STUDY OF MIXED CONVECTION BETWEEN 2 HORIZ ONTAL PLANES AT DIFFERENT TEMPERATURES .3.

Using laser-Doppler anemometry, we experimentally show that the instab ility of the rest state in the problem of mixed convection (i.e. free and forced) cannot be favorably compared with the theoretical curve co rresponding to neutral stability, but compares rather well with the co nvective instability curve. Subsequently, we measure the velocity ampl itude in the thermoconvective rolls at different locations in the dire ction of the main flow, and compare with the prediction of an amplitud e equation, describing idealized two-dimensional dynamics.