Begell House Inc.
International Journal of Fluid Mechanics Research
FMR
2152-5102
34
4
2007
Numerical Analysis of Grashof and Darcy Number Effects on Dissipative Natural Convection Boundary Layers in a Micropolar Fluid-Saturated Geological Porous Medium
287-307
O. Anwar
Bég
Fluid Mechanics, Nanosystems and Propulsion, Aeronautical and Mechanical Engineering,
School of Computing, Science and Engineering, Newton Building, University of Salford,
Manchester M54WT, United Kingdom
Rama
Bhargava
Department of Mathematics, Indian Institute of Technology, Roorkee-247667, India
S.
Rawat
Department of Mathematics, Indian Institute of Technology, Roorkee, India
Harmindar S.
Takhar
Engineering Department, Manchester Metropolitan University, Oxford Rd., Manchester, M15GD, UK
Tasveer A.
Beg
Engineering Mechanics Associates, Manchester, M16, England, United Kingdom
The thermo-micropolar non-Newtonian theory is used to formulate a transport model for combined free convection heat and species transfer through a micropolar-fluid saturated Darcian porous medium. Temperatures in the medium are assumed to be high enough for viscous heating effects to be significant. The influence of thermal Grashof number, species Grashof number and Darcian porous number on the momentum, angular momentum, temperature and concentration flow fields are studied using the finite element method. Temperature is observed to be reduced with a rise in the thermal Grashof number. Species transfer is seen to be also decreased with increasing species Grashof number. Micro-rotation values are also decreased with both thermal and species Grashof numbers near the stretching surface and also depressed with a rise in the Darcy number in the near-field regime. The flow field is accelerated with a rise in Darcy number as indicated by the increase in translational velocities. Our computations are relevant to for example the diffusion of hydrogen gas in air-saturated porous materials, pollutant release in a geophysical regime etc.
Numerical Investigations of Compressible Flow and Energy Separation in a Counter-Flow Vortex
308-331
Pongjet
Promvonge
Department of Mechanical Engineering, Faculty of Engineering, King Mongkut's Institute of Technology Ladkrabang, Bangkok 10520, Thailand
Smith
Eiamsa-ard
Mahanakorn University of Technology
This paper presents a numerical modelling of the strongly swirling turbulent compressible flow and temperature/energy separation in a counter-flow vortex tube. A comprehensive two-dimensional vortex tube model is developed which incorporates an algebraic Reynolds stress model (ASM). Computations, based on a finite volume method, were carried out by utilising the k-ε model and the ASM for the closure of the second-order correlation moments in the governing equations. The modelling of turbulence for compressible, complex flows used in the simulation is discussed. The numerical results for a counter-flow vortex tube describe the detailed characteristics of the axial/tangential velocity, static/total pressure, static/total temperature fields based on the k-ε model and the ASM, which are the important to design and operation of the vortex tube.
Unsteady Flow Behind Forward Swept Axial Compressor Rotors
332-351
Mukka
Govardhan
Thermal Turbomachines Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Madras Chennai, India
O. G. Krishna
Kumar
Thermal Turbomachines Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600 036, India
N.
Sitaram
Thermal Turbomachines Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600 036, India
The experimental investigations are conducted to improve the understanding of the complex flow pattern at the exit of forward and unswept axial compressor rotors. The unsteady flow pattern behind the experimental rotors was studied by a novel method using fast response probe. The data acquisition and post processing of the unsteady data was done using virtual instrumentation system. Forward swept rotor with 10° sweep showed improved pressure rise and efficiency compared to baseline unswept rotor. On the other hand, 20° forward swept rotor exhibited increased operating range and stall margin but at the expense of pressure rise. The wake pattern in the midspan regions with forward sweep indicated higher wake width and wake defect due to the high deceleration of the blade boundary layer flow brought about by the spanwise streamline shift. The reduction in wake width and wake defect with forward sweep near the hub suggests that the mixing loss near the hub is reduced.
Marangoni Convection in a Composite Porous Layer and a Fluid Layer with a Deformable Free Surface
352-373
Krishna B.
Chavaraddi
UGC-Centre for Advanced Studies in Fluid Mechanics, Department of Mathematics, Bangalore University, Bangalore-560 001, India
The linear stability analysis of Marangoni convection in a composite system comprised of an incompressible fluid-saturated porous layer underlying a layer of the same fluid is considered. The upper fluid surface, free to the atmosphere, is considered to be deformable and subjected to temperature-dependent surface tension. The fluid flow in the porous layer is governed by the Forchheimer-extended-Darcy equation, and both Beavers-Joseph and Jones conditions are employed at the interface between the two layers. The resulting eigenvalue problem is solved exactly and also by the regular perturbation technique when the boundaries of the system are insulated to temperature perturbations. The effect of the crispation number, Bond number, and the other physical parameters involved therein are analyzed for the stability of the system. It is found that a decrease in the crispation number and an increase in the Bond number delay the onset of convection. Also, the effect of the ratio of the fluid to the porous layer thickness along with the other physical parameters on the control (suppress or augment) of convection is analyzed in detail.
Influence of Wall Properties on Perstalsis in the Presence of Magnetic Field
374-386
D.
Srinivasacharya
Department of Mathematics, National Institute of Technology, Warangal-506004,
India
G
Radhakrishnamacharya
Ch.
Srinivasulu
Department of Mathematics, National Institute of Technology, Warangal - 506 004 (A.P.) India
The interaction of peristaltic transport of an incompressible Newtonian viscous fluid in a two-dimensional uniform channel, with the elasticity of the flexible walls has been studied in the presence of transverse magnetic field. Using long wavelength approximation, perturbation solutions have been obtained in terms of wall slope parameter. The effects of various elastic parameters, magnetic parameter, Reynolds number and geometric parameter on streamline pattern and average flux have been studied. The phenomenon of trapping has been observed and it is found that the area of the trapped bolus increases with tension parameter, damping and mass concentration parameters. The flux is negative for all values of elastic and geometric parameters.