| The backward-facing step flow with free surface is not only a representative example of complex separated flow, but also a kind of familiar phenomena in many engineering fields. In the thesis, a 2D numerical model for the backward-facing step flow with free surface is developed. In the model, realizable k-ε turbulent model is employed and VOF method is used to deal with the movement of free surface. Study cases of different Reynolds number are chosen to test the performance of the numerical model. Numerical results are compared with data given by PIV experiment and available numerical solutions in terms of velocities profiles, free surface displacement, turbulent intensity, turbulent kinetic energy as well as dissipation rate. Good agreements are obtained. On the base of previous results, further numerical study about start flow on backward-facing step with free surface when Re = 1350 was done. It is found the pressure behind the step varies periodically. The influence of free surface movement and large-scale eddies behind the step to the reattachment length is discussed. And also, the relationship between free surface movement, the distance from the step and the periodic of the pressure is given in the paper.
|
PDF Full Text Request