Discussion Forum

Hello,

I was wondering if someone could help me to find the error in my Comsol setup. I know their is an example with the sloshing tank (which i used) but i still can not get the expected result.

The problem is defined as:
Rectangle geometry filled with fluid at rest where the density and the viscousity are known and an external pressure is applied to the left vertical boundary of the rectangle.

I used the fluid physics with:
A boundary stress node is added on the left vertical boundary with a pressure = P.
An open boundary node is added on the right vertical boundary with pressure = 0.
The horizontal boundaries are walls with no slip.

The intention of this model is to move the fluid (which is initially at rest) to the right (x axis) by pressure in time. The result that i want to expect is to see the fluid move to the right.

To solve this i used the moving mesh.

I allowed a predescribed mesh velocity on the vertical boundaries equal to the velocity of the fluid created by the external pressure.
I used the coordinate system of the boundary system and only allowed a prediscribed y displacement with value u (velocity component, is this also correct?). I also checked the use weak constraints box.

I also allowed a predescribed mesh displacement of the horizontal boundaries with predescribed x and y displacement equal to zero. The use weak constraints checkbox is checked here too.

The error is that the fluid doesn't move in time when solved with a time dependent study but there is clearly a velocity field (shown in the plot).

Thanks in advance

PDH