G. Nath

Non-darcy natural convection from a heated vertical plate in saturated porous media with mass transfer

Abstract The nonsimilar and self-similar flows for the steady natural convection over a vertical heated surface in a saturated porous medium with mass transfer using non-Darcy model have been studied under boundary layer approximations. The differential equations governing both the nonsimilar and self-similar flows have been solved numerically using an implicit finite-difference scheme developed by Keller. The results indicate that both heat transfer and velocity field are appreciably affected by the modified Grashof number and mass transfer except that the effect of the modified Grashof number on the heat transfer for large suction is very small. It is found that the maximum velocity occurs at the wall and it increases as the modified Grashof number or injection increases.

Finite-difference and improved perturbation solutions for free convection on a vertical cylinder embedded in a saturated porous medium

Presentation de calculs par la methode des differences finies et par la methode des perturbations de la couche limite de convection naturelle le long dun cylindre vertical mince et isotherme noye dans un milieu poreux sature

Heat and mass transfer in unsteady compressible axisymmetric stagnation point boundary layer flow over a rotating body

The study deals with the unsteady laminar compressible stagnation-point boundary layer flow over a rotating body of revolution (sphere) with mass transfer when the free-stream velocity, the rotation of the body, the surface mass transfer, and the wall temperature vary arbitrarily with time. The rotation of a body is found to exert a strong influence on the skin friction, but its effect on the heat transfer is comparatively weak. On the other hand, the effect of the variation of the wall temperature with time on the heat transfer is appreciable; the skin friction, however, is affected only slightly by it. The variation of the density-viscosity product across the boundary layer has a strong effect on both the skin friction and the heat transfer. Suction serves to increase the skin friction and heat transfer, but injection does the reverse. A velocity overshoot is found in the longitudinal velocity profiles which increases as the rotation of the body increases.

Unsteady, swirling boundary-layer flow with heat and mass transfer in nozzles, diffusers and hydrocyclones

The unsteady, laminar, incompressible, swirling boundary-layer flow with heat and mass transfer in a nozzle, a diffuser and a hydrocyclone has been investigated when the free-stream velocity and mass transfer vary with time. The governing non-linear partial differential equations with three independent variables have been solved numerically using an implicit finite-difference scheme. Both the heat transfer and skin friction are found to be strongly affected by swirl and mass transfer, but only moderately affected by the free-stream velocity. However, the Prandtl number strongly affects only the heat transfer, whereas the skin friction is unaffected by it.

Compressible boundary-layer flow at a three-dimensional stagnation point with massive blowing

Abstract The effect of massive blowing rates on the steady laminar compressible boundary-layer flow with variable gas properties at a 3-dim. stagnation point (which includes both nodal and saddle points of attachment) has been studied. The equations governing the flow have been solved numerically using an implicit finite-difference scheme in combination with the quasilinearization technique for nodal points of attachment but employing a parametric differentiation technique instead of quasilinearization for saddle points of attachment. It is found that the effect of massive blowing rates is to move the viscous layer away from the surface. The effect of the variation of the density- viscosity product across the boundary layer is found to be negligible for massive blowing rates but significant for moderate blowing rates. The velocity profiles in the transverse direction for saddle points of attachment in the presence of massive blowing show both the reverse flow as well as velocity overshoot.

Magnetic hypersonic rarefied flow at the stagnation point of a blunt body with slip and mass transfer

The hypersonic viscous flow of a slightly rarefied electrically conducting gas with variable properties in the stagnation region of a blunt body with an applied magnetic field, slip and mass transfer (suction or injection) has been studied. The similarity solutions of the boundary-layer equations have been obtained numerically using the method of quasilinearization. The results indicate the extent to which the magnetic field, slip and mass-transfer parameters etc. affect the heat-transfer rate.

Film condensation along a frustum of a cone in a porous medium

Analyse mathematique du transfert de chaleur au cours de la condensation pelliculaire sur un tronc de cone noye dans un milieu poreux rempli dune vapeur deau saturee seche. Etude de linfluence du sous-refroidissement de la paroi

Flow and heat transfer in steady laminar compressible boundary layer swirling flow in a nozzle

The axisymmetric steady laminar compressible boundary layer swirling flow of a gas with variable properties in a nozzle has been investigated. The partial differential equations governing the non-similar flow have been transformed into new co-ordinates having finite ranges by means of a transformation which maps an infinite range into a finite one. The resulting equations have been solved numerically using an implicit finite-difference scheme. The computations have been carried out for compressible swirling flow through a convergent conical nozzle. The results indicate that the swirl exerts a strong influence on the longitudinal skin friction, but its effect on the tangential skin friction and heat transfer is comparatively small. The effect of the variation of the density-viscosity product across the boundary layer is appreciable only at low-wall temperature. The results are in good agreement with those of the local-similarity method for small values of the longitudinal distance.

Unsteady nonsimilar natural convection over a vertical flat plate in a thermally stratified fluid

Etude de la couche limite de convection libre laminaire incompressible non stationnaire pour un ecoulement non similaire au-dessus dune plaque plate verticale dans un milieu stratifie lorsque la temperature de la paroi varie dans le temps

Forced convection heat transfer from a flat plate with an unheated starting length

Analyse mathematique du transfert de chaleur par convection forcee dune plaque plane presentant une longueur initiale non chauffee. Etude numerique de linfluence de la valeur du nombre de Reynolds sur la portion non chauffee