Hello, First I would like to describe what i am doing. Description: There is a pipe closed at bottom and open at top(similar to test tube) with dimensions 0.126 m diameter and 0.5 m height. Inside the pipe there is concrete filled upto 0.124m dia and rest at the internal walls filled with lubricating layer(paste). Now side walls are moved down with a velocity of 0.6679m/s downwards. No dynamic mesh used. It is a static case. Now my problem is, I believe i have implemented everything fine in openFOAM and simulation ran succesfully. After some some i found the amount of lubricant which was initialised at walls is increasing in quantity and occupying entire cylinder. Concrete is not found. Don't know why ? I couldn't attach any case files here. For sharing those Im happy.