Entropy Generation in Nonisothermal Flows: Influence of Boundary Condition Type and Intensity

Entropy generation rates have been computed and analyzed in a fluid heated and sheared by a flat plate for isothermal and isoflux thermal boundary conditions, with and without fixing the total heat exchange power. To address a large number of situations, the plate/fluid temperature gap is allowed to vary up to large values. Thermal boundary condition type affects all entropy generation rates, their composition, and their sensitivity to key parameters. Fixing the total heat power between the plate and the fluid leads to an optimum value of the total entropy generation rate for an optimal ratio between the plate temperature and the plate versus free stream thermal gap. For isoflux plates this optimum ratio is dependent on the fixed exchanged heat power and on the distance from the leading edge, while the optimal ratio stays constant for isothermal plates.