Is that physical?

Giovanni

Hi! I am running a very simple open channel case, just a rectangular box, with lateral surfaces BC assumed to be wall, BC of top is Pressure outlet, and bottom's BC is wall. The inlet boundary condition is inlet vent, with velocity normal to boundary fixed (e.g. 2 m/s) and the outlet is pressure outlet, the model being used is VOF and all the boundary condition are setted with the open channel flow feature. The problem is that if I set as initial condition the heigth of the free surface and I set initial velocity field's components to zero, when I run the transient simulation immediately when the flow start I can see a soliton wave generate immediately near the inlet and start to propagate. This appens with coarse grids and also with fine grids, and with different inlet velocities, and the heigth of the wave appears to be proportional to the velocity setted in the inlet, this can be a feature of the solitons, as they velocity is c=sqrt(g*(h+A)), but I have same doubt if it is a physical feature of this scenario or if it is just numerical. So what do You think?