An investigation of heat transfer for a pulsating laminar flow in rectangular channels with a boundary condition of the second kind

A finite difference method was used for modeling heat transfer in a pulsating laminar flow in rectangular channels with different aspect ratios for the wall boundary condition $q_w = \mathrm{const}$. The specific frequency ranges were found where the channel perimeter-averaged and the oscillation period-averaged Nusselt number varies in a different manner depending on the channel length and the channel aspect ratio. The predictions for the first and second type boundary conditions are compared. In both cases, there is a frequency range where the average Nusselt number can increase considerably over its steady-state value.