether you were born male or female. Many fashion brands prepare their collections in the concept of ‘gender fluid’ by deconstructions. It means that fashion is opening the roads for being more free about the gender identity. The representations of gender fluidity through fashion help bring a sense of normality to people who are trying to find the self-confidence to express who they want to be. Maybe the voice of the streets carries this point to the catwalks firstly, and then it becomes a trend. All these items have been explained with visual images and supported by the literature investigations. And the results are showed that the numbers of collections about it are increasing and fashion sector takes this issue into consideration. And this new approach reached to the streets.

Keywords: fashion, gender identity, gender stereotypes, trend

Procedia PDF Downloads 473

Authors: P. Naderi, M. N. Ouarzazi, S. C. Hirata, H. Ben Hamed, H. Beji

Abstract:

The stability of mixed convection in a Newtonian fluid medium heated from below and cooled from above, also known as the Poiseuille-Rayleigh-Bénard problem, has been extensively investigated in the past decades. To our knowledge, mixed convection in porous media has received much less attention in the published literature. The present paper extends the mixed convection problem in porous media for the case of a viscoelastic fluid flow owing to its numerous environmental and industrial applications such as the extrusion of polymer fluids, solidification of liquid crystals, suspension solutions and petroleum activities. Without a superimposed through-flow, the natural convection problem of a viscoelastic fluid in a saturated porous medium has already been treated. The effects of the viscoelastic properties of the fluid on the linear and nonlinear dynamics of the thermoconvective instabilities have also been treated in this work. Consequently, the elasticity of the fluid can lead either to a Hopf bifurcation, giving rise to oscillatory structures in the strongly elastic regime, or to a stationary bifurcation in the weakly elastic regime. The objective of this work is to examine the influence of the main horizontal flow on the linear and characteristics of these two types of instabilities. Under the Boussinesq approximation and Darcy's law extended to a viscoelastic fluid, a temporal stability approach shows that the conditions for the appearance of longitudinal rolls are identical to those found in the absence of through-flow. For the general three-dimensional (3D) perturbations, a Squire transformation allows the deduction of the complex frequencies associated with the 3D problem using those obtained by solving the two-dimensional one. The numerical resolution of the eigenvalue problem concludes that the through-flow has a destabilizing effect and selects a convective configuration organized in purely transversal rolls which oscillate in time and propagate in the direction of the main flow. In addition, by using the mathematical formalism of absolute and convective instabilities, we study the nature of unstable three-dimensional disturbances. It is shown that for a non-vanishing through-flow, general three-dimensional instabilities are convectively unstable which means that in the absence of a continuous noise source these instabilities are drifted outside the porous medium, and no long-term pattern is observed. In contrast, purely transversal rolls may exhibit a transition to absolute instability regime and therefore affect the porous medium everywhere including in the absence of a noise source. The absolute instability threshold, the frequency and the wave number associated with purely transversal rolls are determined as a function of the Péclet number and the viscoelastic parameters. Results are discussed and compared to those obtained from laboratory experiments in the case of Newtonian fluids.

Keywords: instability, mixed convection, porous media, and viscoelastic fluid

Procedia PDF Downloads 341

Authors: Ehsan Sadie

Abstract:

Developments in the field of damping technology and advances in the area of dampers in equipping many structures have been the result of efforts and testing by researchers in this field. In this paper, a sample of a two-story building is simulated with the help of SAP2000 software, and the effect of a viscous damper on the performance of the structure is explained. The effect of dampers on the response of the structure is investigated. This response involves the horizontal displacement of floors. In this case, the structure is modeled once without a damper and again with a damper. In this regard, the results are presented in the form of tables and graphs. Since the seismic behavior of the structure is studied, the responses show the appropriate effect of viscous dampers in reducing the displacement of floors, and also the energy dissipation in the structure with dampers compared to structures without dampers is significant. Therefore, it is economical to use viscous dampers in areas that have a higher relative earthquake risk.

Keywords: bending frame, displacement criterion, dynamic response spectra, earthquake, non-linear history spectrum, SAP2000 software, structural response, viscous damper

Procedia PDF Downloads 116

Authors: Monika Konieczyńska, Joanna Fajfer, Olga Lipińska

Abstract:

In Poland works related to the exploration and prospection of unconventional hydrocarbons (natural gas accumulated in the Silurian shale formations) started in 2007, based on the experience of the other countries that have created new possibilities for the use of existing hydrocarbons resources. The highly water-consuming process of hydraulic fracturing is required for the exploitation of shale gas which implies a need to ensure large volume of water available. As a result considerable amount of mining waste is generated, particularly liquid waste, i.e. flowback fluid with variable chemical composition. The chemical composition of the flowback fluid depends on the composition of the fracturing fluid and the chemistry of the fractured geological formations. Typically, flowback fluid is highly salinated, can be enriched in heavy metals, including rare earth elements, naturally occurring radioactive materials and organic compounds. The generated fluids considered as the extractive waste should be properly managed in the recovery or disposal facility. Problematic issue is both high hydration of waste as well as their variable chemical composition. Also the limited capacity of currently operating facilities is a growing problem. Based on the estimates, currently operating facilities will not be sufficient for the need of waste disposal when extraction of unconventional hydrocarbons starts. Further more, the content of metals in flowback fluids including rare earth elements is a considerable incentive to develop technology of metals recovery. Also recycling is a key factor in terms of selection of treatment process, which should provide that the thresholds required for reuse are met. The paper will present the study of the flowback fluids chemical composition, based on samples from hydraulic fracturing processes performed in Poland. The scheme of flowback fluid cleaning and recovering technology will be reviewed along with a discussion of the results and an assessment of environmental impact, including all generated by-products. The presented technology is innovative due to the metal recovery, as well as purified water supply for hydraulic fracturing process, which is significant contribution to reducing water consumption.

Keywords: environmental impact, flowback fluid, management of special waste streams, metals recovery, shale gas

Procedia PDF Downloads 262

Authors: Varun Dongre, Stefan Pirker, Stefan Heinrich

Abstract:

Over the last decades, the numerical modelling of fluidized bed processes has become feasible even for industrial processes. Commonly, continuous two-fluid models are applied to describe large-scale fluidization. In order to allow for coarse grids novel two-fluid models account for unresolved sub-grid heterogeneities. However, computational efforts remain high – in the order of several hours of compute-time for a few seconds of real-time – thus preventing the representation of long-term phenomena such as heating or particle conversion processes. In order to overcome this limitation, data-based recurrence computational fluid dynamics (rCFD) has been put forward in recent years. rCFD can be regarded as a data-based method that relies on the numerical predictions of a conventional short-term simulation. This data is stored in a database and then used by rCFD to efficiently time-extrapolate the flow behavior in high spatial resolution. This study will compare the numerical predictions of rCFD simulations with those of corresponding full CFD reference simulations for lab-scale and pilot-scale fluidized beds. In assessing the predictive capabilities of rCFD simulations, we focus on solid mixing and secondary gas holdup. We observed that predictions made by rCFD simulations are highly sensitive to numerical parameters such as diffusivity associated with face swaps. We achieved a computational speed-up of four orders of magnitude (10,000 time faster than classical TFM simulation) eventually allowing for real-time simulations of fluidized beds. In the next step, we apply the checkerboarding technique by introducing gas tracers subjected to convection and diffusion. We then analyze the concentration profiles by observing mixing, transport of gas tracers, insights about the convective and diffusive pattern of the gas tracers, and further towards heat and mass transfer methods. Finally, we run rCFD simulations and calibrate them with numerical and physical parameters compared with convectional Two-fluid model (full CFD) simulation. As a result, this study gives a clear indication of the applicability, predictive capabilities, and existing limitations of rCFD in the realm of fluidization modelling.

Keywords: multiphase flow, recurrence CFD, two-fluid model, industrial processes

Procedia PDF Downloads 75

Authors: Shogo Kato, Daisuke Okamoto, Satoko Tsuru, Yoshinori Iizuka, Ryoko Shimono

Abstract:

Healthcare safety has been perceived important. It is essential to prevent troubles in healthcare processes for healthcare safety. Trouble prevention is based on trouble prediction using accumulated knowledge on processes, troubles, and countermeasures. However, information on troubles has not been accumulated in hospitals in the appropriate structure, and it has not been utilized effectively to prevent troubles. In the previous study, though a detailed knowledge acquisition process for trouble prediction was proposed, the knowledgebase for countermeasures was not involved. In this paper, we aim to propose the structure of the knowledgebase for countermeasures in the knowledge acquisition process for trouble prediction in healthcare process. We first design the structure of countermeasures and propose the knowledge representation form on countermeasures. Then, we evaluate the validity of the proposal, by applying it into an actual hospital.

Keywords: trouble prevention, knowledge structure, structured knowledge, reusable knowledge

Procedia PDF Downloads 367

Authors: Mohamed Abdelmounim Bakkali, Mustapha El Mataouy, Abellatif Aaliti, Mouhamed Khaddor

Abstract:

In the paper, we study the effects of introducing hafnium oxide on Raman spectra of silica glass planar waveguide activated by 0.3 mol% Er3+ ions. This work compares Raman spectra measured for three thin films deposited on silicon substrate. The films were prepared with different molar ratio of Si/Hf using sol-gel method and deposited by dip coating technique. The effect of hafnium oxide incorporation on the waveguides shows the evolution of the structure of this material. This structural information is useful to understand the luminescence intensity by means of ion–ion interaction mechanisms.

Keywords: optical amplifiers, non-bridging oxygen, erbium, sol-gel, waveguide, silica-hafnia

Procedia PDF Downloads 307

Authors: Binyam Teferi

Abstract:

Numerical and theoretical analysis of mixed convection flow of magneto- hydrodynamics micropolar fluid with stretching capillary in the presence of thermal radiation, chemical reaction, viscous dissipation, and heat generation/ absorption have been studied. The non-linear partial differential equations of momentum, angular velocity, energy, and concentration are converted into ordinary differential equations using similarity transformations which can be solved numerically. The dimensionless governing equations are solved by using Runge Kutta fourth and fifth order along with the shooting method. The effect of physical parameters viz., micropolar parameter, unsteadiness parameter, thermal buoyancy parameter, concentration buoyancy parameter, Hartmann number, spin gradient viscosity parameter, microinertial density parameter, thermal radiation parameter, Prandtl number, Eckert number, heat generation or absorption parameter, Schmidt number and chemical reaction parameter on flow variables viz., the velocity of the micropolar fluid, microrotation, temperature, and concentration has been analyzed and discussed graphically. MATLAB code is used to analyze numerical and theoretical facts. From the simulation study, it can be concluded that an increment of micropolar parameter, Hartmann number, unsteadiness parameter, thermal and concentration buoyancy parameter results in decrement of velocity flow of micropolar fluid; microrotation of micropolar fluid decreases with an increment of micropolar parameter, unsteadiness parameter, microinertial density parameter, and spin gradient viscosity parameter; temperature profile of micropolar fluid decreases with an increment of thermal radiation parameter, Prandtl number, micropolar parameter, unsteadiness parameter, heat absorption, and viscous dissipation parameter; concentration of micropolar fluid decreases as unsteadiness parameter, Schmidt number and chemical reaction parameter increases. Furthermore, computational values of local skin friction coefficient, local wall coupled coefficient, local Nusselt number, and local Sherwood number for different values of parameters have been investigated. In this paper, the following important results are obtained; An increment of micropolar parameter and Hartmann number results in a decrement of velocity flow of micropolar fluid. Microrotation decreases with an increment of the microinertial density parameter. Temperature decreases with an increasing value of the thermal radiation parameter and viscous dissipation parameter. Concentration decreases as the values of Schmidt number and chemical reaction parameter increases. The coefficient of local skin friction is enhanced with an increase in values of both the unsteadiness parameter and micropolar parameter. Increasing values of unsteadiness parameter and micropolar parameter results in an increment of the local couple stress. An increment of values of unsteadiness parameter and thermal radiation parameter results in an increment of the rate of heat transfer. As the values of Schmidt number and unsteadiness parameter increases, Sherwood number decreases.

Keywords: thermal radiation, chemical reaction, viscous dissipation, heat absorption/ generation, similarity transformation

Procedia PDF Downloads 129

Authors: Nony Rahadiva

Abstract:

The development of housing in urban areas can not be separated from the high rate of population growth from both natural population growth and population growth due to migration. The development is bounded by urban land area so that construction of flats become a development priority. Quality of residential flats are influenced by the patterns of behavior of its inhabitants. The frequency of contact between the occupants become one of the effects of good social relations, but harmful activity can degrade the environment, especially in flats. One of the social relationships that can be seen on the flats development is the residents in Kutobedah flat built in Malang city. Problems that occur in that place is unfavorable flat management due to social activities such as daily activities and also the neighboring activities of apartment dwellers who tend not to pay attention to the environment. Based on these problems we can do a study on social interaction in Kutobedah flat and its influence on the management of flat facilities and infrastructures. This research was carried out by submitting a questionnaire to the residents of the apartment based social activities , operations and maintenance of the flats. By using a weighted analysis, we can find that social interaction tenants is high, but the level of infrastructure and facilities management of the tenants is low so it is needed to counsel the residents how to use and maintain the infrastructure properly.

Keywords: activities, flat, infrastructure management, social interaction

Procedia PDF Downloads 432

Authors: H. Pasternak, T. Krausche

Abstract:

The Porsche Pavilion is an innovative stainless steel construction using the principle, often used in ship and car design, as an advantage for building a light but stiff structure. The Pavilion is a one of a kind and outstanding construction that you can find. It fits right in the existing parts of the Autostadt within the lagoon landscape and was built in only eight months. With its curving lines and exiting bends the structure is an extraordinary work which was designed by Henn architects, Munich. The monocoque has a good balance between material and support structure. The stiffness is achieved by the upper and lower side sheathing plates and the intermediate formers. Also the roof shell has no joints and a smooth surface. The assembling of the structure requires a large time and effort cost due to many welds which are necessary to connect all section to one large shell.

Keywords: construction welding, exhibition building, light steel construction, monocoque

Procedia PDF Downloads 523

Authors: Elias Akoury

Abstract:

Nuclear Magnetic Resonance (NMR) spectroscopy is an indispensable technique used in structure determination of small and macromolecules to study their physical properties, elucidation of characteristic interactions, dynamics and thermodynamic processes. Quantum mechanics defines the theoretical description of NMR spectroscopy and treatment of the dynamics of nuclear spin systems. The phenomenon of residual dipolar coupling (RDCs) has become a routine tool for accurate structure determination by providing global orientation information of magnetic dipole-dipole interaction vectors within a common reference frame. This offers accessibility of distance-independent angular information and insights to local relaxation. The measurement of RDCs requires an anisotropic orientation medium for the molecules to partially align along the magnetic field. This can be achieved by introduction of liquid crystals or attaching a paramagnetic center. Although anisotropic paramagnetic tags continue to mark achievements in the biomolecular NMR of large proteins, its application in small organic molecules remains unspread. Here, we propose a strategy for the synthesis of a lanthanide tag and the measurement of RDCs in organic molecules using paramagnetic lanthanide complexes.

Keywords: lanthanide tags, NMR spectroscopy, residual dipolar coupling, quantum mechanics of spin dynamics

Procedia PDF Downloads 188

Authors: K. Jafar, R. Nazar, A. Ishak, I. Pop

Abstract:

The present analysis considers the steady stagnation point flow and heat transfer towards a permeable sheet in an upper-convected Maxwell (UCM) electrically conducting fluid, with a constant magnetic field applied in the transverse direction to flow, and a local heat generation within the boundary layer with a heat generation rate proportional to (T-T_inf)^p. Using a similarity transformation, the governing system of partial differential equations is first transformed into a system of ordinary differential equations, which is then solved numerically using a finite-difference scheme known as the Keller-box method. Numerical results are obtained for the flow and thermal fields for various values of the shrinking/stretching parameter lambda, the magnetic parameter M, the elastic parameter K, the Prandtl number Pr, the suction parameter s, the heat generation parameter Q, and the exponent p. The results indicate the existence of dual solutions for the shrinking sheet up to a critical value lambda_c whose value depends on the value of M, K, and s. In the presence of internal heat absorbtion (Q<0), the surface heat transfer rate decreases with increasing p but increases with parameter Q and s, when the sheet is either stretched or shrunk.

Keywords: magnetohydrodynamic (MHD), boundary layer flow, UCM fluid, stagnation point, shrinking sheet

Procedia PDF Downloads 354

Authors: Bamikole J. Adeyemi, Prashant Jadhawar, Lateef Akanji

Abstract:

Theoretically, there exist two mathematical interfaces (fluid-solid and fluid-fluid) when a liquid film is present on solid surfaces. These interfaces overlap if the mineral surface is oil-wet or mixed wet, and therefore, the effects of disjoining pressure are significant on both boundaries. Hence, dewetting is a necessary process that could detach oil from the mineral surface. However, if the thickness of the thin water film directly in contact with the surface is large enough, disjoining pressure can be thought to be zero at the liquid-liquid interface. Recent studies show that the integration of fluid-fluid interactions with fluid-rock interactions is an important step towards a holistic approach to understanding smart water effects. Experiments have shown that the brine solution can alter the micro forces at oil-water interfaces, and these ion-specific interactions lead to oil emulsion formation. The natural emulsifiers present in crude oil behave as polyelectrolytes when the oil interfaces with low salinity water. Wettability alteration caused by low salinity waterflooding during Enhanced Oil Recovery (EOR) process results from the activities of divalent ions. However, polyelectrolytes are said to lose their viscoelastic property with increasing cation concentrations. In this work, the influence of cation concentrations on the dynamics of viscoelastic liquid-liquid interfaces is numerically investigated. The resultant ion concentrations at the crude oil/brine interfaces were estimated using a surface complexation model. Subsequently, the ion concentration parameter is integrated into a mathematical model to describe its effects on the dynamics of a viscoelastic interfacial thin film. The film growth, stability, and rupture were measured after different time steps for three types of fluids (Newtonian, purely elastic and viscoelastic fluids). The interfacial films respond to exposure time in a similar manner with an increasing growth rate, which resulted in the formation of more droplets with time. Increased surfactant accumulation at the interface results in a higher film growth rate which leads to instability and subsequent formation of more satellite droplets. Purely elastic and viscoelastic properties limit film growth rate and consequent film stability compared to the Newtonian fluid. Therefore, low salinity and reduced concentration of the potential determining ions in injection water will lead to improved interfacial viscoelasticity.

Keywords: liquid-liquid interfaces, surfactant concentrations, potential determining ions, residual oil mobilization

Procedia PDF Downloads 144

Authors: Baha-Aldeen S. Algmati, Ahmed R. Ballil

Abstract:

Multiphase flows occur widely in many engineering and industrial processes as well as in the environment we live in. In particular, bubbly flows are considered to be crucial phenomena in fluid flow applications and can be studied and analyzed experimentally, analytically, and computationally. In the present paper, the dynamic motion of an air bubble rising within a column of liquid is numerically simulated using an open-source CFD modeling tool 'OpenFOAM'. An interface tracking numerical algorithm called MULES algorithm, which is built-in OpenFOAM, is chosen to solve an appropriate mathematical model based on the volume of fluid (VOF) numerical method. The bubbles initially have a spherical shape and starting from rest in the stagnant column of liquid. The algorithm is initially verified against numerical results and is also validated against available experimental data. The comparison revealed that this algorithm provides results that are in a very good agreement with the 2D numerical data of other CFD codes. Also, the results of the bubble shape and terminal velocity obtained from the 3D numerical simulation showed a very good qualitative and quantitative agreement with the experimental data. The simulated rising bubbles yield a very small percentage of error in the bubble terminal velocity compared with the experimental data. The obtained results prove the capability of OpenFOAM as a powerful tool to predict the behavior of rising characteristics of the spherical bubbles in the stagnant column of liquid. This will pave the way for a deeper understanding of the phenomenon of the rise of bubbles in liquids.

Keywords: CFD simulations, multiphase flows, OpenFOAM, rise of bubble, volume of fluid method, VOF

Procedia PDF Downloads 124

Authors: Kwasi Dartey-Baah, Mias De Klerk

Abstract:

Project complexity has been cited as one of the essential areas of project management. It can be observed from environmental, social, technological, and organisational viewpoints, and its handling is critical to project success. Conceptualised in varied industries, this paper seeks to ascertain the meaning and understanding of project complexity within the Ghanaian construction industry based on the three dimensions of complexities (faith, fact, and interaction) using experts' opinions. Taking the form of a focus group discussion, the paper sought to gain an in-depth understanding of project complexity issues in Ghana’s construction industry. The method use obtained data from experts (a purposely selected group) comprising project leaders and project management academics. The findings indicated that the experts broadly agreed with the complexity items but offered varied reasons for their agreement. In the composite assessment of the complexity dimensions of (faith, fact, and interaction), it emerged that there was some agreement with the complexity dimensions of fact and interaction within Ghana’s construction industry. On the other hand, with the dimension for complexity by faith, it was noted that the experts in Ghana’s construction construed complexity by faith, not as the absence of evidence but the evidence that hinges on at least a member of the project team. It is expected that other researches on project complexity will focus on other industries to enhance the knowledge of the same within the field of project management.

Keywords: project complexity, complexity by faith, complexity by fact, complexity by interaction, construction industry, Ghana

Procedia PDF Downloads 161

Authors: Myeong-Gon Lee, Yang-Gyun Kim, Tae-Young Kim, Seung-Ho Han

Abstract:

The high-pressure valve uses one set of 2-way valves for the purpose of reversing fluid direction. If there is no accurate control device for the 2-way valves, lots of surging can be generated. The surging is a kind of pressure ripple that occurs in rapid changes of fluid motions under inaccurate valve control. To reduce the surging effect, a 3-way reversing valve can be applied which provides a rapid and precise change of water flow directions without any accurate valve control system. However, a cavitation occurs due to a complicated internal trim shape of the 3-way reversing valve. The cavitation causes not only noise and vibration but also decreasing the efficiency of valve-operation, in which the bubbles generated below the saturated vapor pressure are collapsed rapidly at higher pressure zone. The shape optimization of the 3-way reversing valve to minimize the cavitation effect is necessary. In this study, the cavitation index according to the international standard ISA was introduced to estimate macroscopically the occurrence of the cavitation effect. Computational fluid dynamic analysis was carried out, and the cavitation effect was quantified by means of the percent of cavitation converted from calculated results of vapor volume fraction. In addition, the shape optimization of the 3-way reversing valve was performed by taking into account of the percent of cavitation.

Keywords: 3-Way reversing valve, cavitation, shape optimization, vapor volume fraction

Procedia PDF Downloads 371

Authors: Ali Abdul Kadhim, Fue Lien

Abstract:

Solid particle distribution on an impingement surface has been simulated utilizing a graphical processing unit (GPU). In-house computational fluid dynamics (CFD) code has been developed to investigate a 3D turbulent impinging jet using the lattice Boltzmann method (LBM) in conjunction with large eddy simulation (LES) and the multiple relaxation time (MRT) models. This paper proposed an improvement in the LBM-cellular automata (LBM-CA) probabilistic method. In the current model, the fluid flow utilizes the D3Q19 lattice, while the particle model employs the D3Q27 lattice. The particle numbers are defined at the same regular LBM nodes, and transport of particles from one node to its neighboring nodes are determined in accordance with the particle bulk density and velocity by considering all the external forces. The previous models distribute particles at each time step without considering the local velocity and the number of particles at each node. The present model overcomes the deficiencies of the previous LBM-CA models and, therefore, can better capture the dynamic interaction between particles and the surrounding turbulent flow field. Despite the increasing popularity of LBM-MRT-CA model in simulating complex multiphase fluid flows, this approach is still expensive in term of memory size and computational time required to perform 3D simulations. To improve the throughput of each simulation, a single GeForce GTX TITAN X GPU is used in the present work. The CUDA parallel programming platform and the CuRAND library are utilized to form an efficient LBM-CA algorithm. The methodology was first validated against a benchmark test case involving particle deposition on a square cylinder confined in a duct. The flow was unsteady and laminar at Re=200 (Re is the Reynolds number), and simulations were conducted for different Stokes numbers. The present LBM solutions agree well with other results available in the open literature. The GPU code was then used to simulate the particle transport and deposition in a turbulent impinging jet at Re=10,000. The simulations were conducted for L/D=2,4 and 6, where L is the nozzle-to-surface distance and D is the jet diameter. The effect of changing the Stokes number on the particle deposition profile was studied at different L/D ratios. For comparative studies, another in-house serial CPU code was also developed, coupling LBM with the classical Lagrangian particle dispersion model. Agreement between results obtained with LBM-CA and LBM-Lagrangian models and the experimental data is generally good. The present GPU approach achieves a speedup ratio of about 350 against the serial code running on a single CPU.

Keywords: CUDA, GPU parallel programming, LES, lattice Boltzmann method, MRT, multi-phase flow, probabilistic model

Procedia PDF Downloads 207

Authors: Seyed Abolhasan Naeini, Mohammad Hossein Zade, E. Izadi, M. Hossein Zade

Abstract:

The different seismic behavior of liquid storage tanks rather than conventional structures makes their responses more complicated. Uplifting and excessive settlement due to liquid sloshing are the most frequent damages in cylindrical liquid tanks after shell bucking failure modes. As a matter of fact, uses of liquid storage tanks because of the simple construction on compact layer of soil as a foundation are very conventional, but in some cases need to retrofit are essential. The tank seismic behavior can be improved by modifying dynamic characteristic of tank with verifying seismic loads as well as retrofitting and improving base ground. This paper focuses on a typical steel tank on loose, medium and stiff sandy soil and describes an evaluation of displacement of the tank before and after retrofitting. The Abaqus program was selected for its ability to include shell and structural steel elements, soil-structure interaction, and geometrical nonlinearities and contact type elements. The result shows considerable decreasing in settlement and uplifting in the case of retrofitted tank. Also, by increasing shear strength parameter of soil, the performance of the liquid storage tank under the case of seismic load increased.

Keywords: steel tank, soil-structure, sandy soil, seismic load

Procedia PDF Downloads 420

Authors: Nathasa Mazna Ramli, Nurul Husna Mohd Salleh, Nurul Aini Muhamed

Abstract:

This study focuses on the governance of an Islamic philanthropic institution in Malaysia. Specifically, the internal governance structure of corporate Islamic endowment, or waqf, is being analysed. The purposes of waqf are to provide continuous charity that could generate perpetual income flow for the needy. This study is based on the principle of MCCG 2012, Shariah Governance Framework and charity governance. This study utilises publicly available data to examine the internal governance structure of a corporate waqf. This study finds that the Islamic philanthropic Institution practices, to some extent, have a sound governance structure to discharge their transparency and accountability. Furthermore, findings also showed that though governance structure is in place, most of the structures are not disclosed in the annual reports of the company. Findings from the study could extend the knowledge in these areas and stimulate further research on the governance of Islamic philanthropic institutions, particularly for corporate waqf.

Keywords: accountability, governance, Islamic philanthropic, corporate waqf

Procedia PDF Downloads 566

Authors: Ammar Alsabery, Habibis Saleh, Norazam Arbin, Ishak Hashim

Abstract:

Unsteady natural convection and heat transfer in a square cavity partially filled with porous media using a thermal non-equilibrium model is studied in this paper. The left vertical wall is maintained at a constant hot temperature and the right vertical wall is maintained at a constant cold temperature, while the horizontal walls are adiabatic. The governing equations are obtained by applying the Darcy model and Boussinesq approximation. COMSOL's finite element method is used to solve the non-dimensional governing equations together with specified boundary conditions. The governing parameters of this study are the Rayleigh number, the modified thermal conductivity ratio, the inter-phase heat transfer coefficien and the time independent. The results presented for values of the governing parameters in terms of streamlines in both fluid/porous layer, isotherms of fluid and solid porous layer, isotherms of fluid layer, and average Nusselt number.

Keywords: unsteady natural convection, thermal non-equilibrium model, Darcy model

Procedia PDF Downloads 376

Authors: Ryoo Hye Jin Agnes

Abstract:

This study aims to investigate the efficacy of clickers in fostering L2 class interaction. In an L2 classroom, active learner-to-learner interactions and learner-to-teacher interactions play an important role in language acquisition. In light of this, introducing learning tools that promote such interactions would benefit L2 classroom by fostering interaction. This is because the anonymity of clickers allows learners to express their needs without the social risks associated with speaking up in the class. clickers therefore efficiently help learners express their level of understanding during the process of learning itself. This allows for an evaluative feedback loop where both learners and teachers understand the level of progress of the learners, better enabling classrooms to adapt to the learners’ needs. Eventually this tool promotes participation from learners. This, in turn, is believed to be effective in fostering classroom interaction, allowing learning to take place in a more comfortable yet vibrant way. This study is finalized by presenting the result of an experiment conducted to verify the effectiveness of this approach when teaching pragmatic aspect of Korean expressions with similar semantic functions. The learning achievement of learners in the experimental group was found higher than the learners’ in a control group. A survey was distributed to the learners, questioning them regarding the efficacy of clickers, and how it contributed to their learning in areas such as motivation, self-assessment, increasing participation, as well as giving feedback to teachers. Analyzing the data collected from the questionnaire given to the learners, the study presented data suggesting that this approach increased the scope of interactivity in the classroom, thus not only increasing participation but enhancing the type of classroom participation among learners. This participation in turn led to a marked improvement in their communicative abilities.

Keywords: second language acquisition, interaction, clickers, learner response system, output from learners, learner’s cognitive process

Procedia PDF Downloads 521

Authors: Jinshuo Zhang

Abstract:

Lucid dreams(LD) are the mental states in which people are aware that they are dreaming, which is a rising interdisciplinary topic among psychologists, neuroscientists and spiritual practitioners. From a phenomenological perspective, this research explores the self-consciousness structure in lucid dreams, particularly focusing on the self-reference structure between lucidity(the observer) and the dream ego(the observed). The main argument of this paper is that the self-structure in lucid dreams is a single-level paradigm. In this paper, the phenomenological characteristics of lucidity in LD are carefully unfolded. The appearance of lucidity is the most significant part of understanding the self-structure and the consciousness in dreams, which is also related to the “Six Bardos practices” in Tibetan Buddhism. In the second section, this research investigates the referential relationship between"lucidity" and "the dream ego" using the phenomenological resource of subjectivity theory, as well as referring to many cases in the psychological labs. Despite the appearance of various consciousness layers in lucid dreams, according to this paper, they are all part of a single-level consciousness paradigm. Dream ego is transparent, and dream lucidity can grasp it directly and thoroughly during LD. This research also responds to some potential criticisms and engages in current debates about the self-structure issue in lucid dreams, as well as discussing some future research prospects for dreams and lucid dreams.

Keywords: lucid dream, self-awareness, phenomenological perspective, high-order theory, one-level consciousness

Procedia PDF Downloads 99

Authors: Karine B. de Oliveira, Carina F. Dorneles

Abstract:

The structure level matching is the problem of combining elements of a structure, which can be represented as entities, classes, XML elements, web forms, and so on. This is a challenge due to large number of distinct representations of semantically similar structures. This paper describes a structure-based matching method applied to search for different representations in data sources, considering the similarity between elements of two structures and the data source context. Using real data sources, we have conducted an experimental study comparing our approach with our baseline implementation and with another important schema matching approach. We demonstrate that our proposal reaches higher precision than the baseline.

Keywords: context, data source, index, matching, search, similarity, structure

Procedia PDF Downloads 364

Authors: Hanan A. Abdulhameed, Huda Y. Alyami

Abstract:

The study presents a new international direction to conduct collaborative educational research. It follows a qualitative and quantitative methodology in investigating the main requirements to build an e-platform for Virtual Research Teams (VRTs). The e-platform considers three main components: First, the human and cultural structure, second, the institutional/organizational structure, and third, the technological structure. The study mainly focuses on the third component, the technological structure (the e-platform), and studies how to incorporate the other components: The human/cultural structure and the institutional/organizational structure in order to build an effective e-platform. The importance of the study is that it presents a comprehensive study about VRTs in terms of definition, types, structure, and main challenges. In addition, it suggests a practical way that benefits from the information and communication technology to conduct collaborative educational research by building and managing virtual research teams through an effective e-platform. The study draws the main framework to build an e-platform for collaborative educational research teams in Arab World. Thus, it tackles mainly the theoretical aspects, the framework of an effective e-platform. Then, it presents the evaluation of 18 Arab educational experts' to the proposed e-platform.

Keywords: collaborative research, educational science, E-platform, social research networks sites (SRNS), virtual research teams (VRTs)

Procedia PDF Downloads 460

Authors: Hasn Perera, Is Almeida, Hnk Perera, Mzf Mohammed, Ade Silva, H. Wijesinghe, Ajal Fernando

Abstract:

Introduction: Dengue is a major Public Health burden of two clinical entities, Dengue Fever & Dengue Haemorrhagic Fever (DHF). The vast majority of dengue deaths occur in DHF patients, where the diagnosis hinges on the presence of fluid leakage. Limited Ultrasound Scans (USS) of chest and abdomen are used widely at Centre for Clinical Management of Dengue & Dengue Haemorrhagic Fever (CCMDDHF), as the primary method for detecting fluid leaking in DHF. This study analyses the relationship between haematological and USS findings at the onset of leaking and to further determine the usefulness of ultrasound in diagnosing DHF. Methods: A prospective analysis of 80 serologically confirmed dengue patients initially admitted to a General Medical and Paediatric wards who were subsequently transferred to the CCMDDHF from March to September 2017 were analysed. In addition to repeated blood counts and capillary haematocrits’, serial USS were done to detect the onset fluid leaking by three competent and experienced doctors at CCMDDHF. Results: 80 patients (male: female: 38:42) with a mean age of 20 years (SD ±16.8, range 3-74) were evaluated. Dropping of platelet counts below 100,000 and haematocrit rise towards 20% started 4±1.3 day of fever with a mean platelet value of 69x103(range17-98x103). Gallbladder wall thickening was the commonest (98.7%) USS finding followed by fluid in hepato-renal pouch (95%), pelvic fluid (58.7%), right-sided pleural effusion (35%), bilateral effusions (7.5%). USS evidence of plasma leakage was detected in 11.25 %( n=9) of DHF cases from 1 day before significant haematocrit rise was noted. 35 (43.7%) patients with lowering platelets and haematocrit rise showed no objective evidence of plasma leaking on ultrasound scan. Conclusion: This outbreak underscores the importance of USS as a useful, sensitive and cost-effective tool for early diagnosis of suspected DHF cases, facilitating the tracking of progress of leaking and management of epidemics.

Keywords: dengue, ultrasound, plasma leaking, South Asia

Procedia PDF Downloads 234