Search results for: flow capacity (Cv)

Authors: Chaitanya R. Mali, V. Vinod, Ashwin W. Patwardhan

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Design of long vertical steam generator (SG) tubes in nuclear power plant involves an understanding of different aspects of flow boiling phenomenon such as flow instabilities, flow regimes, dry out, critical heat flux, pressure drop, etc. The knowledge of the prediction of local thermal hydraulic characteristics is necessary to understand these aspects. For this purpose, the methodology has been developed which covers all the flow boiling regimes to model full range flow boiling phenomenon. In this methodology, the vertical tube is divided into four sections based on vapor fraction value at the end of each section. Different modeling strategies have been applied to the different sections of the vertical tube. Computational fluid dynamics simulations have been performed on a vertical SG tube of 0.0126 m inner diameter and 23 m length. The thermal hydraulic parameters such as vapor fraction, liquid temperature, heat transfer coefficient, pressure drop, heat flux distribution have been analyzed for different designed heat duties (1.1 MW (20%) to 3.3 MW (60%)) and flow conditions (10 % to 80 %). The sensitivity of different boiling parameters such as bubble departure diameter, nucleation site density, bubble departure frequency on the thermal hydraulic parameters was also studied. Flow instability has been observed at 20 % designed heat duty and 20 % flow conditions.

Keywords: thermal hydraulics, boiling, vapor fraction, sensitivity

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Authors: Valentina Alessandra Carvalho do Vale, Elmo Thiago Lins Cöuras Ford

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In view of the requirements of the current industrial processes, the instrumentation plays a critical role. In this context, this work aims to raise some the operating characteristics of the level and flow transmitters, in addition to observing their similarities and possible limitations for certain configurations.

Keywords: flow, level, instrumentation, configurations of meters, method of choice of the meters, instrumentation in the industrial processes

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Authors: Robin Molinier

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Industrial symbiosis (I.S) deals with both substitution synergies (exchange of waste materials, fatal energy and utilities as resources for production) and infrastructure/service sharing synergies. The latter is based on the intensification of use of an asset and thus requires to balance capital costs increments with snowball effects (network externalities) for its implementation. Initial investors must specify ex-ante arrangements (cost sharing and pricing schedule) to commit toward investments in capacities and transactions. Our model investigate the decision of 2 actors trying to choose cooperatively a level of infrastructure capacity oversizing to set a plug-and-play offer to a potential entrant whose capacity requirement is randomly distributed while satisficing their own requirements. Capacity cost exhibits sub-additive property so that there is room for profitable overcapacity setting in the first period. The entrant’s willingness-to-pay for the access to the infrastructure is dependent upon its standalone cost and the capacity gap that it must complete in case the available capacity is insufficient ex-post (the complement cost). Since initial capacity choices are driven by ex-ante (expected) yield extractible from the entrant we derive the expected complement cost function which helps us defining the investors’ objective function. We first show that this curve is decreasing and convex in the capacity increments and that it is shaped by the distribution function of the potential entrant’s requirements. We then derive the general form of solutions and solve the model for uniform and triangular distributions. Depending on requirements volumes and cost assumptions different equilibria occurs. We finally analyze the effect of a per-unit subsidy a public actor would apply to foster such sharing synergies.

Keywords: capacity, cooperation, industrial symbiosis, pricing

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Authors: S. Jonsson, D. Millard, C. Bokhove

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Smartphones are ubiquitous and frequently used as learning tools, which makes the design of educational apps an important area of research. A key issue is designing apps to encourage engagement while maintaining a focus on the educational aspects of the app. Flow experience is a promising method for addressing this issue, which refers to a mental state of cognitive absorption and positive emotion. Flow experience has been shown to be associated with positive emotion and increased learning performance. Studies have shown that immediate feedback is an antecedent to Flow. This experiment investigates the effect of immediate feedback on Flow experience. An app teaching Spanish phrases was developed, and 30 participants completed both a 10min session with immediate feedback and a 10min session with delayed feedback. The app contained a task where the user assembles Spanish phrases by pressing bricks with Spanish words. Immediate feedback was implemented by incorrect bricks recoiling, while correct brick moved to form part of the finished phrase. In the delayed feedback condition, the user did not know if the bricks they pressed were correct until the phrase was complete. The level of Flow experienced by the participants was measured after each session using the Flow Short Scale. The results showed that higher levels of Flow were experienced in the immediate feedback session. It was also found that 14 of the participants indicated that the demands of the task were ‘just right’ in the immediate feedback session, while only one did in the delayed feedback session. These results have implications for how to design educational technology and opens up questions for how Flow experience can be used to increase performance and engagement.

Keywords: feedback timing, flow experience, L2 language learning, mobile learning

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Authors: Eid Abo Hamza, Ahmed Helal

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Purpose: The objective is to measure the capacity of the working memory, ie. the maximum number of elements that can be retrieved and processed, by measuring the basic functions of working memory (inhibition/transfer/update), and also to investigate its relationship to life stress and depressive thoughts. Methods: The study sample consisted of 50 students from Egypt. A cognitive task was designed to measure the working memory capacity based on the determinants found in previous research, which showed that cognitive tasks are the best measurements of the functions and capacity of working memory. Results: The results indicated that there were statistically significant differences in the level of life stress events (high/low) on the task of measuring the working memory capacity. The results also showed that there were no statistically significant differences between males and females or between academic major on the task of measuring the working memory capacity. Furthermore, the results reported that there was no statistically significant effect of the interaction of the level of life stress (high/low) and gender (male/female) on the task of measuring working memory capacity. Finally, the results showed that there were significant differences in the level of depressive thoughts (high/low) on the task of measuring working memory. Conclusions: The current research concludes that neither the interaction of stressful life events, gender, and academic major, nor the interaction of depressive thoughts, gender, and academic major, influence on working memory capacity.

Keywords: working memory, depression, stress, life event

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Authors: J. Karthik, G. Vinayagamurthy

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Aerodynamic flow control is achieved by interaction of flowing medium with corresponding structure so that its natural flow state is disturbed to delay the transition point. This paper explains the aerodynamic effect and optimized design of Vortex Generators on the turbine blade to achieve maximum flow control. The airfoil is chosen from NREL [National Renewable Energy Laboratory] S-series airfoil as they are characterized with good lift characteristics and lower noise. Vortex generators typically chosen are Ogival, Rectangular, Triangular and Tapered Fin shapes attached near leading edge. Vortex generators are typically distributed from the primary to tip of the blade section. The design wind speed is taken as 6m/s and the computational analysis is executed. The blade surface is simulated using k- ɛ SST model and results are compared with X-FOIL results. The computational results are validated using Wind Tunnel Testing of the blade corresponding to the design speed. The effect of Vortex generators on the flow characteristics is studied from the results of analysis. By comparing the computational and test results of all shapes of Vortex generators; the optimized design is achieved for effective flow control corresponding to the blade.

Keywords: flow control, vortex generators, design optimisation, CFD

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Authors: K. Bhojnadh, M. Fiddler, D. Cheshire

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An investigation into the Kutta effect on the trailing edge of a subsonic aerofoil was conducted which led to an analysis using Ansys Fluent to determine the effect of flow separation over a NACA 0012 aerofoil. This aerofoil was subjected to oscillations to create an unsteady flow over the aerofoil, therefore, creating turbulence, with unsteady aerodynamics playing a key role to determine the flow regimes when the aerofoil is subjected to different angles of attack along with varying Reynolds numbers. Many theories were evolved to determine the flow parameters of a 2-D aerofoil in these unsteady conditions because they behave unpredictably at the trailing edge when subjected to a different angle of attack. The shear area observed in the boundary layer at the trailing edge tends towards an unsteady turbulent flow even at small angles of attack, creating drag as the flow separates, reducing the aerodynamic performance of aerofoil. In this paper, research was conducted to determine the effect of Kutta circulation over the aerofoil and the effect of that circulation in reducing the effect of pressure and boundary layer distribution over the aerofoil. The effect of circulation is observed by using Ansys Fluent by using varying flow parameters and differential schemes to observe the flow behaviour on the aerofoil. Initially, steady flow analysis was conducted on the aerofoil to determine the effect of circulation, and it was noticed that the effect of circulation could only be properly observed when the aerofoil is subjected to oscillations. Therefore, that was modelled by using Ansys user-defined functions, which define the motion of the aerofoil by creating a dynamic mesh on the aerofoil. Initial results were observed, and further development of the dynamic mesh functions in Ansys is taking place. This research will determine the overall basic principles of unsteady flow aerodynamics applied to the investigation of Kutta related circulation, and gives an indication regarding the generation of vortices which is discussed further in this paper.

Keywords: circulation, flow seperation, turbulence modelling, vortices

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Authors: Basant K. Jha, M. L. Kaurangini

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An approximate analytical solution is presented for convective flow in a horizontal channel filled with porous material. The Brinkman-Forchheimer extension of Darcy equation is utilized to model the fluid flow while the energy equation is utilized to model temperature distribution in the channel. The solutions were obtained utilizing the newly suggested technique and compared with those obtained from an implicit finite-difference solution.

Keywords: approximate analytical, convective flow, porous material, Brinkman-Forchiemer

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Authors: A. R. Momeninezhad

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Erosion of Slurry Pumps in Related Industries, is one of the major costs in their production process. Many factories in extractive industries try to find ways to diminish this cost. In this paper, we consider the flow pattern modifications by geometric variations made of numerical simulation of flow inside pump casing, which is one of the most important parts analyzed for erosion. The mentioned pump is a cyclone centrifugal slurry pump, which is operating in Sarcheshmeh Copper Industries in Kerman-Iran, named and tagged as HM600 cyclone pump. Simulation shows many improvements in local wear information and situations for better and more qualified design of casing shape and impeller position, before and after geometric corrections. By theory of liquid-solid two-phase flow, the local wear defeats are analyzed and omitted.

Keywords: flow pattern, slurry pump, simulation, wear

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Authors: Ngoc Minh Quynh Pham, Quan V. Vuong, Michael C. Bowyer, Christopher J. Scarlett

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Tuckeroo (Cupaniopsis anacardioides) is an Australian native plant and is grown in the coastal regions in New South Wales, Queensland and Northern Australia. Its fruits have been eaten by birds; however there is no information on phytochemical and antioxidant capacity of these fruits. This study aimed to determine the phenolic compounds (TPC), flavonoids (TFC), proanthocyanidins (TPro) and antioxidant capacity in the whole or different parts of tuckeroo fruit including skin, flesh and seed. Whole and partly tuckeroo fruits were collected and immediately freeze dried to constant weight and then ground to small particle sizes (<1mm mesh). Samples were extracted in 50% methanol using an ultrasonic bath set at temperature 40 °C for 30 minutes. TPC, TFC, TPro and antioxidant capacity were measured by spectrophotometric analysis. The results showed that the whole fruits contained 106.23 mg GAE/g of TPC, 67.67 mg CAE/g of TFC and 56.74 mg CAE/g of TPro. These fruits also possessed high antioxidant capacity (DPPH: 263.78 mg TroE/g, ABTS: 346.98 mg TroE/g, CUPRAC: 370.12 mg TroE/g and FRAP: 176.30 mg TroE/g), revealing that these fruits are rich source of antioxidants. The results also showed that distribution of the antioxidants was varied in different parts of the fruits. Skin had the highest levels of TPC, TFC, and TPro as well as antioxidant properties, followed by the seed and flesh had the lowest levels of phenolic compounds and antioxidant capacity. Of note, levels of phenolic compounds and antioxidant capacity of the skin were significantly higher than those of the whole fruits. Therefore, the skin of tuckeroo fruits is recommended as a starting material for extraction and purification of phenolic compounds as potential antioxidants for further utilisation in the food and pharmaceutical industries.

Keywords: antioxidant capacity, Cupaniopsis anacardioides, phenolic compounds, tuckeroo fruit

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Authors: Norita Ahmad, Reza Barkhi, Xiaobo Xu

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We design an experimental study to learn about the cognitive implications of the use of avatars in a Virtual World (VW) (i.e., Second Life). The results support our proposed model, where a positive flow experience with VW influences the attitude towards VW, in turn influencing intention to use VW. Furthermore, VW flow experience can itself be impacted by perceived peer influence, familiarity with VW, and personality of the individuals behind the avatars in VW.

Keywords: avatar, flow experience, personality type, second life, virtual world

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Authors: Othman S. Alsheraida, Sherif El-Gamal

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Fiber Reinforced Polymers (FRP) is a composite material with exceptional properties that are capable of replacing conventional steel reinforcement in reinforced and pre-stressed concrete structures. However, the main obstacle for their wide use in the pre-stressed concrete application is the anchorage system. Due to the weakness of FRP in the transverse direction, the pre-stressing capacity of FRP bars is limited. This paper investigates the modification of the conventional wedge anchorage system to be used for stressing of FRP bars in pre-stressed applications. Epoxy adhesive material with glass FRP (GFRP) bars and conventional steel wedge were used in this paper. The GFRP bars are encased with epoxy at the anchor zone and the wedge system was used in the pull-out test. The results showed a loading capacity of 47.6 kN which is 69% of the bar ultimate capacity. Additionally, nylon wedge was made with the same dimensions of the steel wedge and tested for GFRP bars without epoxy layer. The nylon wedge showed a loading capacity of 19.7 kN which is only 28.5% of the ultimate bar capacity.

Keywords: anchorage, concrete, epoxy, frp, pre-stressed

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Authors: A. V. Seryakov

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The work presents part calculation and part experimental research of the intensification of heat-transfer characteristics of medium-temperature heat pipes. Presented is a vapour jet nozzle, similar to the Laval nozzle, surrounded by a capillary-porous insert along the full length of the heat pipe axial to the direction of heat flow. This increases velocity of the vapour flow, heat-transfer coefficient and pulse rate of two-phase vapour flow.

Keywords: medium-temperature range heat pipes, capillary-porous insert, capillary steam injectors, Laval nozzle, condensation sensor

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Authors: Anshul Ashu

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Computers are applied to the vehicle aerodynamics in two ways. One of two is Computational Fluid Dynamics (CFD) and other is Computer Aided Flow Visualization (CAFV). Out of two CFD is chosen because it shows the result with computer graphics. The simulation of flow field around the vehicle is one of the important CFD applications. The flow field can be solved numerically using panel methods, k-ε method, and direct simulation methods. The spoiler is the tool in vehicle aerodynamics used to minimize unfavorable aerodynamic effects around the vehicle and the parallel spoiler is set of two spoilers which are designed in such a manner that it could effectively reduce the drag. In this study, the standard k-ε model of the simplified version of Bugatti Veyron, Audi R8 and Porsche 911 are used to simulate the external flow field. Flow simulation is done for variable Reynolds number. The flow simulation consists of three different levels, first over the model without a rear spoiler, second for over model with single rear spoiler, and third over the model with parallel rear-spoiler. The second and third level has following parameter: the shape of the spoiler, the angle of attack and attachment position. A thorough analysis of simulations results has been found. And a new parallel spoiler is designed. It shows a little improvement in vehicle aerodynamics with a decrease in vehicle aerodynamic drag and lift. Hence, it leads to good fuel economy and traction force of the model.

Keywords: drag, lift, flow simulation, spoiler

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Authors: M. C. Lin, C. W. Su

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The paper investigates the optimization analysis to the heat exchanger design, mainly with response surface method and genetic algorithm to explore the relationship between optimal fluid flow velocity and temperature of the heat exchanger using field synergy principle. First, finite volume method is proposed to calculate the flow temperature and flow rate distribution for numerical analysis. We identify the most suitable simulation equations by response surface methodology. Furthermore, a genetic algorithm approach is applied to optimize the relationship between fluid flow velocity and flow temperature of the heat exchanger. The results show that the field synergy angle plays vital role in the performance of a true heat exchanger.

Keywords: optimization analysis, field synergy, heat exchanger, genetic algorithm

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Authors: Kenji Gwee

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The Mental Capacity Act is a new legislation that allows for lasting powers of attorney and court-appointed deputies, in respect of people who lack legal capacity. While the UK Act, after which the Singapore Act is modeled, has been shown to be therapeutic to donors, the Singapore Act differs from its UK counterpart and it is unclear if the Singapore Act can be beneficial to donors as purported. The purpose of this study was to determine what the perceptions of three groups of stakeholders (patients, caregivers and psychiatrists) are about the aspects of the Mental Capacity Act that are therapeutic to donors. In addition, ways to increase the therapeutic value of the Act to donors are sought. A qualitative methodology was used and the research was guided by two theoretical frameworks: therapeutic jurisprudence and an interpretive constructive framework. Interviews with 12 psychiatrists, and focus groups with twenty three patients and seven caregivers showed agreement that, allowing donors to nominate more than one decision- maker, and whistle-blowing mechanisms for recourse for abuse, were therapeutic to donors. To further increase the therapeutic value of the Act, 2 suggestions were made: the Act should provide for (i) advanced healthcare directives- allowing donors to make advance decisions to refuse treatment, or cease existing treatment, and (ii) independent advocacy services- to have a case worker to represent people who have no family or friends and are thus unable to find suitable donees.

Keywords: Mental Capacity Act, therapeutic jurisprudence, qualitative methodology, the UK Act

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Authors: Abhishek Kumar Chandra, Kaushal Kishor, Wasim Khan, Dhananjay Singh, M. S. Alam

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Single phase fluid flow through series of uniform microchannels connected via transition section (converging-diverging section with or without throat) was analytically and numerically studied to characterize the flow within the channel and in the transition sections. Three sets of microchannels of diameters 100, 184, and 249 μm were considered for investigation. Each set contains 10 numbers of microchannels of length 20 mm, connected to each other in series via transition sections. Transition section consists of either converging-diverging section with throat or without throat. The effect of non-uniformity in microchannels on pressure drop was determined by passing water/air through the set of channels for Reynolds number 50 to 1000. Compressibility and rarefaction effects in transition sections were also tested analytically and numerically for air flow. The analytical and numerical results show that these configurations can be used in enhancement of transport processes. However, converging-diverging section without throat shows superior performance over with throat configuration.

Keywords: contraction-expansion flow, integrated microchannel, microchannel network, single phase flow

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Authors: Daniyar Bossinov

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This paper considers a non-isothermal stationary waxy crude oil flow in a two-dimensional axisymmetric pipe with the transition of a Newtonian fluid to a non-Newtonian fluid. The viscosity and yield stress of waxy crude oil are highly dependent on temperature changes. During the hot pumping of waxy crude oil through a buried pipeline, a non-isothermal flow occurs due to heat transfer to the surrounding soil. This leads to a decrease in flow temperature, an increase in viscosity, the appearance of yield stress, the crystallization of wax, and the deposition of solid particles on the pipeline's inner wall. The deposition of oil solid particles reduces a pipeline flow area and leads to the appearance of a stagnant zone with thermal insulation in the near-wall area. Waxy crude oil properties change. A Newtonian fluid at low temperatures transits to a non-Newtonian fluid. The one-dimensional modeling of a non-isothermal waxy crude oil flow in a two-dimensional axisymmetric pipeline by traditional averaging of temperature and velocity over the pipeline cross-section does not allow for explaining a physics phenomenon. Therefore, in this work, a two-dimensional flow model and the heat transfer of waxy oil are constructed. The calculated data show the transition of a Newtonian fluid to a non-Newtonian fluid due to the heat exchange of waxy oil with the environment.

Keywords: non-isothermal laminar flow, waxy crude oil, stagnant zone, yield stress

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Authors: Ainur Mukhambetova, Miras Karzhauov, Vyacheslav Ogay

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Introduction: Mesenchymal stem cells (MSCs) have the capacity to be differentiated into several cell lineages and are a promising source for cell therapy and tissue engineering. However, currently most MSCs culturing protocols use media supplemented with fetal bovine serum (FBS), which limits their application in clinic due to the possibility of zoonotic infections, contamination and immunological reactions. Consequently, formulating effective serum free culture medium becomes one of the important problems in contemporary cell biotechnology. Objectives: The aim of this study was to define an optimal serum-free medium for culturing of periosteum derived MSCs. Materials and methods: The MSCs were extracted from human periosteum and transferred to the culture flasks pretreated with CELLstart™. Immunophenotypic characterization, proliferation and in vitro differentiation of cells grown on STEM PRO® MSC SFM were compared to the cells cultured in the standard FBS containing media. Chromosome analysis and flow cytometry were also performed. Results: We have shown that cells were grown on STEM PRO® MSC SFM retained all the morphological, immunophenotypic (CD73, CD90, CD105, vimentin and Stro-1) and cell differentiation characteristics specific to MSCs. Chromosome analysis indicated no anomalies in the chromosome structure. Flow cytometry showed a high expression of cell adhesion molecules CD44 (98,8%), CD90 (97,4%), CD105 (99,1%). In addition, we have shown that cell is grown on STEM PRO® MSC SFM have higher proliferation capacity compared to cell expanded on standard FBS containing the medium. Conclusion: We have shown that STEM PRO® MSC SFM is optimal for culturing periosteum derived human MSCs which subsequently can be safely used in cell therapy.

Keywords: cell technologies, periosteum-derived MSCs, regenerative medicine, serum-free medium

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Authors: Haoui Rabah

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The aim of this work is to analyze a viscous flow around the axisymmetric blunt body taken into account the mesh size both in the free stream and into the boundary layer. The resolution of the Navier-Stokes equations is realized by using the finite volume method to determine the flow parameters and detached shock position. The numerical technique uses the Flux Vector Splitting method of Van Leer. Here, adequate time stepping parameter, CFL coefficient and mesh size level are selected to ensure numerical convergence. The effect of the mesh size is significant on the shear stress and velocity profile. The best solution is obtained with using a very fine grid. This study enabled us to confirm that the determination of boundary layer thickness can be obtained only if the size of the mesh is lower than a certain value limits given by our calculations.

Keywords: supersonic flow, viscous flow, finite volume, blunt body

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Authors: Nurul A. Hamzah, Tony Morris, Dan Van Der Westhuizen

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Music listening can potentially promote the achievement of flow state during exercise. Selecting music for exercise should consider the motivational factors-internal factors (music tempo and musicality) and external factors (cultural impact and association). This study was a cross-over study which was designed to examine the motivational qualities of music (participant-selected music and researcher-selected music) and flow state responses during exercise accompanying with music. 17 healthy participants (M=30.2, SD=6.3 years old) were among low physical activity individuals. Participants completed two separate sessions of 30 minutes of moderate intensity exercise (40-60% of Heart Rate Reserve) while listening to music. Half the participants at random were assigned to exercise with participant-selected music first, and half were assigned to exercise with researcher-selected music first. Parameters including flow state responses (Flow State Scale-2) and motivational music rating (Brunel Music Rating Inventory-2) were administered immediately after the exercise. Results from this study showed that there were no significant differences for both flow state t(32)=0.00, p>0.05 and motivational music rating t(32)= .393, p>0.05 between exercise with participant-selected music and exercise with researcher-selected music. Listening to music either participant or researcher selected music could promote flow experience during exercise when music is perceived as motivational. Music tempo and music preference are factors that could influence individuals to enjoy exercise and improve the exercise performance.

Keywords: motivational music, flow state, researcher-selected music, participant-selected music

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Authors: Shidvash Vakilipour, Scott Ormiston, Masoud Mohammadi, Rouzbeh Riazi, Kimia Amiri, Sahar Barati

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Two-phase and multi-phase flows are common flow types in fluid mechanics engineering. Among the basic and applied problems of these flow types, two-phase parallel flow is the one that two immiscible fluids flow in the vicinity of each other. In this type of flow, fluid properties (e.g. density, viscosity, and temperature) are different at the two sides of the interface of the two fluids. The most challenging part of the numerical simulation of two-phase flow is to determine the location of interface accurately. In the present work, a coupled interface tracking algorithm is developed based on Arbitrary Lagrangian-Eulerian (ALE) approach using a cell-centered, pressure-based, coupled solver. To validate this algorithm, an analytical solution for fully developed two-phase flow in presence of gravity is derived, and then, the results of the numerical simulation of this flow are compared with analytical solution at various flow conditions. The results of the simulations show good accuracy of the algorithm despite using a nearly coarse and uniform grid. Temporal variations of interface profile toward the steady-state solution show that a greater difference between fluids properties (especially dynamic viscosity) will result in larger traveling waves. Gravity effect studies also show that favorable gravity will result in a reduction of heavier fluid thickness and adverse gravity leads to increasing it with respect to the zero gravity condition. However, the magnitude of variation in favorable gravity is much more than adverse gravity.

Keywords: coupled solver, gravitational force, interface tracking, Reynolds number to Froude number, two-phase flow

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Authors: Hyeongbok Kim, Lingling Zhao, Xiaohong Su, Junjie Wang

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The Bernoulli filter is a precise Bayesian filter for single target tracking based on the random finite set theory. The standard Bernoulli filter often underestimates the number of targets. This study proposes a Gaussian particle flow (GPF) Bernoulli filter employing particle flow to migrate particles from prior to posterior positions to improve the performance of the standard Bernoulli filter. By employing the particle flow filter, the computational speed of the Bernoulli filters is significantly improved. In addition, the GPF Bernoulli filter provides a more accurate estimation compared with that of the standard Bernoulli filter. Simulation results confirm the improved tracking performance and computational speed in two- and three-dimensional scenarios compared with other algorithms.

Keywords: Bernoulli filter, particle filter, particle flow filter, random finite sets, target tracking

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Authors: W. Rashmi, M. Khalid, O. Seiksan, R. Saidur, A. F. Ismail

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Nanofluids have received much more attention since its discovery. They are believed to be promising coolants in heat transfer applications due to their enhanced thermal conductivity and heat transfer characteristics. In this study, the enhancement in heat transfer of CNT-nanofluids under turbulent flow conditions is investigated experimentally. Carbon nanotube (CNTs) concentration was varied between 0.051-0.085 wt%. The nanofluid suspension was stabilized by gum arabic (GA) through a process of homogenisation and sonication. The flow rates of cold fluid (water) is varied from 1.7-3 L/min and flow rates of the hot fluid is varied between 2-3.5 L/min. Thermal conductivity, density and viscosity of the nanofluids were also measured as a function of temperature and CNT concentration. The experimental results are validated with theoretical correlations for turbulent flow available in the literature. Results showed an enhancement in heat transfer range between 9-67% as a function of temperature and CNT concentration.

Keywords: nanofluids, carbon nanotubes (CNT), heat transfer enhancement, heat transfer

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Authors: Spandan Sahu, Amiya Kumar Pati, Kishanjit Kumar Khatua

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River is our main source of water which is a form of open channel flow and the flow in open channel provides with many complex phenomenon of sciences that needs to be tackled such as the critical flow conditions, boundary shear stress and depth averaged velocity. During floods, part of a river is carried by the simple main channel and rest is carried by flood plains. For such compound asymmetric channels, the flow structure becomes complicated due to momentum exchange between main channel and adjoining flood plains. Distribution of boundary shear in subsections provides us with the concept of momentum transfer between the interface of main channel and the flood plains. Experimentally, to get better data with accurate results are very complex because of the complexity of the problem. Hence, CES software has been used to tackle the complex processes to determine the shear stresses at different sections of an open channel having asymmetric flood plains on both sides of the main channel and the results is compared with the symmetric flood plains for various geometrical shapes and flow conditions. Error analysis is also performed to know the degree of accuracy of the model implemented.

Keywords: depth average velocity, non prismatic compound channel, relative flow depth, velocity distribution

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Authors: E. K. Soyele

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This study is on capacity building and motivation as determinants of productivity among library personnel in colleges of education in South West, Nigeria. This study made use of a descriptive research design of survey type. A total enumeration sampling technique was used for the selected sample. The research sample consisted of 40 library personnel. The instrument used for the study was a structured questionnaire divided into four parts. Statistics data analysis used were descriptive statistics with frequencies, percentages, and regression statistics analysis. Findings from this study revealed that capacity building and motivation have positive impact on library personnel productivity with their percentages greater than 50% acceptance level. A test of null hypotheses at P < 0.05 significant level was tested to see the significance between capacity building and productivity, which was positive at P < 0.05 significant level. This implies that capacity building and motivation significantly determine productivity among library personnel in selected college libraries in Nigeria. The study concluded that there is need for institutions to equip their library personnel via training programmes, in-service, digital training, ICT training, seminars, and conferences, etc. Incentives should be provided to motivate personnel for high productivity. The study, therefore, recommends that government, institutions and library management should fund college libraries adequately so as to enhance capacity building, staff commitment and training for further education

Keywords: capacity building, library personnel, motivation, productivity

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Authors: Sabrina Nouri, Abderahmane Ghezal, Said Abboudi, Pierre Spiteri

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This paper deals with the numerical study of heat and mass transfer of laminar flow transition at low Prandtl numbers. The model includes the two-directional momentum, the energy and mass transfer equations. These equations are discretized by the finite volume method and solved by a self-made simpler like Fortran code. The effect of governing parameters, namely the Lewis and Prandtl numbers, on the transition of the flow and solute distribution is studied for positive and negative thermal and solutal buoyancy forces ratio. Nusselt and Sherwood numbers are derived for of Prandtl [10⁻²-10¹] and Lewis numbers [1-10⁴]. The results show unicell and multi-cell flow. Solute and flow boundary layers appear for low Prandtl number.

Keywords: natural convection, low Prandtl number, heat and mass transfer, finite volume method

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Authors: Yutae Lee

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This paper considers a discrete-time bulk-arrival bulkservice queueing system, where service capacity varies depending on the previous service time. By using the generating function technique and the supplementary variable method, we compute the distributions of the queue length at an arbitrary slot boundary and a departure time.

Keywords: discrete-time queue, bulk queue, variable service capacity, queue length distribution

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Authors: M. Bouinoun, M. Bouhadef

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The present study is concerned with the problem of determining the shape of the free surface flow in a hydraulic channel which has an uneven bottom. For the mathematical formulation of the problem, the fluid of the two-dimensional irrotational steady flow in water is assumed inviscid and incompressible. The solutions of the nonlinear problem are obtained by using the usual conformal mapping theory and Hilbert’s technique. An experimental study, for comparing the obtained results, has been conducted in a hydraulic channel (subcritical regime and supercritical regime).

Keywords: free-surface flow, experiments, numerical method, uneven bottom, supercritical regime, subcritical regime

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Authors: Muhammad Umar Kiani, Muhammad Shahbaz, Hassan Akbar

Abstract:

Simulation of a high speed inviscid steady ideal air flow around a 2D/axial-symmetry body was carried out by the use of mb_cns code. mb_cns is a program for the time-integration of the Navier-Stokes equations for two-dimensional compressible flows on a multiple-block structured mesh. The flow geometry may be either planar or axisymmetric and multiply-connected domains can be modeled by patching together several blocks. The main simulation code is accompanied by a set of pre and post-processing programs. The pre-processing programs scriptit and mb_prep start with a short script describing the geometry, initial flow state and boundary conditions and produce a discretized version of the initial flow state. The main flow simulation program (or solver as it is sometimes called) is mb_cns. It takes the files prepared by scriptit and mb_prep, integrates the discrete form of the gas flow equations in time and writes the evolved flow data to a set of output files. This output data may consist of the flow state (over the whole domain) at a number of instants in time. After integration in time, the post-processing programs mb_post and mb_cont can be used to reformat the flow state data and produce GIF or postscript plots of flow quantities such as pressure, temperature and Mach number. The current problem is an example of supersonic inviscid flow. The flow domain for the current problem (strake configuration wing) is discretized by a structured grid and a finite-volume approach is used to discretize the conservation equations. The flow field is recorded as cell-average values at cell centers and explicit time stepping is used to update conserved quantities. MUSCL-type interpolation and one of three flux calculation methods (Riemann solver, AUSMDV flux splitting and the Equilibrium Flux Method, EFM) are used to calculate inviscid fluxes across cell faces.

Keywords: steady flow simulation, processing programs, simulation code, inviscid flux

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