Search results for: lateral flow assay

Authors: K. N. Kiran, S. Anish

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It is well known that secondary flow loses account about one third of the total loss in any axial turbine. Modern gas turbine height is smaller and have longer chord length, which might lead to increase in secondary flow. In order to improve the efficiency of the turbine, it is important to understand the behavior of secondary flow and device mechanisms to curtail these losses. The objective of the present work is to understand the effect of a stream wise end-wall fence on the aerodynamics of a linear turbine cascade. The study is carried out computationally by using commercial software ANSYS CFX. The effect of end-wall on the flow field are calculated based on RANS simulation by using SST transition turbulence model. Durham cascade which is similar to high-pressure axial flow turbine for simulation is used. The aim of fencing in blade passage is to get the maximum benefit from flow deviation and destroying the passage vortex in terms of loss reduction. It is observed that, for the present analysis, fence in the blade passage helps reducing the strength of horseshoe vortex and is capable of restraining the flow along the blade passage. Fence in the blade passage helps in reducing the under turning by 7⁰ in comparison with base case. Fence on end-wall is effective in preventing the movement of pressure side leg of horseshoe vortex and helps in breaking the passage vortex. Computations are carried for different fence height whose curvature is different from the blade camber. The optimum fence geometry and location reduces the loss coefficient by 15.6% in comparison with base case.

Keywords: boundary layer fence, horseshoe vortex, linear cascade, passage vortex, secondary flow

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Authors: Yonghwa Lee, Yoon Suk Kim, Yongsub Yi

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This study was to confirm the effects of anti-melanogenesis and anti-inflammatory effects from Opuntia humifusa fruit and stem extracts. A potent anti-oxidant activity was shown from the leaf extract at IC50 value of 38.33±1.07 μg/mL and fruit extract at IC50 value of 40.23±2.21 μg/mL by 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. Also, phenolic contents were confirmed total phenolic assay by high performance liquid chromatography (HPLC). Fraction of taxifolin from leaf extract was identified using HPLC and gas chromatography/mass spectrometry. The extracts of Opuntia humifusa fruit and stem were confirmed about toxicity effect in B16 F1 by cell viability. Melanin contents were decreased. Opuntia humifusa fruit and stem extracts had a positive effect of melanin synthesis inhibition for skin whitening. In investigating the anti-inflammatory activities of Opuntia humifusa, the results of cell viability indicated that taxifolin did not show cytotoxicity on RAW264.7 cells at 500 μM of concentration. The results show that taxifolin inhibited lipopolysaccharide (LPS)-induced production of Nitrite oxide (NO). In addition, taxifolin indicated the inhibition of lipopolysaccharide (LPS)-induced tumor necrosis factor (TNF) -α and interleukin (IL) -6 productions by cytokine assay and cyclooxygenase (COX)-2 expression by western blot analysis, meaning that taxifolin had a significant anti-inflammatory effect. Our results suggested that taxifolin from Opuntia humifusa has anti-melanogenesis and anti-inflammatory activities.

Keywords: anti-melanogenesis, anti-inflammatory, Opuntia humifusa, taxifolin

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Authors: G. K. Guseynova, V. V. Krylov, L. T. Khamidova, N. A. Polunina, V. A. Lukyanchikov

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The report presents complex ultrasound diagnostics in patients with symptomatic steno-occlusive lesions of extra- and intracranial branches of brachiocephalic arteries (BCA). The tasks and possibilities of ultrasound diagnostics at different stages of treatment of patients with symptomatic occlusion of internal carotid artery (ICA) are covered in detail; qualitative and quantitative characteristics of blood flow; parameters of the wall and lumen of the main arteries of the head; methods of ultrasound examination of indirect assessment of the functional status are presented. Special attention is paid to the description of indicators that are predictors of the consistency of formed extra-intracranial low-flow shunts, examples of functioning and failed anastomoses are analyzed.

Keywords: CBF, cerebral blood flow; CTA, external carotid artery; ICA, internal carotid artery; MCA, middle cerebral artery; MRA, magnetic resonance angiography; OEF, oxygen extraction fraction; TIA, transient ischaemic attack, ultrasound, low-flow bypass, anastomoses

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Authors: Yu-Kai Ting, Jia-Ying Tu, Chung-Chun Hsiao

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New physical insights into the nonlinear Lorenz equations related to flow resistance is discussed in this work. The chaotic dynamics related to Lorenz equations has been studied in many papers, which is due to the sensitivity of Lorenz equations to initial conditions and parameter uncertainties. However, the physical implication arising from Lorenz equations about convectional motion attracts little attention in the relevant literature. Therefore, as a first step to understand the related fluid mechanics of convectional motion, this paper derives the Lorenz equations again with different forced conditions in the model. Simulation work of the modified Lorenz equations without the viscosity or buoyancy force is discussed. The time-domain simulation results may imply that the states of the Lorenz equations are related to certain flow speed and flow resistance. The flow speed of the underlying fluid system increases as the flow resistance reduces. This observation would be helpful to analyze the coupling effects of different fluid parameters in a convectional model in future work.

Keywords: Galerkin method, Lorenz equations, Navier-Stokes equations, convectional motion

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Authors: Jin-Hong Kim

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Hydraulic analysis on microhabitat of Benthic Macro- invertebrates was performed at riparian riffles of Hongcheon River and Gapyeong Stream. As for the representative species, Ecdyonurus kibunensis, Paraleptophlebia cocorata, Chironomidae sp. and Psilotreta kisoensis iwata were chosen. They showed hydraulically different habitat types by flow velocity and particle diameters of streambed materials. Habitat conditions of the swimmers were determined mainly by the flow velocity rather than by flow depth or by riverbed materials. Burrowers prefer sand and silt, and inhabited at the riverbed. Sprawlers prefer cobble or boulder and inhabited for velocity of 0.05-0.15 m/s. Clingers prefer pebble or cobble and inhabited for velocity of 0.06-0.15 m/s. They were found to be determined mainly by the flow velocity.

Keywords: benthic macroinvertebrates, riffles, clinger, swimmer, burrower, sprawler

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Authors: Christoph Speer

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Decentralized ventilation systems should combine a small and economical design with high aerodynamic and thermal efficiency. The Counter Flow Heat Recovery Fan (CHRF) provides the ability to meet these requirements by using only one cross flow fan with a large number of blades to generate both airflows and which simultaneously acts as a regenerative counter flow heat exchanger. The successful development of the first laboratory prototype has shown the potential of this ventilation system. Occurring condensate on the surfaces of the fan blades during the cold and dry season can be recovered through the characteristic mode of operation. Hence the CHRF provides the possibility to avoid the need for frost protection and condensate drain. Through the implementation of system-specific solutions for flow balancing and summer bypass the required functionality is assured. The scalability of the CHRF concept allows the use in renovation as well as in new buildings from single-room devices through to systems for office buildings. High aerodynamic and thermal efficiency and the lower number of required mechatronic components should enable a reduction in investment as well as operating costs. The rotor is the key component of the system, the requirements and possible implementation variants are presented.

Keywords: CHRF, counter flow heat recovery fan, decentralized ventilation system, renovation

Procedia PDF Downloads 331

Authors: Anas El Amraoui, Abdelkhalek Cheddadi, Mohammed Touhami Ouazzani

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Laminar natural convection in a cylindrical annular cavity filled with air and provided with two fins is studied numerically using the discretization of the governing equations with the Centered Finite Difference method based on the Alternating Direction Implicit (ADI) scheme. The fins are attached to the inner cylinder of radius r_i (hot wall of temperature T_i). The outer cylinder of radius r_o is maintained at a temperature T_o (T_o < T_i). Two values of the dimensionless thickness of the fins are considered: 0.015 and 0.203. We consider a low fin height equal to 0.078 and medium fin heights equal to 0.093 and 0.203. The position of the fin is 0.82π and the radius ratio is equal to 2. The effect of Rayleigh number, Ra, on the flow structure and heat transfer is analyzed for a range of Ra from 10³ to 10⁴. The results for established flow structures and heat transfer at low height indicate that the flow regime that occurs is unicellular for all Ra and fin thickness; in addition, the heat transfer rate increases with increasing Rayleigh number and is the same for both thicknesses. At median fin heights 0.093 and 0.203, the increase of Rayleigh number leads to transitions of flow structure which correspond to significant variations of the heat transfer. The critical Rayleigh numbers, Ra_c.app and Ra_c.disp corresponding to the appearance of the bicellular flow regime and its disappearance, are determined and their influence on the change of heat transfer rate is analyzed.

Keywords: natural convection, fins, critical Rayleigh number, heat transfer, fluid flow regime, horizontal annulus

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Authors: Annamária Käferné Rácz, Bence Jáger, Balázs Kövesdi, László Dunai

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Due to the numerous advantages of steel corrugated web girders, its application field is growing for bridges as well as for buildings. The global stability behavior of such girders is significantly larger than those of conventional I-girders with flat web, thus the application of the structural steel material can be significantly reduced. Design codes and specifications do not provide clear and complete rules or recommendations for the determination of the lateral torsional buckling (LTB) resistance of corrugated web girders. Therefore, the authors made a thorough investigation regarding the LTB resistance of the corrugated web girders. Finite element (FE) simulations have been performed to develop new design formulas for the determination of the LTB resistance of trapezoidally corrugated web girders. FE model is developed considering geometrical and material nonlinear analysis using equivalent geometric imperfections (GMNI analysis). The equivalent geometric imperfections involve the initial geometric imperfections and residual stresses coming from rolling, welding and flame cutting. Imperfection sensitivity analysis was performed to determine the necessary magnitudes regarding only the first eigenmodes shape imperfections. By the help of the validated FE model, an extended parametric study is carried out to investigate the LTB resistance for different trapezoidal corrugation profiles. First, the critical moment of a specific girder was calculated by FE model. The critical moments from the FE calculations are compared to the previous analytical calculation proposals. Then, nonlinear analysis was carried out to determine the ultimate resistance. Due to the numerical investigations, new proposals are developed for the determination of the LTB resistance of trapezoidally corrugated web girders through a modification factor on the design method related to the conventional flat web girders.

Keywords: corrugated web, lateral torsional buckling, critical moment, FE modeling

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Authors: Malkhan Thakur, P. Deepak Kumar, P. K. S. Dikshit

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In recent years, the hydraulic behavior of side weirs has been the subject of many investigations. Most of the studies have been in connection with specific problems and have involved models. This is perhaps understandable, since a generalized treatment is made difficult by the large number of possible variables to be used to define the problem. A variety of empirical head discharge relationships have been suggested for side weirs. These empirical approaches failed to adequately consider the actual situation, and produced equations applicable only in circumstances virtually identical to those of the experiment. The present investigation is targeted to study to a greater depth the effect of different trapezium angles of a trapezoidal side weir and study of water surface profile in spatially varied flow with decreasing discharge maintaining the main channel flow subcritical. On the basis of experiment, the relationship between upstream Froude number and coefficient of discharge has been established. All the characteristics of spatially varied flow with decreasing discharge have been studied and subsequently formulated. The scope of the present investigation has been basically limited to a one-dimensional model of flow for the purpose of analysis. A formulation has been derived using the theoretical concept of constant specific energy. Coefficient of discharge has been calculated and experimental results were presented.

Keywords: weirs, subcritical flow, rectangular channel, trapezoidal side weir

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Authors: Patrícia Pires, Renata Vaz, Bárbara Teles, Marco Pato, Pedro Beckert

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Introduction: The management of lateral third clavicle fractures can be challenging due to difficulty in distinguishing subtle variations in the fracture pattern, which may be suggestive of potential fracture instability. They occur most often in men between 30 and 50 years of age, and in individuals over 70 years of age, its distribution is equal between both men and women. These fractures account for 10%–30% of all clavicle fractures and roughly 30%–45% of all clavicle nonunion fractures. Lateral third clavicle fractures may be treated conservatively or surgically, and there is no gold standard, although the risk of nonunion or pseudoarthrosis impacts the recommendation of surgical treatment when these fractures are unstable. There are many strategies for surgical treatment, including locking plates, hook plates fixation, coracoclavicular fixation using suture anchors, devices or screws, tension band fixation with suture or wire, transacromial Kirschner wire fixation and arthroscopically assisted techniques. Whenever taking the hardware into consideration, we must not disregard that obtaining adequate lateral fixation of small fragments is a difficult task, and plates are more associated to local irritation. The aim of the appropriate treatment is to ensure fracture healing and a rapid return to preinjury activities of daily living but, as explained, definitive treatment strategies have not been established and the variety of techniques avalilable add up to the discussion of this topic. Methods and Results: We present a clinical case of a 43-year-old man with the diagnosis of a lateral third clavicle fracture (Neer IIC) in the sequence of a fall on his right shoulder after a bicycle fall. He was operated three days after the injury, and through K-wire temporary fixation and indirect reduction using a ZipTight, he underwent osteosynthesis with an interfragmentary figure-of-eight tension band with polydioxanone suture (PDS). Two weeks later, there was a good aligment. He kept the sling until 6 weeks pos-op, avoiding efforts. At 7-weeks pos-op, there was still a good aligment, starting the physiotherapy exercises. After 10 months, he had no limitation in mobility or pain and returned to work with complete recovery in strength. Conclusion: Some distal clavicle fractures may be conservatively treated, but it is widely accepted that unstable fractures require surgical treatment to obtain superior clinical outcomes. In the clinical case presented, the authors chose an osteosuture technique due to the fracture pattern, its location. Since there isn´t a consensus on the prefered fixation method, it is important for surgeons to be skilled in various techniques and decide with their patient which approach is most appropriate for them, weighting the risk-benefit of each method. For instance, with the suture technique used, there is no wire migration or breakage, and it doesn´t require a reoperation for hardware removal; there is also less tissue exposure since it requires a smaller approach in comparison to the plate fixation and avoids cuff tears like the hook plate. The good clinical outcome on this case report serves the purpose of expanding the consideration of this method has a therapeutic option.

Keywords: lateral third, clavicle, suture, fixation

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Authors: S. K. Khosrowshahi, E. Güler

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This study investigates the reinforcement function of geosynthetics on the shear strength and strain profile of sand. Conducting a series of simple shear tests, the shearing behavior of the samples under static and cyclic loads was evaluated. Three different types of geosynthetics including geotextile and geonets were used as the reinforcement materials. An image processing analysis based on the optical flow method was performed to measure the lateral displacements and estimate the shear strains. It is shown that besides improving the shear strength, the geosynthetic reinforcement leads a remarkable reduction on the shear strains. The improved layer reduces the required thickness of the soil layer to resist against shear stresses. Consequently, the geosynthetic reinforcement can be considered as a proper approach for the sustainable designs, especially in the projects with huge amount of geotechnical applications like subgrade of the pavements, roadways, and railways.

Keywords: image processing, soil reinforcement, geosynthetics, simple shear test, shear strain profile

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Authors: Faezeh Mohammadi, Ebrahim Ebrahimi, Neda Azimi

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Use of ultrasound waves is one of the techniques for increasing the mixing and mass transfer in the microdevices. Ultrasound propagation into liquid medium leads to stimulation of the fluid, creates turbulence and so increases the mixing performance. In this study, CFD modeling of two-phase flow in a pitted micromixer equipped with a piezoelectric with frequency of 1.7 MHz has been studied. CFD modeling of micromixer at different velocity of fluid flow in the absence of ultrasound waves and with ultrasound application has been performed. The hydrodynamic of fluid flow and mixing efficiency for using ultrasound has been compared with the layout of no ultrasound application. The result of CFD modeling shows well agreements with the experimental results. The results showed that the flow pattern inside the micromixer in the absence of ultrasound waves is parallel, while when ultrasound has been applied, it is not parallel. In fact, propagation of ultrasound energy into the fluid flow in the studied micromixer changed the hydrodynamic and the forms of the flow pattern and caused to mixing enhancement. In general, from the CFD modeling results, it can be concluded that the applying ultrasound energy into the liquid medium causes an increase in the turbulences and mixing and consequently, improves the mass transfer rate within the micromixer.

Keywords: CFD modeling, ultrasound, mixing, mass transfer

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Authors: Vikas Kumar

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The present study is carried out to investigate the magneto-viscous effects on incompressible ferrofluid flow over a porous rotating disc with suction or injection on the surface of the disc subjected to a magnetic field. The flow under consideration is axi-symmetric steady ferrofluid flow of electrically non-conducting fluid. Karman’s transformation is used to convert the governing boundary layer equations involved in the problem to a system of non linear coupled differential equations. The solution of this system is obtained by using power series approximation. The flow characteristics i.e. radial, tangential, axial velocities and boundary layer displacement thickness are calculated for various values of MFD (magnetic field dependent) viscosity and for different values of suction injection parameter. Besides this, skin friction coefficients are also calculated on the surface of the disk. Thus, the obtained results are presented numerically and graphically in the paper.

Keywords: axi-symmetric, ferrofluid, magnetic field, porous rotating disk

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Authors: Pavan K. Emani, Shashank Kothari, V. S. Phanikanth

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The ultimate load analysis of RC pile groups has assumed a lot of significance under liquefying soil conditions, especially due to post-earthquake studies of 1964 Niigata, 1995 Kobe and 2001 Bhuj earthquakes. The present study reports the results of numerical simulations on pile groups subjected to monotonically increasing lateral loads under design amounts of pile axial loading. The soil liquefaction has been considered through the non-linear p-y relationship of the soil springs, which can vary along the depth/length of the pile. This variation again is related to the liquefaction potential of the site and the magnitude of the seismic shaking. As the piles in the group can reach their extreme deflections and rotations during increased amounts of lateral loading, a precise modeling of the inelastic behavior of the pile cross-section is done, considering the complete stress-strain behavior of concrete, with and without confinement, and reinforcing steel, including the strain-hardening portion. The possibility of the inelastic buckling of the individual piles is considered in the overall collapse modes. The model is analysed using Riks analysis in finite element software to check the post buckling behavior and plastic collapse of piles. The results confirm the kinds of failure modes predicted by centrifuge test results reported by researchers on pile group, although the pile material used is significantly different from that of the simulation model. The extension of the present work promises an important contribution to the design codes for pile groups in liquefying soils.

Keywords: collapse load analysis, inelastic buckling, liquefaction, pile group

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Authors: Humanyun Zahir, Irtsam Ghazi

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This report outlines the basic installation and operation of magnetic inductive flow velocity sensors on large underground cooling water pipelines. Research on the effects of cathodic protection as well as into other factors that might influence the overall performance of the meter are presented in this paper. The experiments were carried out on an immersion type magnetic meter specially used for flow measurement of cooling water pipeline. An attempt has been made in this paper to outline guidelines that can ensure accurate measurement related to immersion type magnetic meters on underground pipelines.

Keywords: magnetic induction, flow meter, Faraday's law, immersion, cathodic protection, anode, cathode, flange, grounding, plant information management system, electrodes

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Authors: Naila Safdar, Faria Riasat, Azra Yasmin

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Lychee is an emerging fruit crop in Pakistan. Two famous cultivars of lychee, Gola and Surakhi, were collected from Khanpur Orchard, Pakistan and their whole fruit (including peel, pulp and seed) was investigated for pomological features and therapeutic activities. Both cultivars differ in shape and size with Gola having large size (3.27cm length, 2.36cm width) and more flesh to seed ratio (8.65g). FTIR spectroscopy and phytochemical tests confirmed presence of different bioactive compounds like phenol, flavonoids, quinones, anthraquinones, tannins, glycosides, and alkaloids, in both lychee fruits. Atomic absorption spectroscopy indicated an increased amount of potassium, magnesium, sodium, iron, and calcium in Gola and Surakhi fruits. Small amount of trace metals, zinc and copper, were also detected in lychee fruit, while heavy metals lead, mercury, and nickel were absent. These two lychee cultivars were also screened for antitumor activity by Potato disc assay with maximum antitumor activity shown by aqueous extract of Surakhi seed (77%) followed by aqueous extract of Gola pulp (74%). Antimicrobial activity of fruit parts was checked by agar well diffusion method against six bacterial strains Enterococcus faecium, Enterococcus faecalis, Staphylococcus aureus, Bacillus subtilis, Bacillus sp. MB083, and Bacillus sp. MB141. Highest antimicrobial activity was shown by methanolic extract of Gola pulp (27mm ± 0.70) and seed (19.5mm ± 0.712) against Enterococcus faecalis. DPPH scavenging assay revealed highest antioxidant activity by aqueous extract of Gola peel (98.10%) followed by n-hexane extract of Surakhi peel (97.73%). Results obtained by reducing power assay also corroborated with the results of DPPH scavenging activity.

Keywords: antimicrobial evaluation, antitumor assay, gola, phytoconstituents, reactive oxygen species, Surakhi

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Authors: Abhisek Sarkar, Abhimanyu Gaur

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In this report we have discussed the theoretical aspects of the flow transformation, occurring through a series of bifurcations. The parameters and their continuous diversion, the intermittent bursts in the transition zone, variation of velocity and pressure with time, effect of roughness in turbulent zone, and changes in friction factor and head loss coefficient as a function of Reynolds number for a transverse flow across a cylinder have been discussed. An analysis of the variation in the wake length with Reynolds number was done in FORTRAN.

Keywords: bifurcation, attractor, intermittence, energy cascade, energy spectra, vortex stretching

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Authors: Ergün Şakalar, Şeyma Özçirak Ergün

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Pistachio nuts, the fruits of the pistachio tree (Pistacia vera), are edible tree nuts highly valued for their organoleptic properties. Pistachio nuts used in snack foods, chocolates, baklava, meat products, ice-cream industries and other gourmet products as ingredients. Undeclared pistachios may be present in food products as a consequence of fraudulent substitution. Control of food samples is very important for safety and fraud. Mix of pistachio, peanut (Arachis hypogaea), pea (Pisum sativum L.) used instead of pistachio in food products, because pistachio is a considerably expensive nut. To solve this problem, a sensitive polymerase chain reaction PCR has been developed. A real-time PCR assay for the detection of pea, peanut and pistachio in baklava was designed by using EvaGreen fluorescence dye. Primers were selected from powerful regions for identification of pea, peanut and pistachio. DNA from reference samples and industrial products were successfully extracted with the GIDAGEN® Multi-Fast DNA Isolation Kit. Genomes were identified based on their specific melting peaks (Mp) which are 77°C, 85.5°C and 82.5°C for pea, peanut and pistachio, respectively. Homogenized mixtures of raw pistachio, pea and peanut were prepared with the ratio of 0.01%, 0.1%, 1%, 10%, 40% and 70% of pistachio. Quantitative detection limit of assay was 0.1% for pistachio. Also, real-time PCR technique used in this study allowed the qualitative detection of as little as 0.001% level of peanut DNA, 0,000001% level of pistachio DNA and 0.000001% level of pea DNA in the experimental admixtures. This assay represents a potentially valuable diagnostic method for detection of nut species adulterated with pistachio as well as for highly specific and relatively rapid detection of small amounts of pistachio in food samples.

Keywords: pea, peanut, pistachio, real-time PCR

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Authors: Ryan D. Hoult

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The inherent assumption in the elementary theory of bending that plane sections remain plane is commonly used in the design of reinforced concrete members. However, in reality, a shear flow would develop in non-rectangular sections, where the longitudinal strains in between the web and flanges of the element would lag behind those at the boundary ends. This phenomenon, known as shear lag, can significantly reduce the expected moment capacity of non-rectangular reinforced concrete walls. This study focuses on shear lag effects in reinforced concrete U-shaped walls, which are commonly used as lateral load resisting elements in reinforced concrete buildings. An extensive number of finite element modelling analyses are conducted to estimate the vertical strain distributions across the web and flanges of a U-shaped wall with different axial load ratios and longitudinal reinforcement detailing. The results show that shear lag effects are prominent and sometimes significant in U-shaped walls, particularly for the wall sections perpendicular to the direction of loading.

Keywords: shear lag, walls, U-shaped, moment-curvature

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Authors: Karthikeyan M., Paul M. J.

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This case report discusses a 54-year-old woman from Salem, Tamilnadu, who presented with a rare case of papillary thyroid carcinoma (PTC), manifesting as a hypervascular mass in the left carotid sheath. The patient had a two-and-a-half-month history of non-progressive neck swelling, with symptoms including dysphagia and a choking sensation. Clinical examination and investigations such as FNAC and CECT revealed a large vascular mass in the left neck region, initially perplexing the diagnosis. The patient underwent total thyroidectomy and excision of the left carotid sheath mass. Histopathology confirmed PTC. Postoperatively, the patient received Iodine-131 ablation and showed good recovery with no recurrence. This case highlights the diagnostic challenge and atypical presentation of PTC as a vascular neck mass, emphasizing the importance of a comprehensive approach in evaluating thyroid and neck lesions.

Keywords: lateral neck vascular mass, lateral aberrant thyroid, thyroid vascular swelling, smooth post op recovery

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Authors: Tomas Berhanu Bekele

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Traffic congestion is one of the main problems related to transportation in developed as well as developing countries. Traffic control systems are based on the idea of avoiding traffic instabilities and homogenizing traffic flow in such a way that the risk of accidents is minimized and traffic flow is maximized. Lately, Intelligent Transport Systems (ITS) has become an important area of research to solve such road traffic-related issues for making smart decisions. It links people, roads and vehicles together using communication technologies to increase safety and mobility. Moreover, accurate prediction of road traffic is important to manage traffic congestion. The aim of this study is to develop an ANN model for the prediction of traffic flow and to compare the ANN model with the linear regression model of traffic flow predictions. Data extraction was carried out in intervals of 15 minutes from the video player. Video of mixed traffic flow was taken and then counted during office work in order to determine the traffic volume. Vehicles were classified into six categories, namely Car, Motorcycle, Minibus, mid-bus, Bus, and Truck vehicles. The average time taken by each vehicle type to travel the trap length was measured by time displayed on a video screen.

Keywords: intelligent transport system (ITS), traffic flow prediction, artificial neural network (ANN), linear regression

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

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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 155

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

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The river is our main source of water which is a form of open channel flow and the flow in the open channel provides with many complex phenomena of sciences that need to be tackled such as the critical flow conditions, boundary shear stress, and depth-averaged velocity. The development of society, more or less solely depends upon the flow of rivers. The rivers are major sources of many sediments and specific ingredients which are much essential for human beings. 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 the main channel and adjoining flood plains. Distribution of boundary shear in subsections provides us with the concept of momentum transfer between the interface of the 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 are 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: M. H. Alhajeri, Hamad M. Alhajeri, A. H. Alenezi, Abdulrahman Almutairi, Ayedh Alajmi

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A computational investigation has been undertaken to study fluid flow through roughened tube with turbulators. Such flows are of particular interest in cooling internally high pressure turbine blades. Turbulators are fixed in each side of the passage (tube) to promote turbulence and enhance heat transfer. The tube had an aspect ratio of 1 and the position of the ribs closest to the bend are at 0.45d from the entrance and exit of the bend. The aim of this study is to examine the tube roughened by turbulator by studying some flow parameters upstream and downstream of the turbulator. It is cleared that the eddies sizes are decreased downstream in the first two turbulators and increased after the turbulators increases the turbulence in the tube and enhanced the heat transfer in the blade.

Keywords: fluid flow, turbulator, computation, blade

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Authors: Gozel Judakova, Markus Bause

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We present and analyze reliable numerical techniques for simulating complex flow and transport phenomena related to natural gas transportation in pipelines. Such kind of problems are of high interest in the field of petroleum and environmental engineering. Modeling and understanding natural gas flow and transformation processes during transportation is important for the sake of physical realism and the design and operation of pipeline systems. In our approach a two fluid flow model based on a system of coupled hyperbolic conservation laws is considered for describing natural gas flow undergoing hydratization. The accurate numerical approximation of two-phase gas flow remains subject of strong interest in the scientific community. Such hyperbolic problems are characterized by solutions with steep gradients or discontinuities, and their approximation by standard finite element techniques typically gives rise to spurious oscillations and numerical artefacts. Recently, stabilized and discontinuous Galerkin finite element techniques have attracted researchers’ interest. They are highly adapted to the hyperbolic nature of our two-phase flow model. In the presentation a streamline upwind Petrov-Galerkin approach and a discontinuous Galerkin finite element method for the numerical approximation of our flow model of two coupled systems of Euler equations are presented. Then the efficiency and reliability of stabilized continuous and discontinous finite element methods for the approximation is carefully analyzed and the potential of the either classes of numerical schemes is investigated. In particular, standard benchmark problems of two-phase flow like the shock tube problem are used for the comparative numerical study.

Keywords: discontinuous Galerkin method, Euler system, inviscid two-fluid model, streamline upwind Petrov-Galerkin method, twophase flow

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Authors: Takhchi Jamal, Ouisse Morvan, Sadoulet-Reboul Emeline, Bouhaddi Noureddine, Gagliardini Laurent, Bornet Frederic, Lakrad Faouzi

Abstract:

Structural intensity is a technique that can be used to indicate both the magnitude and direction of power flow through a structure from the excitation source to the dissipation sink. However, current analysis is limited to the low frequency range. At medium and high frequencies, a rotational component appear in the field, masking the energy flow and make its understanding difficult or impossible. The objective of this work is to implement a methodology to filter out the rotational components of the structural intensity field in order to fully understand the energy flow in complex structures. The approach is based on the Helmholtz decomposition. It allows to decompose the structural intensity field into rotational, irrotational, and harmonic components. Only the irrotational component is needed to describe the net power flow from a source to a dissipative zone in the structure. The methodology has been applied on academic structures, and it allows a good analysis of the energy transfer paths.

Keywords: structural intensity, power flow, helmholt decomposition, irrotational intensity

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Authors: Abbasali Abouei Mehrizi, Hamid Hassanzadeh Afrouzi

Abstract:

Reducing the drag force increases the efficiency of the aircraft and its better performance. Flow control methods delay the phenomenon of flow separation and consequently reduce the reversed flow phenomenon in the separation region and enhance the performance of the lift force while decreasing the drag force and thus improving the aircraft efficiency. Flow control methods can be divided into active and passive types. The use of synthetic jets actuator (SJA) used in this study for NACA GA (W) -2 airfoil is one of the active flow control methods to prevent stall phenomenon on the airfoil. In this research, the relevant airfoil in different angles of attack with and without jets has been compared by OpenFOAM. Also, after achieving the proper SJA position on the airfoil suction surface, the simultaneous effect of two SJAs has been discussed. It was found to have the best effect at 12% chord (C), close to the airfoil’s leading edge (LE). At 12% chord, SJA decreases the drag significantly with increasing lift, and also, the average lift increase was higher than other situations and was equal to 10.4%. The highest drag reduction was about 5% in SJA=0.25C. Then, due to the positive effects of SJA in the 12% and 25% chord regions, these regions were considered for applying dual jets in two post-stall angles of attack, i.e., 16° and 22°.

Keywords: active and passive flow control methods, computational fluid dynamics, flow separation, synthetic jet

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Authors: Pei-Syuan Ruan, Ya-Chi Yu, Shao-Wen Chen, Jin-Der Lee, Jong-Rong Wang, Chunkuan Shih

Abstract:

This study investigated the void fraction characteristics under low superficial gas velocity (J_g) and low superficial fluid velocity (J_f) conditions in a 3x3 rod bundle geometry. Three arrangements of conductivity probes were set to measure the void fraction at various cross-sectional regions, including rod-gap, sub-channel and rod-wall regions. The experimental tests were performed under the flow conditions of J_g = 0-0.236 m/s and J_f = 0-0.142 m/s, and the time-averaged void fractions were recorded at each flow condition. It was observed that while the superficial gas velocity increases, the small bubbles started to cluster together and become big bubbles. As the superficial fluid velocity increases, the local void fractions of the three test regions will get closer and the bubble distribution will be more uniform across the cross section.

Keywords: conductivity probes, rod bundles, two-phase flow, void fraction

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Authors: Minho Bang, Seok Min Choi, Jun Su Park, Hokyu Moon, Hyung Hee Cho

Abstract:

Present study investigates the effect of unsteady wakes on heat transfer in blade tip. Heat/mass transfer was measured in blade tip region depending on a variety of strouhal number by naphthalene sublimation technique. Naphthalene sublimation technique measures heat transfer using a heat/mass transfer analogy. Experiments are performed in linear cascade which is composed of five turbine blades and rotating rods. Strouhal number of inlet flow are changed ranging from 0 to 0.22. Reynolds number is 100,000 based on 11.4 m/s of outlet flow and axial chord length. Three different squealer tip geometries such as base squealer tip, vertical rib squealer tip, and camber line squealer tip are used to study how unsteady wakes affect heat transfer on a blade tip. Depending on squealer tip geometry, different flow patterns occur on a blade tip. Also, unsteady wakes cause reduced tip leakage flow and turbulent flow. As a result, as strouhal number increases, heat/mass transfer coefficients decrease due to the reduced leakage flow. As strouhal number increases, heat/ mass transfer coefficients on a blade tip increase in vertical rib squealer tip.

Keywords: gas turbine, blade tip, heat transfer, unsteady wakes

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Authors: Thendiyath Roshni, Stefano Pagliara

Abstract:

Block ramps (BR) or rock chutes are eco-friendly natural river restoration structures. BR are made of ramp of rocks and flows over BR develop turbulence and helps in the entrainment of ambient air. These act as natural aerators in river flow and therefore leads to oxygenation of water. As many of the hydraulic structures in rivers, hinders the natural path for aquatic habitat. However, flows over BR ascertains a natural rocky flow and ensures safe and natural movement for aquatic habitat. Hence, BR is considered as a better alternative for drop structures. As water quality is concerned, turbulent and aerated flows over BR or macro-roughness conditions improves aeration and thereby oxygenation. Hence, the objective of this paper is to study the oxygenation in the turbulent flows over BR. Experimental data were taken for a slope (S) of 27.5% for three discharges (Q = 9, 15 and 21 lps) conditions. Air concentration were measured with the help of air concentration probe for three different discharges in the uniform flow region. Oxygen concentration is deduced from the air concentration as ambient air is entrained in the flows over BR. Air concentration profiles and oxygen profiles are plotted in the uniform flow region for three discharges and found that air concentration and oxygen concentration does not show any remarkable variation in properties in the longitudinal profile in uniform flow region. An empirical relation is developed for finding the average oxygen concentration (Oₘ) for S = 27.5% in the uniform flow region for 9 < Q < 21 lps. The results show that as the discharge increases over BR, there is a reduction of oxygen concentration in the uniform flow region.

Keywords: aeration, block ramps, oxygenation, turbulent flows

Procedia PDF Downloads 154