Entropy generation due to flow across the abrupt contraction of pipe joints

The flow experiencing the abrupt contraction suffers from the viscous dissipation due to vast change in flow field across the plane of contraction. In the present study, simulation of flow field and entropy generation rate due to viscous dissipation are carried out for different upstream Reynolds numbers. The flow situation is considered to be isothermal to avoid the influence of heat transfer on the entropy generation rate. A control volume approach is introduced when discretizing the governing equations of flow. In order to secure the grid independent solution the grid independent tests are conducted. It is found that overshooting of axial velocity occurs along the symmetry axis across the plane of contraction. Entropy generation rate enhances with increasing Reynolds numbers. The location of maximum entropy generation rate becomes almost identical for all Reynolds numbers considered in the present study. (C) 2008 Elsevier Ltd. All rights reserved.