This paper treats the interaction of a buoyancy induced convection flow and a free stream impinging at some angle of incidence on an inclined heated flat plate. It is shown that these mechanisms act to either reinforce or oppose one another. In the opposite case, a critical Grashof number exits above which the stagnation point is located behind the origin whatever the angle of attack. The linear stability of the resulting basic flow to three-dimensional disturbances are then analyzed. By using a proper scaling, it is found that the stability problem is governed by a modified Grashof number and therefore the stability characteristics can be reduced to those occurring in Hiemenz flow over a heated horizontal plate.
On utilise une methode pseudo-spectrale de type Laguerre pour etudier la stabilite lineaire d'un ecoulement de convection mixte au point de stagnation bidimensionel non orthogonal. L'ecoulement de base resulte de la superposition de l'ecoulement classique de Hiemenz et d'un ecoulement de cisaillement induit par la poussee d'Archimede et l'effet d'incidence de l'ecoulement exterieur. Sa structure s'apparente a celle de l'ecoulement observe au point de separation. Une definition appropriee du nombre de Grashof permet de ramener la determination des conditions critiques d'apparition d'instabilites tridimensionnelles a celle des conditions critiques relatives a l'ecoulement de Hiemenz.