Heat transfer and wave instability of mixed forced and free convection flow

Mixed convection heat transfer laminar flow over a horizontal flat plate, across a horizontal cylinder, and around a sphere was analyzed for both assisting and opposing flow conditions under two surface heating conditions, the uniform wall temperature and the uniform surface heat flux. For an equivalent buoyancy force effect, heating by uniform surface heat flux provides higher local Nusselt numbers than heating by uniform wall temperature. Isothermal vertical and horizontal flat plates were considered in the study of the linear wave instability of laminar mixed forced and free convective flow. Flow along the vertical flat plate becomes more stable as the buoyancy force increases for assisting flow and becomes less stable as the buoyancy force increases for opposing flow. These trends are reversed for flow over the horizontal flat plate.