Abstract
Fluid flow and heat transfer of natural convection over a horizontal heated two-dimensional plate is investigated by means of DNS. Special attention is focused on development and separation of natural convection boundary layer flow. The Rayleigh and the Prandtl numbers are 108 and 0.71. Stimulating the thermal instability, a spanwise sinusoidal disturbance is added on surface temperature of the plate edge as a boundary condition. A stable pair of counter-rotating longitudinal vortices appears when the spanwise wavelength of the disturbance is in a range of 0.06 ? D ? 0.09. Between the vortices, the flow separates without a definite recirculation bubble downstream. Intensity of circumferential velocity of the vortices takes its maximum just downstream of the separation point and the value is 8% of the natural convection velocity.
