Numerical study of laminar pulsating flow in a channel

A numerical study was performed for incompressible laminar pulsating flow in a channel. Comprehensive data on the flow and heat transfer characteristics were obtained in the wide range of two main parameters, i.e. the dimensionless pulsating amplitude, 0<A<0.75, and the dimensionless pulsating frequency 0<M<15.0. The velocity profiles resemble much of the quasi-steady solutions at low pulsating frequency, however, the effects of pulsation are distinct and confined to a narrow zone adjacent to the walls when the frequency is high. The entrance length and the skin friction coefficient of pulsating flow all fluctuate in approximately sinusoidal manner. There are phase lags between these parameters and the inlet velocity, and the phase lags are relevant to the pulsating frequency. The changes in the Nusselt number due to the pulsation are pronounced in the entrance region and minor at far downstream locations, and the effects of pulsation on Nusselt number are almost limited in small entrance region when the frequency is high. The results show that, the physical characteristics of pulsating flow are much dissimilar to the steady throughflow, and should be taken into account when thermal equipment is designed under unsteady flow condition.