Begell House Inc.
International Journal of Fluid Mechanics Research
FMR
2152-5102
41
1
2014
Large Eddy Simulation of the Flow across a Rotating Circular Cylinder
1-15
Kamran
Mobini
Department of Mechanical Engineering, Shahid Rajaee Teacher Training University Lavizan, Tehran, Iran
M.
Niazi
Department of Mechanical Engineering, Shahid Rajaee Teacher Training University Lavizan, Tehran, Iran
Turbulent flow across a rotating circular cylinder is numerically investigated for five Reynolds numbers and five rotational speeds. Large Eddy Simulation (LES) method with Smagorinsky subgrid scale model is used for this purpose. Variations of the aerodynamics forces and the flow structure with spin ratio and Reynolds number are studied. The results showed that for the range of studied Reynolds numbers, drag force decreases with both spin ratio and Reynolds number, but lift force increases with spin ratio and decreases with Reynolds number. In case of flow structure, both the front stagnation point and the top separation point dislocate upward along the cylinder by increase of spin ratio and decrease of Reynolds number. Size of the vortices behind the cylinder is increased with both spin ratio and Reynolds number. Comparison of the LES results with the results from the other numerical or experimental works showed an acceptable correspondence. It is concluded that the LES method can be applied to highly recirculating flows with good level of accuracy and low computational cost.
Two-Phase Blood Flow and Heat Transfer in an Inclined Stenosed Artery with or without a Catheter
16-30
Ani E.
Garcia
Department of Mathematics, University of Texas-Pan American Edinburg, TX, USA
Daniel N.
Riahi
School of Mathematical and Statistical Sciences,
One West University Boulevard, University of Texas Rio Grande Valley, Brownsville, Texas 78520 USA
We investigate the problem of blood flow and heat transfer in an inclined artery with or without a catheter and in the presence of stenosis in the artery whose shape is based on the available experimental data. The presence of stenosis that locally thickens the artery wall is a result of fatty materials such as cholesterol. The use of catheter is important as a standard tool for diagnosis and treatment in patience whose artery is affected adversely by the presence of atherosclerosis within the artery. The blood flow in the arterial tube is represented by a two-phase model composing a suspension of erythrocytes (red cells) in plasma. The coupled differential equations for both fluid (plasma) and particles (red cells) are solved theoretically subjected to reasonable modeling and approximations. The important quantities such as blood pressure force, impedance (blood flow resistance), blood temperature and the heat flux on the artery are computed in the presence or absence of the catheter, and in the presence of the axially located stenosis, gravity and the hematocrit due the red cells-plasma combination of the blood flow.
Numerical Investigation of Turbulent Premixed Methane/Air Jet Flame Using Peters and Williams Reduced Mechanism
31-50
Mourad
Chekired
Laboratoire d'Energetique Appliquee et de Pollution, Universite Constantine 1, Algeria
Zoubir
Nemouchi
Laboratoire d'Energetique Appliquee et de Pollution, Université des Frèses Mentouri, Constantine, Algeria
M. S.
Boulahlib
Laboratoire d'Ingenierie des Transports et Environnement, Universite Constantine 1, Algeria
A RANS based numerical investigation of the Bunsen jet flame F3 is presented and assessed using the moment methods combined with the two-step reduced mechanism derived from the four-step global mechanism of Peters and Williams. The basic argument adopted in this study is that the activation energies of the reaction rates of the two-step reduced scheme are rather small. To validate the flow solver as well as to capture combustion effect on the mean flow field, the simulations are performed, as a first step, for the cold jet. The reactive jet is then calculated where the investigation is focused on the dynamic, thermal and the species mass fractions mean fields in the considered flame. The results show that a reasonable agreement with measurements and previous numerical predictions is found where a representative structure of the flame is consequently identified.
Swirl Atomizer Design for Evaporative Cooling of High Temperature Compressed Air Stream
51-70
Uzair Ahmed
Dar
School of Mechanical Engineering, Northwestern Polytechnical University Xi'an, Shaanxi, China; Faculty of Mechanical Engineering GIK Institute of Engineering Sciences and Technology, Pakistan
Mykola
Bannikov
Faculty of Mechanical Engineering GIK Institute of Engineering Sciences and Technology, Pakistan
This work presents the design of a swirl atomizer which provides a certain flow rate of water with required spray quality for effective evaporative cooling of high temperature compressed air of a turbocharged diesel engine. By using wet compression theoretical model, the desired mass flow rate of water and quality of spray for effective evaporation was determined. The evaporative cooling decreases the intake air temperature of engine and increases its mass flow rate, with constant fuel-to-air ratio this increase in air mass flow rate increases the power of the engine. Abramovich's theory along with Kliachko's theory was followed to design a swirl atomizer that provides the required spray characteristics. Information has been presented on the effect of atomizer inlet port geometry, swirl chamber design, orifice design and the importance of swirling inside atomizer. The effects of atomizer geometric parameters such as angle of conical convergence, length-to-diameter ratio of inlet port and of swirl chamber were examined. It was concluded that the length-to-diameter ratio of swirl chamber has a significant effect on atomizer flow rate and spray cone angle determination. With the same injection pressure, its increase leads to enhancing the mass flow rate while decreasing the spray cone angle from the atomizer. The atomizer was tested experimentally and through fluid flow modeling for its required spray quality and the results were fairly close with theoretically predicted results. The design of atomizer was also optimized for required spray characteristics by modeling the fluid flow inside the atomizer.
Unsteady MHD Free Convection Flow Near a Moving Vertical Plate with Ramped Wall Temperature
71-90
Kalidas
Das
Department of Mathematics, Kalyani Government Engineering College, Kalyani, W.B., Pin-741235, India
S.
Jana
Department of Mathematics, Jadavpur University Kolkata 700032, West Bengal, India
Prabir Kumar
Kundu
Department of Mathematics, Jadavpur University, Kolkata 700032, W.B., India
The problem of unsteady free convection flow and mass transfer of a viscous, electrically conducting incompressible fluid in the presence of thermal radiation and under the influence of transverse magnetic field to an infinite vertical plate with ramped wall temperature which moves with time dependent velocity is studied. The aim of the present study is to characterize the effects of ramped wall temperature, radiative parameter, Schmidt number etc on the flow properties. The governing equations are solved analytically using Laplace transform technique. Some important applications of physical interest for different type motion of the plate are discussed. The variations in fluid velocity, temperature and concentration are shown graphically whereas numerical values of skin friction and rate of heat transfer are presented in tabular form for pertinent parameters to show interesting aspects of the solution.