NUMERICAL STUDY OF STEADY LAMINAR-FLOW THROUGH TUBES WITH MULTIPLE CONSTRICTIONS USING CURVILINEAR COORDINATES

The flow field through tubes with multiple axisymmetric constrictions in tubes was studied numerically. Two practical problem cases were con sidered and the numerical scheme was developed for both. In the first case there are one, two, three and four constrictions in the tube. The effects of the number of constrictions on wall shear stress, pressure drop, streamline, vorticity and velocity distributions as the flow pa sses through the tube were studied and the development of the periodic ity characteristics was investigated. In the second case there were mu ltiple constrictions in the tube equidistant from each other. For this case the governing equations were reformulated for a module at a suff icient distance downstream from the inlet where the entrance region ef fects could be ignored and flow field is assumed to repeat itself. The flow field solutions were obtained in this region. The governing equa tions were formulated in curvilinear co-ordinates and a finite volume discretization procedure was used to solve the problem. The computatio ns were carried out over a range of Reynolds numbers between 50 to 250 for constrictions with 75 percent area reduction. The method is valid ated by comparing some of the solutions with experimental results.