Begell House Inc.
International Journal of Fluid Mechanics Research
FMR
2152-5102
34
3
2007
Study of the Flow and Acoustic Fields in a Rigid-Walled Channel of Circular Cross-Section with a Local Axisymmetric Narrowing. Part 2. Numerical Results
191-209
A. O.
Borisyuk
Institute of Hydromechanics of the National Academy of Sciences of Ukraine, Zhelyabov Str., 8/4, 03680, Kyiv-180, MSP, Ukraine
The hydrodynamic and acoustic characteristics of the flow past a channel's local narrowing, obtained on the basis of the method developed in work [1], are estimated. The estimation results correlate well with the corresponding data reported in scientific literature. This indicates a successful testing of the developed method and allows applying it to solving the appropriate mechanical and acoustical problems.
Qualitative Study to Assess the Effect of a Subsurface Barrier on Contaminant Transport in Groundwater: Computation of Moments
210-223
Samir K.
Das
Department of Computational Fluid Dynamics, International Institute of Information Technology, P-14, Rajiv Gandhi Infotech Park, Hinjawadi, Pune- 411057, India
A. S.
Warke
Symbiosis Institute of Technology, Lavale Campus, Dynamics, Pune - 411 042, India
Rama Subba Reddy
Gorla
Department of Mechanical Engineering, Cleveland State University, Cleveland, OH, 44115 USA; Department of Mechanical Engineering, University of Akron, Akron, Ohio 44325, USA; Department of Mechanical & Civil Engineering, Purdue University Northwest, Westville, IN 46391, USA
This paper describes a numerical solution of solute transport in a hypothetical, homogeneous, isotropic aquifer under constant seepage velocity where the contaminant source is located at the bottom left-hand model boundary with finite length. On applying the alternate direction implicit method, the governing unsteady advective-dispersive equation is solved to obtain the time evolution of the contaminant plume for two scenarios: with the absence of a subsurface barrier and with the presence of a subsurface barrier at dimensionless distance X = 1.0 or 2.6. Model simulations are carried out for up to 16 years to assess the long-term effect, wherein we employ the method of moments to study important statistical parameters such as central moment, coefficients of skewness, and kurtosis. We approximate the mean concentration distribution by applying Edgeworth's asymptotic series for non-Gaussian curves involving Hermite polynomials. The forward displacement of centroid with time, and deviations of the mean concentration distribution from Gaussianity have been examined in both scenarios.
A Nonlinear Model for the Atomization of Attenuating Liquid Sheets
224-243
E. A.
Ibrahim
Mechanical Engineering Department, Tuskegee University, Tuskegee, Alabama 36088,USA
D.
Sree
Mechanical Engineering Department, Tuskegee University, Tuskegee, Alabama 36088, USA
T. R.
McKinney
Mechanical Engineering Department, Tuskegee University, Tuskegee, Alabama 36088, USA
The problem of predicting the characteristics of the spray produced by the disintegration of an attenuating liquid sheet emanated into a surrounding gas is considered. A second-order nonlinear perturbation analysis is employed to investigate the evolution of the instability waves that lead to sheet breakup. The sheet breakup length, thickness, and time as well as size of drops formed upon sheet fragmentation are estimated. It is found that the breakup length, breakup time, and drop size decrease as the Weber number is increased. The breakup thickness increases by raising the Weber number. An initial disturbance of larger amplitude induces faster sheet atomization and larger drops. A higher gas-to-liquid density ratio causes a shorter sheet breakup (intact) length and reduced resultant drop size associated with larger dominant wave numbers. The present theoretical predictions are compared to experimental data, and empirical correlations and favorable agreement is observed.
MHD Combined Convection Flow Past a Stretching Surface
244-257
Swati
Mukhopadhyay
Department of Mathematics, The University of Burdwan, India
Gorachand C.
Layek
Department of Mathematics, University of Burdwan Burdwan, West Bengal, India
Rama Subba Reddy
Gorla
Department of Mechanical Engineering, Cleveland State University, Cleveland, OH, 44115 USA; Department of Mechanical Engineering, University of Akron, Akron, Ohio 44325, USA; Department of Mechanical & Civil Engineering, Purdue University Northwest, Westville, IN 46391, USA
A boundary layer analysis has been presented for combined convection flow of an electrically conducting liquid due to a porous vertical stretching plate with a power law stretching velocity in the presence of a transverse magnetic field. The symmetry groups for this problem are obtained by using a special form of Lie group transformations, namely, a scaling group of transformations. The equations are then solved numerically. It is found that the skin friction decreases and heat transfer rate increases due to the suction parameter. With the increase of magnetic field intensity, the fluid velocity decreases, but the temperature increases. In the absence of magnetic field intensity and suction, the streamwise velocity displays a velocity maximum within the boundary layer when the stretching velocity power law exponent is negative. Effects of the Prandtl number on the momentum boundary layer and on the thermal boundary layer are studied and displayed graphically.
Effect of a Short Roughness Strip on the Near Wall Reynolds Stress Anisotropy Tensor in a Turbulent Boundary Layer
258-266
M. O.
Oyewola
Department of Mechanical Engineering University of Ibadan Ibadan, Nigeria
Hot-wire measurements have been carried out in a turbulent boundary layer subjected to an impulse in form of a short roughness strip with a view to examine it effect on the near-wall Reynolds stress anisotropy tensor. The result indicates that, relative to smooth wall, the anisotropy of the Reynolds stress tensor is modified downstream of the roughness strip. For example, the anisotropy of the near-wall flow is decreased, and the flow shows a closer tendency towards isotropy than the smooth wall near the wall region. The roughness strip acts in such a way as to change the magnitude of the smooth wall data without necessary altering the wavelength of the variation.
Three-Dimensional Heat and Mass Transfer Flow of a Viscous Fluid with Periodic Suction Velocity
267-286
Harmindar S.
Takhar
Engineering Department, Manchester Metropolitan University, Oxford Rd., Manchester, M15GD, UK
In this paper, three-dimensional unsteady free convection and mass transfer flow of an incompressible, viscous liquid through a porous medium past an infinite vertical porous plate is presented. It is considered that the plate is subjected to a time-dependent periodic suction velocity normal to the plate. Approximate solutions for the velocity, temperature, and concentration fields are obtained by using the series expansion method and considering ε as a reference parameter. Expressions for the skin friction, rate of heat transfer, and mass transfers are also derived. The results obtained are discussed for the cooling and heating cases of the porous plate.