Abstract
A numerical study of transient natural convection in a square cavity with partly thermally active side walls is introduced. The thermally active regions of the side walls are periodic in time. Top and bottom of the cavity are adiabatic. Nine different positions of the thermally active zones are considered. The governing equations are solved using control volume method with power-law scheme. The results are obtained for various values of amplitude, period, and Grashof numbers ranging from 104–106 and different thermally active situations. It is found that the average heat transfer increases by increasing amplitude for P=1,5, and decreasing for P=3. The average Nusselt number behaves nonlinearly as a function of period.