SUBSIDENCE FRONTS

Approximate analytical solution of the coupled momentum and heat trans fer equations are obtained, using an integral method, for natural conv ection boundary layers which are produced by a step change of surface temperature. The accuracy of the laminar solution is shown to be good, especially at high Prandtl Number (Pr). The corresponding solutions f or the turbulent fluid yield a model of a boundary layer in which the horizontal flow strengthens downstream and is fed by downward motion f rom above. We call this system, which could possibly simulate the init iation of a sea breeze circulation, a subsidence front. Interesting pr operties of the solution include the control of the boundary-layer dev elopment by the product (PrS), where S is the slope of the boundary la yer, and also the generation of log-linear velocity and temperature pr ofiles by heat flux divergence.