Browsing by Author "R.R. Yadav"

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Analytical solutions for temporally and spatially dependent solute dispersion of pulse type input concentration in one-dimensional semi-infinite media
(2009) Dilip Kumar Jaiswal; Atul Kumar; Naveen Kumar; R.R. Yadav
A linear advection-diffusion equation with variable coefficients in a one-dimensional semi-infinite medium is solved analytically using a Laplace transformation technique, for two dispersion problems: temporally dependent dispersion along a uniform flow and spatially dependent dispersion along a non-uniform flow. Uniform and varying pulse type input conditions are considered. The variable coefficients in the advection-diffusion equation are reduced into constant coefficients with the help of two transformations which introduce new space and time variables, respectively. It is observed that the temporal dependence of increasing nature causes faster solute transport through the medium than that of decreasing nature. Similarly the effect of inhomogeneity of the medium on the solute transport is studied with the help of a function linearly interpolated in a finite space domain. © 2009 International Association for Hydraulic Engineering and Research, Asia Pacific Division.
Distribution of pulse type uniform input in aquifers in tropical regions
(2005) Naveen Kumar; Vijay Kumar Singh; R.R. Yadav
The present work presents mathematical models for the distribution of solute concentration of uniform input of pulse type along sinusoidally varying unsteady longitudinal velocity through such inhomogeneous aquifers of finite as well as semi-infinite extents whose main source of replenishment is infiltration during rains. A new time variable is introduced by using an expression in old time variable. Numerical solutions of such models are obtained using finite difference approximations. At initial stage the dispersion problem is considered steady one in homogeneous aquifer. Its solution is considered as initial condition for the respective unsteady problems. To achieve minimum time period of computation, the parameters of the problem are non-dimensionalized in terms of the existing variables in cases of semi-infinite and finite aquifers separately. The effects of inhomogeneity in both cases are shown through illustrations.
Magnetohydrodynamic flow of a non-Newtonian fluid past a porous plate
(Kluwer Academic Publishers, 1985) K.R. Choubey; R.R. Yadav
This article studies the laminar flow of an electrically conducting non-Newtonian fluid (Rivlin-Encksen type) past an infinite porous flat plate to a step function change in suction velocity in the presence of a transverse magnetic field. The Laplace transform technique has been employed to solve the basic differential equations. The solutions of the velocity profile and skin-friction are obtained and the effects of the visco-elastic parameter, the magnetic field and the time parameter on the fluid flow have been studied in several tables. © 1985 D. Reidel Publishing Company.