@article { author = {}, title = {COMPARISON BETWEEN TWO METHODS FOR ENHANCING HEAT TRANSFER IN SEPARATED CONVECTION FLOWS-SECOND LAW ANALYSIS}, journal = {Iranian Journal of Science and Technology Transactions of Mechanical Engineering}, volume = {38}, number = {M1}, pages = {9-23}, year = {2014}, publisher = {Shiraz University}, issn = {2228-6187}, eissn = {}, doi = {10.22099/ijstm.2014.1923}, abstract = {In the present work, a laminar forced convection flow over a backward-facing step(BFS) in a duct is investigated. This study concerns the practical application of entropy generationanalysis in separated convective flow for the first time. Two different methods, (i) attaching abaffle to the channel top wall and (ii) employing suction for enhancing heat transfer performance,are compared by the second law criteria. Entropy generation in the flow domain which indicatesthe amount of irreversibilities in convective flow is computed numerically. Heat transfer andviscous dissipation are the two sources of entropy generation in convective flow. The set ofgoverning equations defining conservations of mass, momentum and energy are solvednumerically to calculate velocity and temperature profiles which are needed for estimating entropygeneration. The SIMPLE algorithm is used to resolve the pressure-velocity coupling. Numericalexpressions, in terms of entropy generation number (Ns) and Nusselt number (Nu) are derived indimensionless forms. The total entropy generation is also calculated in different case studies forcomparing the amount of irreversibilities. Numerical results revealed that using baffles andpermeable walls with suction have considerable effects in enhancing heat transfer but the presenceof baffle produces more irreversibilities than the suction technique.}, keywords = {Entropy generation,suction,baffle,backward facing step,forced convection,irreversibility}, url = {https://ijstm.shirazu.ac.ir/article_1923.html}, eprint = {https://ijstm.shirazu.ac.ir/article_1923_8eb489971eab3fa155505c65a9e1eedf.pdf} }