A Numerical Study of Thermal Buoyancy in Axisymmetric Laminar Vertical Jets

Abstract

<p>A numerical study of thermal buoyancy in a laminar axisymmetric jet issuing into similar stagnant receiving media is presented. The boundary layer equations governing steady incompressible laminar flow are solved using a finite difference technique developed by Tomich. The results show the predominant effect of positive thermal buoyancy is to increase axial velocity. This effect increases for increasing Prandtl and Grashof numbers. Comparison between the reported numerical solution and the perturbation solution of Mollendorf and Gerhardt shows the latter solution does not adequately describe buoyant flow. Morton's entrainment formulation, on the other hand, is shown to predict the correct scaling factor relating two buoyant flows.</p>