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This study investigates entropy generation for the unsteady flow of a second-grade fluid over a uniformly heated vertical cylinder. The fluid viscosity is assumed to vary with temperature. The mathematical model of this problem is given by highly time-reliant nonlinear coupled equations and resolved by an efficient unconditionally stable implicit scheme. The time histories of average values of momentum and heat-transport coefficients, entropy-generation and Bejan number, and steady-state flow variables are discussed for several values of non-dimensional parameters arising in the flow equations. The results indicate that entropy-generation parameter and Bejan number increase with rising values of group parameter and Grashof number. The results also show that entropy-generation number declines with increasing viscoelastic parameter. [ABSTRACT FROM AUTHOR]

The present work aims to examine the entropy heat generation analysis for unsteady MHD couple stress fluid flow over a uniformly heated vertical flat plate. The mathematical model of this problem is given by highly time reliant non-linear coupled equations and resolved by an efficient unconditionally stable implicit scheme. The time histories of average values of momentum and heat transport coefficients, entropy and Bejan lines, as well as the steady-state flow variables, discussed for several values of non-dimensional parameters arising in the flow equations. Results specify that time required to attain the time independent flow with respect to the flow field variables get amplified with the augmented values of couple stress parameter. The outcomes also indicate that entropy generation parameter upsurges with rising values of group parameter and Grashof number while the reverse trend is observed for couple stress parameter and magnetic parameter. [ABSTRACT FROM AUTHOR]

This study presents the analysis of entropy generation concept for unsteady magnetohydrodynamics Jeffrey fluid flow over a semi-infinite vertical flat plate. This physical problem is constituted by transient coupled highly nonlinear equations and is evaluated numerically by using an implicit scheme. The average values of wall shear stress and Nusselt number, entropy generation number and Jeffrey fluid-flow variables are analysed for distinct values of physical parameters at both transient and steady states. The results show that the time needed for achieving a steady state pertaining to the temperature and velocity gets augmented with the increased values of Jeffrey fluid parameter. The results also specify that the entropy generation number increases with the increasing values of Jeffrey fluid parameter, group parameter and Grashof number while the opposite trend is seen for the magnetic parameter. [ABSTRACT FROM AUTHOR]

In the present research article, the transient radiative free convective hydromagnetic Casson fluid flow past a vertical cylinder with entropy heat generation is analysed numerically. The mathematical model of this problem is constituted by highly time-dependent non-linear coupled equations and they are resolved by an efficient unconditionally stable implicit scheme. The time histories of average values of momentum and heat transport coefficients, entropy generation and Bejan number, as well as the steady-state flow variables are discussed for several values of non-dimensional parameters arising in the flow equations. The results indicate that entropy generation parameter and Bejan number upsurges with rising values of Casson fluid parameter, viscous dissipation parameter, group parameter and Grashof number, whereas the reverse trend is observed for radiation and magnetic parameters. Also, it is viewed that the variation of entropy and Bejan lines occurs in the proximity of the hot cylindrical wall only. Finally, a comparison between the Casson and Newtonian fluid is made based on the obtained numerical results of the present study and this has important implications in industrial thermal materials processing operations. [ABSTRACT FROM AUTHOR]