TY - JOUR TI - Rayleigh-Bénard convection instability in the presence of temperature variation at the lower wall AU - Jovanović Miloš M AU - Živković Dragan S AU - Nikodijević Jelena D JN - Thermal Science PY - 2012 VL - 16 IS - 12 SP - 281 EP - 294 PT - Article AB - This paper analyzes the two-dimensional viscous fluid flow between two parallel plates, where the lower plate is heated and the upper one is cooled. The temperature difference between the plates is gradually increased during a certain time period, and afterwards it is temporarily constant. The temperature distribution on the lower plate is not constant in x-direction, and there is longitudinal sinusoidal temperature variation imposed on the mean temperature. We investigate the wave number and amplitude influence of this variation on the stability of Rayleigh-Benard convective cells, by direct numerical simulation of 2-D Navier-Stokes and energy equation.