An Experiment on the Pulsatile Flow of Bingham Plastic Fluids in a High Reynolds Number Region : Influence of the Pulsatile Amplitude

Abstract

To evaluate the influence of pulsatile amplitude, experiments on pulsatile flow of Bingham plastic fluids are performed under the conditions that the time-averaged Reynolds number of a cycle is greater than the critical Reynolds number in the steady state. On the other hand, calculations based on the quasi-steady approximation are performed. These experimental and calculational results show that the characteristic parameters of the pulsatile flow (Φ_{t, 1} and Φ_{z, 1}) obtained from the experiments become greater than the ones obtained from the quasi-steady approximation in a large-amplitude region. Next, the causes of this difference are investigated, and it is suggested that the acceleration parameter plays an important role in explaining the cause of this difference. Finally, the influence of the Hedstrom number is evaluated, and it is suggested that the change of the turbulent viscosity coefficient due to the acceleration becomes notable with the increase in the Hedstrom number.