Amitava Sarkar

Thermosolutal Convection in a Rectangular Concentric Annulus: A Comprehensive Study

This investigation presents numerical treatment of governing equations pertaining to thermosolutal flow within an annulus and an application of a model describing the important physical phenomenon as found in muffle furnace. The inner side of the annulus is exposed to high temperature and high solute concentration while the outer side of the annulus is maintained at low temperature and low solute concentration. Darcy-Brinkman-Forchheimer model is used to study the flow, heat and solute transfer in a non-Darcian saturated porous media. The solution is obtained upon application of control volume integration. Modified MAC method is used for the numerical solution of governing equations. Gradient dependent consistent hybrid upwind scheme of second order (GDCHUSSO) is used for discretization of the convective terms. The parameters such as Rayleigh-Darcy number, Darcy number, buoyancy ratio and width ratio, that govern the flow phenomenon have been identified and their effects are critically examined. The fluid flow pattern in the annular space and the associated heat and mass transfer are conceptualized from the obtained isoconcentration, isotherm and flowline contour maps.

Computational modelling of thermal transport phenomena in continuous casting process based on non-orthogonal control volume approach

An efficient computational simulation scheme based on non-orthogonal control volume discretization and co-ordinate transformation techniques has been developed for solving the thermal transport phenomena, which involves tracking of the interface between solid and liquid phases (solidification front) and evaluation of the temperature profile during continuous casting operation. Conservation equations are reformulated in differential-integral form in terms of the transformed co-ordinates. All the terms arising from the non-orthogonality of the control volume have been retained in the numerical solution methodology, and a front tracking procedure has been formulated based on an iterative solution scheme. The formulation has been applied to solve the thermal transport phenomena in solidification processing of an Al-Mg alloy cylindrical ingot during continuous casting, which also includes axial conduction of heat. Theoretical evaluation of the solidification front and temperature distribution in the ingot are in good agreement with the experimentally measured data

Investigation of forced convective heat transfer enhancement in the presence of an electric field – a finite element analysis

The effect of electro‐convection in a cylindrical flow annulus on heat transfer enhancement has been investigated numerically. Weakly ionized air is considered to be the working fluid throughout this work. The effect of exit boundary condition, considered to be the main hindrance for the numerical solution, has been discussed in detail. The present work shows interesting flow field characteristics, which are in excellent agreement with some other established experiments. The heat transfer enhancement, as reported in this work, appears to be small in view of the low magnitude of the applied voltage but it clearly and surely delineates the trend, i.e. with increase in the strength of the electric field, heat transfer enhances.

Coupled magneto-buoyant convection and radiation in an inclined enclosure

Purpose – The current study aims to address the interaction between participating media radiation with thermo-gravitational convection of an electrically conducting fluid enclosed within a tilted enclosure under an externally imposed time-independent uniform magnetic field. Design/methodology/approach – The differentially heated boundaries of the tilted enclosure are considered to be diffuse, gray and the enclosed fluid is assumed to be absorbing, emitting and isotropically scattering. The Navier-Stokes equations, meant for magneto convection are solved using modified MAC method. Gradient dependent consistent hybrid upwind scheme of second order is used for discretization of the convective terms. Discrete ordinate method, with S8 approximation, is used to model radiative transport equation in the presence of radiatively active medium. Findings – Effect of uniform magnetic field with different magnitudes and orientations of cavity has been numerically simulated. The effect of participating media radiation ...

Coupled phenomenon of opposing mixed convection and radiation in presence of participating medium inside eccentric horizontal cylindrical annulus

In the present investigation, the coupled phenomenon of opposing mixed convection and radiation within differentially-heated eccentric horizontal cylindrical annulus has been numerically simulated. The radiation transfer contributed from the participating medium is obtained by solving the non-linear integro-differential radiative transfer equation using the discrete ordinate method. The participating grey medium is considered to be emitting, absorbing, and isotropically scattering. The walls of the annulus are considered to be opaque, diffuse, and grey. From the present investigation, it is found that substantial changes occur in the isotherms as well as the flow patterns, when the Richardson number is allowed to vary in the range of 0.01–1. The eccentricity of the inner cylinder has been varied adequately to illustrate the effect of same in a focused manner. The influence of radiative parameters on the interaction phenomenon has been delineated through the isotherm and streamline patterns.