Begell House Inc.
International Journal of Fluid Mechanics Research
FMR
2152-5102
45
5
2018
EFFECT OF DIMENSIONS OF VARIOUS SPIKES OF A SPIKED CYLINDER ON THE BUZZ PHENOMENON SUBJECTED TO HYPERSONIC FLOWS
377-388
R.
Rajesh
Department of Mechanical Engineering Amrita School of Engineering, Bengaluru Amrita
Vishwa Vidyapeetham, India
Sirangala Ganesh
Rakesh
Department of Mechanical Engineering, Amrita School of Engineering, Bengaluru, Amrita
Vishwa Vidyapeetham, India, 560035
Transient numerical analysis has been carried out by simulating the fluid flow over sharp, conical, blunt, hemispherical, and aerodisk spiked cylinders. They have been subjected to hypersonic flow of Mach number 6.1, at zero angle of attack, so as to investigate the variations of frequency and thus the Strouhal number during hypersonic buzz phenomenon at various L/D ratios by capturing the flow unsteadiness using Ansys Fluent solver. It has been concluded that the frequency of hypersonic buzz is maximum at a particular L/D ratio known as the critical L/D ratio, which is unique for each type of spike. Above the critical L/D ratio, the buzz frequency decreases almost linearly with an increase in the L/D ratio, and below the critical L/D ratio, the frequency decreases drastically with a reduction in L/D, and finally the hypersonic buzz ceases to occur below a certain L/D ratio for every type of spiked body. Analysis of the aerodisk spiked cylinder revealed no hypersonic buzz phenomenon for any practical L/D ratios. Further, the correspondence between CD and pressure history at the probe point has also been verified.
THERMAL INSTABILITY OF HOT FERROFLUID LAYER WITH TEMPERATURE-DEPENDENT VISCOSITY
389-398
Joginder Singh
Dhiman
Department of Mathematics, Himachal Pradesh University, Summer Hill, Shimla, Himachal
Pradesh 171005, India
Nivedita
Sharma
Department of Mathematics, Himachal Pradesh University, Summer Hill, Shimla, Himachal
Pradesh 171005, India
In this paper stability analysis of the ferrofluid layer heated from below when viscosity is temperature dependent
is carried out analytically for the general nature of bounding surfaces. Using the analytical method of Pellew and
Southwell [Proc. Roy. Soc. A, vol. 176, pp. 312–343, 1940] of conjugate eigenfunctions, the principle of exchange of
stabilities (PES) is proved to be valid for the problem for very small values of magnetic parameter. This result yields
that the ferroconvection is through the stationary mode only and the result is uniformly valid whether viscosity is
temperature dependent or constant. However, for certain classes of hot fluids (in some astrophysical situations) the
magnetic parameter can have large values, and this quantitative effect has a qualitative effect on the instability of ferrofluids. It is shown here that for large values of magnetic parameter oscillatory instability can exist and hence the bounds for the growth rate of unstable oscillatory modes of the problem are also derived herein.
ESTIMATION OF EFFECTIVE LENGTH ALONG WITH FLOW AND PRESSURE CHARACTERISTIC ANALYSES OF A SUDDEN EXPANSION DIFFUSER AND A HYBRID DIFFUSER
399-412
Ashim
Guha
Department of Mechanical Engineering, Indian Institute of Engineering Science and
Technology, Shibpur, Howrah—711 103, West Bengal, India
Dipak Kumar
Mandal
Deptartment of Mechanical Engineering, College of Engineering & Management, Kolaghat,
P.O: K.T.P.P. Township, Midnapore (E) - 721171, West Bengal, India
Nirmal Kumar
Manna
Department of Mechanical Engineering, Jadavpur University Kolkata, 700032, West Bengal, India
Somnath
Chakrabarti
Department of Mechanical Engineering, Indian Institute of Engineering Science and Technology Shibpur, Howrah, 711103, West Bengal, India
In this paper, the performance simulation of a sudden expansion diffuser and a hybrid diffuser has been carried out. The two-dimensional steady differential equations for conservation of mass and momentum have been solved for Reynolds numbers ranging from 50 to 600. During the simulation, a fixed aspect ratio of 2 has been considered for both diffuser geometries, and a fixed value of half divergence angle of 3.5° has been considered for the hybrid diffuser. At the inlet, a fully developed velocity profile has been used. The effect of Reynolds number on streamline contours and average static pressure has been studied in detail and compared between two diffuser geometries. The effective diffuser lengths for achieving maximum average static pressure at the diffuser exit have been computed for the considered Reynolds numbers.
A NUMERICAL INVESTIGATION OF SLIP FLOW THROUGH CIRCULAR MICRO-CHANNEL
413-423
Santosh Kumar
Singh
Department of Mechanical Engineering, SRM Institute of Science and Technology,
Kattankulathur, Chennai 603203, India
Vijay Kumar
Pal
Department of Mechanical Engineering, SRM Institute of Science and Technology,
Kattankulathur, Chennai 603203, India
Koustuv
Debnath
Department of Aerospace Engineering and Applied Mechanics, Indian Institute of Engineering
Science and Technology, Shibpur 603203, India
Fluid flow in micro-channel is a major area of research, due to its wide area of applications in various forms in industries. Although substantial works have been carried out experimentally, numerically as well as analytically in this
area, still the reported results show a wide variation from one another. In the present work, an attempt has been made to consider the problem of gas flow in circular micro-channel under conditions of varying Knudsen number (Kn = 0.001–0.1), which corresponds to continuum model. The observation is confined to the laminar zone only and fluid properties have been assumed to be constant. The momentum equation has been converted into stream function-vorticity form and a finite difference technique has been used. Both slip and no-slip boundary conditions have been applied. The numerical scheme has been validated and the results have shown the importance of the Knudsen number on friction factor Reynolds product, pressure distribution in the gaseous flow during its hydro-dynamically developing stage. Also, a non-dimensional analysis has been presented.
HALL CURRENT EFFECTS ON HYDROMAGNETIC FLOW THROUGH UNIFORM CHANNEL BOUNDED BY POROUS MEDIA
425-438
K.
Ramakrishnan
Department of Mathematics, Karpagam College of Engineering, Othakkal Mandapam,
Coimbatore - 641 032, Tamilnadu, India
The steady, laminar, viscous, electrically conducting hydromagnetic flow through a channel of uniform width covered by porous media of infinite thickness is studied with Hall effects. The fluid is acted upon by the constant pressure gradient and a uniform magnetic field is applied in the direction perpendicular to the motion of the fluid. Closed form solution is obtained for the governing equations using Beavers–Joseph slip condition. Profiles of primary and
secondary velocities and shear stress have been computed for different values of porous parameter, Darcy velocity,
slip parameter, Hartmann number, and Hall parameter. It is observed that the porous parameter, slip parameter, and
Hartmann number produce a retarding effect on both the primary and secondary velocities. The Hall parameter has an
accelerating effect on both the velocities. It is noticed that the components of shear stress decreased in magnitude when the Hartmann number increases. It is also observed that the value of shear stress due to primary and secondary flows
increases in magnitude when the Hall parameter and slip parameter increase.
RADIATION ABSORPTION AND VISCOUS-DISSIPATION EFFECTS ON MAGNETOHYDRODYNAMIC FREE-CONVECTIVE FLOW PAST A SEMI-INFINITE, MOVING, VERTICAL, POROUS PLATE
439-458
K V B
RAJAKUMAR
Research scholar in Rayala seema university
K. S.
Balamurugan
Department of Mathematics, RVR & JC College of Engineering, Guntur, Andhra Pradesh,
India
Ch. V. Ramana
Murthy
Department of Mathematics, Sri Vasavi Institute of Engineering & Technology, Nanadamuru,
Andhra Pradesh, India
This article investigates radiation absorption and viscous-dissipation effects on magnetochydrodynamic free-convective
flow past a semi-infinite, moving, vertical, porous plate, with heat generation and chemical reaction (Kr). Flow is unsteady and restricted to the laminar domain. The dimensionless governing equations for this investigation are solved analytically using multiple regular perturbation law. The effects of various physical parameters on velocity, temperature (T), and concentration (C) fields are presented graphically. With the aid of the graphs, expressions for skin friction, Nusselt number, and Sherwood number profiles are provided with the use of tables. We find that increases in Kr, Schmidt number (Sc), Prandtl number, and thermal radiation results in decreased velocity and T. In addition, increases in both Kr and Sclead to decreased C. However, increases in porous medium, solutal Grashof number, and
radiation lead to increases in both velocity and T.
HEAT AND MASS TRANSFER ON UNSTEADY, MAGNETOHYDRODYNAMIC, OSCILLATORY FLOW OF SECOND-GRADE FLUID THROUGH A POROUS MEDIUM BETWEEN TWO VERTICAL PLATES, UNDER THE INFLUENCE OF FLUCTUATING HEAT SOURCE/SINK, AND CHEMICAL REACTION
459-477
M. Veera
Krishna
Department of Mathematics, Rayalaseema University, Kurnool, Andhra Pradesh - 518007,
India
Kamboji
Jyothi
Department of Mathematics, Rayalaseema University, Kurnool, Andhra Pradesh-518007,
India
Ali J.
Chamkha
Department of Mechanical Engineering, Prince Sultan Endowment for Energy and
Environment, Prince Mohammad Bin Fahd University, Al-Khobar 31952, Kingdom of Saudi
Arabia; RAK Research and Innovation Center, American University of Ras Al Khaimah, United Arab Emirates, 10021
We consider the unsteady, magnetohydrodynamic, oscillatory flow of an incompressible, electrically conducting,
second-grade fluid through a saturated, porous medium between two vertical plates that are under the influence of
a uniform, transverse, magnetic field normal to the plates, with heat source and chemical reaction. One plate of the
vertical channel is kept stationary, whereas the other is oscillating with uniform velocity; the two plates are subjected to constant injection and suction velocities, respectively. The flow through the porous medium is governed by the equation for Brinkman's model for momentum. The closed-form solutions of the governing equations are obtained for velocity, temperature, and concentration profiles, with use of the perturbation technique. The effects of various governing parameters on these three profiles are computationally discussed and graphically presented. Skin friction, Nusselt number, and Sherwood number are obtained analytically, and their behaviors are computationally discussed.