Theoretical considerations of transition to turbulance in natural convection near a vertical wall

Hydrodynamic stability analysis of an inviscid wall jet shows that instability is possible above a characteristic disturbance wavelength which is proportional to the jet thickness. This scaling is the basis for an argument that transition occurs when the fluctuating time period of the unstable (inviscid) wall jet is of the same order as the viscous diffusion time normal to the jet. The transition must occur when the jet Reynolds number is of the order of 10². Published observations of transition along a heated vertical wall are reviewed in order to test the validity of the proposed scaling argument. Specifically, numerous observations on buoyant jets near isothermal walls, near constant-heat-flux walls, and in enclosures with vertical isothermal walls are shown to support the validity of the transition mechanism proposed