Numerical Analysis of Laminar Flow and Heat Transfer for an Abrupt Circular Contraction

Detailed predictions have been made of laminar thermo-fluid entry effects for the important practical case of an abrupt circular contraction. The Computational Fluid Dynamics code CFDS-FLOW3D (now CFX) was used, and special care was taken to achieve accurate data, by attention to issues of algorithm choice and grid fineness. Assuming constant properties, detailed local heat transfer predictions have been obtained, for a range of Prandtl and Reynolds numbers and contraction ratio β. The near-entry heat transfer is consistent with the flow behaviour, and gives a clear understanding of the process involved. Qualitatively the results are comparable with experimental and predictive data available in the literature, where however substantial effects due to property changes with temperature were evidenced. This study confirms the presence of flow separation and recirculation found and inferred by other authors, and investigates the phenomena in considerably more detail.