| This thesis entitled "Studies of Some Free Convective Heat and Mass Transfer Problems of Incompressible Fluid With or Without Thermal Stratification" deals with a few problems on free convective heat transfer with thermal stratification. and also heat and mass transfer without thermal stratification. It comprises of fifteen chapters. The first chapter is an introductory one which deals with the development of the subject and the second chapter is on the review of relevant literature.;Chapters 3 to 12 deal with the problems of thermally stratified fluids in which pressure work and the vertical temperature advection terms are considered in the thermodynamic energy equation (which are generally not considered in the conventional models of similar problems). Since the vertical temperature advection terms and the pressure work term are similar in nature so they are combined into a single term, (termed as stratification parameter). Due to the introduction of this term in the energy equation, both the momentum equation and the energy equations become coupled. As a result exact solutions to this type of problems involve some difficulty because of the coupling. Since we are interested in obtaining the exact solutions of the problems, so to tackle this situation we are restricted to a fluid whose thermal expansion coefficient is that of a perfect fluid with Prandtl number unity only. Further, in order to delay or prevent flow instability, we restrict our attention to linearly varying ambient temperature Tinfinity and also approximate rhoinfinity/rho as unity. Introduction of this stratification parameter in the energy equation justifies a universal phenomenon that warm fluid riscs, expands and cools relative to the environment whereas cool fluid subsides, compresses and warms relative to the environment. We compare our stratified solutions with the unstratified solutions and found significant differences over the conventional results. Also, due to the introduction of stratification parameter, unsteady solution comes out as steady at larger times, whereas in case of unstratified fluid it grows continuously with time.;The rest of the three chapters (13 to 15) deal with combined heat and mass transfer effects (without thermal stratifications). In some cases porous medium, MHD, chemical reaction and radiation are also considered in both stratified and unstratified fluids. |
