Dear Friends !

I would really need Your help. I am currently simulating the temporal development of an interface between liquid and gas, by using Comsol Multiphysics.

The problem can be simplified in terms of a rotating central liquid pick up (a small rotating cylinder endowed with an internal Archimedean screw), which rotates inside a bigger vertical cylinder. 30% of this cylinder is full of liquid, the upper part is full of gas.

I have tried to solve the problem in this term:

1. Two phase flow, laminar, level set (chns) + Moving Mesh (ALE).

2. BOUNDARY CONDITIONS for Two phase Flow Laminar level Set:

For internal rotating walls : no_slip_CW

For the External walls of the shell: No slip

For the interface: Initial interface

Stabilisation method: (GLS)

3. Subdomain SETTING for the moving mesh:

FREE DISPLACEMENT

BOUNDARY CONDITIONS TO PREDICT THE ROTATION OF THE MESH:

ROTATE CW: Internal rotating Structure;

FIXED: External Shell

THIS IS THE ERROR I GOT:

Error: 7300
Pointwise constraints for time-derivatives are not supported.

Can somebody help me ?

Thank You, in advance !
Christiano