Begell House Inc.
International Journal of Fluid Mechanics Research
FMR
2152-5102
36
6
2009
Thermophoresis Effects on Heat and Mass Transfer in MHD Flow Over a Vertical Stretching Surface with Radiation
489-501
Ahmed Y.
Bakier
Department of Mathematics, Assiut University, Assiut, Egypt
This paper deals with the effects of thermophoresis particle deposition, radiation and magnetic field on the flow, heat and mass transfer characteristics in a combined convective boundary layer flow over a stretching vertical plate. The governing boundary layer equations are transformed to a dimensionless form by similarity transformations. The transformed coupled nonlinear ordinary differential equations are solved numerically by using the shooting method. The effects of different parameters on the dimensionless velocity, temperature, and concentration profiles are shown graphically. In addition, tabulated results for the local skin-friction coefficient, the local Nusselt number, and the local Sherwood number are presented and discussed.
Generation of Water Waves by a Line Source in Presence of Surface Tension
502-512
Prabir Kumar
Kundu
Department of Mathematics, Jadavpur University, Kolkata 700032, W.B., India
Partha
Agasti
Department of Mathematics, Debipur Milan Vidyapih, Debipur, Purba Medinipur, West Bengal, Kolkata-721650, INDIA
Present study is concerned with the generation of water waves by an oscillating line source in the presence of a nearly vertical cliff in deep water. Corrections upto first order to the wave amplitude at infinity and the velocity potential have been found in terms of integrals involving the shape function of the cliff by using a technique, essentially, based on the standard perturbation theory, assuming the surface tension effect at the free surface. Assuming two particular shapes of the nearly vertical cliff, these corrections have also been found.
Pressure Fluctuations in the Flow Through a Low Aspect Ratio Dump Combustor with Tapered Exit
513-523
Abhijit
Kushari
Department of Aerospace Engineering, IIT Kanpur, Kanpur-208 016, Uttar Pradesh, India
Srinibas
Karmakar
Re-circulating flows are established in dump combustors at the dump plane due to the sudden expansion. However, given enough length, the separated flow at the dump plane attaches itself inside the combustor and a fully developed, non-circulating, attached flow field is established. But, if the length of the combustor is less than the free-stream reattachment length, then the flow does not re-attach inside the combustor. Instead, a portion of the flow is reflected from the exit section, causing stronger re-circulation that modifies the flow structure inside the combustor. This paper describes an experimental study of turbulent flow field inside a dump combustor for a range of flow Reynolds numbers. The focus of this effort is to study the interaction between the flow re-circulation and the large-scale turbulence. Detailed measurements of the wall pressure transients were taken using strain-gage pressure sensors. The fluctuating component of the pressure was isolated and analyzed. The signals were analyzed using FFT, Auto-Correlation and Cross-correlation to distinguish the re-circulating flow and the large-scale turbulence. The re-circulating flow, identified by low frequency fluctuations in pressure (∼ 0.5 Hz), was seen to be strongest inside the combustor almost half way through the combustor length. At the same time, the large-scale turbulence intensity (identified by high frequency fluctuations in the range of 460 Hz) level is seen to be lower inside the combustor than in the incoming pipe. This can be attributed to the turbulence cascading due to the re-circulating flow, which increases the small-scale energy and reduces the large-scale energy.
Free Convective Heat and Mass Transfer in a Doubly Stratified Porous Medium Saturated with a Power-Law Fluid
524-537
P. A. Lakshmi
Narayana
Department of Mathematics, Indian Institute of Technology Hyderabad, Hyderabad - 502205, Telangana, India
P. V. S. N.
Murthy
Department of Mathematics, Indian Institute of Technology, Kharagpur, West Bengal, 721302, India
P. V. S. S. S. R.
Krishna
Post Graduate Teacher, Kendriya Vidyalaya - Ajni, Nagpur, 440004, Maharastra, India
Adrian
Postelnicu
Department of Thermal Engineering and Fluid Mechanics, Transilvania University of Brasov, Brasov, Romania
Free convection heat and mass transfer of non-Newtonian power law fluid from a vertical surface embedded in a doubly stratified Darcy porous medium has been analyzed. The wall temperature and concentration are constant and the medium is linearly stratified in the vertical direction with respect to both temperature and concentration. A series approximation is made for stream function, temperature and concentration in terms of thermal stratification parameter. The flow, temperature and concentration fields are affected by the complex interactions among the diffusion ratio Le, buoyancy ratio N and stratification ratio Sr. The effects of power law index parameter and double stratification of the medium on non-dimensional heat and mass transfer coefficients is discussed.
Effect of Additive on the Rheological Characteristics of Slurries of Fly Ash and Bottom Ash Mixture at High Concentrations
538-551
Sunil
Chandel
Applied Mechanics Department, Indian Institute of Technology, Delhi-110016, India
S. N.
Singh
Department of Applied Mechanics, IIT Delhi Hauz Khas, New Delhi, India
V.
Seshadri
Department of Applied Mechanics, IIT Delhi Hauz Khas, New Delhi, India
Present study reports the rheological characteristics of slurries of mixture of fly ash and bottom ash slurry at high concentrations (above Cw ≈ 60 % by weight) with and without additive. The ratio of fly ash and bottom ash is kept at 4:1. Mixture of Sodium Carbonate and Henko detergent has been used as the additive. Rheological tests on slurries (with and without additive) were carried out in a Weissenberg Rheogoniometer with concentric cylinder platens. The variation of shear stress τ with shear rate γ shows that the mixture of fly ash and bottom ash slurries above a solid concentration of 40 % by weight show non-Newtonian behavior and that the experimental data fits a simple Bingham plastic model. Addition of additive results in a significant decrease in the yield stress and Bingham viscosity at all concentrations tested.
Solutions to the Brinkman - Forchheimer Momentum Equation for a Unidirectional Flow over a Rectangular Domain
552-565
Robert
Van Gorder
Department of Mathematics, University of Central Florida, Orlando, FL 32816, USA
Kuppalapalle
Vajravelu
University of Central Florida
Fahir
Akyildiz
University of Gaziantep
Analytical solutions to the semi-linear Brinkman-Forchheimer momentum equation are obtained using the method of Rayleigh-Ritz. The obtained results are in good agreement with the asymptotic results obtained in this paper and with those available in the literature. Furthermore, we discuss the effects of the various physical parameters on the fluid flow in a porous duct. Of all the parameters, the adverse pressure gradient G has the strongest effect in increasing the fluid velocity.
A New Correlation for Entropy Generation in Low Reynolds Number Turbulent Shear Layers
566-572
Edmond J.
Walsh
Stokes Research Institute, Mechanical and Aeronautical Engineering Department, University of Limerick, Limerick, Ireland
Donald M.
McEligot
Aerospace and Mechanical Engineering Department, University of Arizona,Tucson, AZ 85721; Idaho National Laboratory (INL), Idaho Falls, ID 83415-3885, USA; and Institut für Kernenergetik und Energiesysteme, Universitat Stuttgart, Stuttgart, Germany
The need to quantify entropy generation rates is critical to optimizing the performance of many engineered systems. However, accurate predictions and measurement of this quantity are difficult. Recent direct numerical simulations (DNS) are employed to develop a new correlation for the entropy generation at low and moderate Reynolds numbers typical of those found on turbomachinery surfaces for example. Such a correlation is only possible due to advances in computing, that have allowed moderate Reynolds numbers to be simulated. The result illustrates the discrepancies of existing correlations used throughout the literature for predicting entropy generation rates in low Reynolds number turbulent flows.
Effect of Peripheral Layer on Peristaltic Transport of a Couple Stress Fluid
573-583
K. Maruthi
Prasad
Department of Mathematics and Humanities, National Institute of Technology, Warangal-506004,India
G
Radhakrishnamacharya
Peristaltic transport of a two fluid model with couple stress fluid in the core region and Newtonian fluid in the peripheral layer is considered. Using the long wavelength approximation, the equations governing the flow are solved and closed form expressions for pressure rise and time averaged flux have been obtained. The effects of various parameters on these flow variables have been studied. It is found that pressure rise increases with couple stress fluid parameter and viscosity ratio, but decreases with mean radius of central layer. However, the fric-tional force decreases with viscosity ratio.