Thermal buoyancy in round laminar vertical jets

A perturbation analysis is performed which includes the effect of a small amount of thermal buoyancy on the velocity and temperature fields of a round, laminar, vertical jet. A numerical solution of the resulting perturbation equations shows that the predominant effect of positive thermal buoyancy is to increase the axial velocity component of the jet. The magnitude of the effect is shown to increase for decreasing Prandtl numbers. Other details of buoyancy effects on the flow and temperature fields are presented and discussed. It is expected that buoyancy effects may have a large influence on laminar stability.