Begell House Inc.
International Journal of Fluid Mechanics Research
FMR
2152-5102
42
4
2015
Development of Streamwise Vortices in Unsteady Circular Couette Flow
281-300
L. V.
Tkachenko
Institute of Hydromechanics of National Academy of Sciences of Ukraine 8/4, Zhelyabov St., 03680, Kyiv-180, MSP, Ukraine
N. S.
Gorodetskaya
Institute of Hydromechanics of National Academy of Sciences of Ukraine 8/4, Zhelyabov St., 03680, Kyiv-180, MSP, Ukraine
V. I.
Nikishov
Institute of Hydromechanics of National Academy of Sciences of Ukraine 8/4, Zhelyabov St., 03680, Kyiv-180, MSP, Ukraine
The results of numerical simulation of the development of streamwise Gortler vortices formed in unsteady circular Couette flow are represented. The vortices are initialized by injection of artificial vortical disturbances at given place of flow and at given instant of time. The problem of receptivity of the boundary layer in respect to the external disturbances is considered. The influence of the initial energy of disturbances, their wavelength, the location of input point and time of injection on the vortex characteristics are analyzed. A "cascade" mechanism of transport of disturbances from stability zone to the boundary layer has been identified. The features of formation and development of mushroom-shaped structures, in particular their uneven growth in transversal direction and subsequent increase of wavelength (Eckhaus instability) are explored.
Criticality of Appreciating Non-Newtonianivity in Plastic Injection Mould Conduit Design
301-314
Muralidhar
Lakkanna
Department of Mechanical Engineering, National Institute of Technology Karnataka Surathkal, 575025, India
Ravikiran
Kadoli
Department of Mechanical Engineering, National Institute of Technology Karnataka Surathkal, 575025, India
G. C. Mohan
Kumar
Department of Mechanical Engineering, National Institute of Technology Karnataka Surathkal, 575025, India
The prime intention of this research was to emphasise criticality of Non-Newtonian injectant behaviour to design ideal runner conduits for plastic injection moulds. Power-law constitutive relation was representatively adopted so shear thinning index could contrast, both Non-Newtonian and Newtonian behaviours together. An a priori analytical solution was developed from Power-law constitutive relation analogous to celebrated Hagen-Poiseuille solution for tubular runner conduits. This solution leveraged the computational intelligence advantage to enable a design criteria for perfect injection into impression gap synchronising injector capacity, injectant character as well as desired moulding features. The proposed design criteria readily adapts in practise including extremely complicated feed system configurations. Further to incorporate comprehensiveness, continuous sensitivity method was also adopted to discriminate cruciality over an infinite dimension scale, which lead insight into various important aspects that would certainly form a basis to diagnose filling issues reasoning several defects. For representation a sample set of runners from realistic, productive moulds that were initially designed with Newtonian hypothesis and later during trails heuristically optimised were compared, interestingly, they were statistically skewed towards runner sizes that were directly determined appreciating Non-Newtonian injection behaviour. Therefore, it was concluded that Non-Newtonian injection behaviour should have significant prominence in injection mould design criteria.
Effects of Thermal Radiation and Chemical Reaction on Steady MHD Mixed Convective Flow over a Vertical Porous Plate with Induced Magnetic Field
315-333
Dipak
Sarma
Department of Mathematics, Cotton College (Gauhati University) Guwahati-781001, Assam, India
Kamalesh K.
Pandit
Department of Mathematics, Cotton College (Gauhati University) Guwahati-781001, India; Department of Mathematics, PDUAM, Eraligool
Karimganj 788723, Assam, India
The objective of the present study is to investigate the effect of chemical reaction and radiation on the laminar mixed free-force convection flow of a viscous incompressible electrically conducting fluid above a vertical porous plate under the action of a transverse applied magnetic field. The governing non-dimensional equations relevant to the problem, containing partial differential equations are simplified first by Boussinesq's approximation and are transformed by usual similarity transformations into a system of coupled non-linear ordinary differential equations. In the presence of transverse magnetic field, the dimensionless governing equations are solved analytically by using regular perturbation technique with Eckert number Ec << 1 as perturbation parameter. The effects of thermal radiation and chemical reaction are taken into account in presence of induced magnetic field. Under certain assumptions, the solution for velocity field, temperature distribution, concentration field and induced magnetic field to the second approximations are obtained. The influences of the various parameters entering into the problem on the velocity, temperature and concentration fields and on induced magnetic fields are studied graphically. It is found that the magnitude of the velocity, the temperature and the induced magnetic field are reduced considerably with a rise in the radiation parameter N or the chemical reaction parameter K or the magnetic parameter M. Also, an increase in the chemical reaction parameter K produces a decrease in the concentration of the fluid flow. The effects of various parameters on the skin friction coefficient τ, Nusselt Number Nu and Sherwood Number Sh are presented in tabular form.
Unsteady Two-Phase Flow in a Catheterized Artery with Atherosclerosis
334-354
Ranadhir
Roy
School of Mathematical and Statistical Sciences,
One West University Boulevard, University of Texas Rio Grande Valley, Brownsville, Texas 78520 USA
Jorge
Cisneros
University of Texas-Pan American, Department of Mathematics Edinburg, Texas, USA
Daniel N.
Riahi
School of Mathematical and Statistical Sciences,
One West University Boulevard, University of Texas Rio Grande Valley, Brownsville, Texas 78520 USA
In this paper we investigate the effect of oscillating axisymmetric blood flow on a catheterized artery in the presence of atherosclerosis, which is obtained from the available experimental data. The oscillatory (unsteady) blood flow in the arterial tube is formulated as 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 by using analytical and computational methods. The important quantities such as plasma speed, velocity of red cells, blood pressure force, impedance (blood flow resistance) and the wall shear stress are computed for different values of the catheter size and hematocrit due to the red cells. We calculate dependence of these quantities on the temporal and spatial variable as well as on the frequency of the flow oscillation. We find, in particular, that the higher value of the frequency, larger catheter size, and higher values of hematocrit can lead to higher values of axial velocity, the impedance and the wall shear stress in the stenosis zone.
Eulerian Modeling of Gas-Solid Flow with Solid Volume Fraction up to 0.1
355-373
Brundaban
Patro
National Institute of Technology Warangal, Telangana 506004, India
This paper presents the results related to the CFD simulations using the two-fluid model approach to study the effects of solids volume fraction and gas phase Reynolds number on the pressure drop in a fully developed gas-solid flow. A horizontal pipe of internal diameter 30 mm and length 3 m is considered for this study. The Gidaspow drag model with algebraic granular temperature model is used for the simulations. Numerical results are compared with the bench mark experimental data, and good agreement is found with a maximum deviation of −20 %. The solids volume fractions ranging from 0.01 to 0.1 and gas phase Reynolds numbers ranging from 20000 to 100000 are used in the present study. The numerical results indicate that the magnitude of the pressure drop is higher for higher values of the solids volume fraction and gas phase Reynolds number.