Sliding BC in ALE framework

[Luciano Garelli]

Hello,

I was solving a problem with a deformable mesh and everything i it's ok with fixed boundaries but when I set sliding boundary for the mobile mesh (ialtyb(ifac) = igliss) the behavior is not what I expected when wall BC is used in the fluid.

In the documentation is mention that "ialtyb(ifac) = igliss: The mesh slides on corresponding face ifac. The normal component of mesh velocity is automatically set to 0. A homogeneous Neumann condition is automatically prescribed for the other components, as it's the case for 'Symmetry' fluid condition."

I shared the results of a simple test problem. It is a cylinder with an imposed movement in the x and y directions with a wall BC for the fluid. If I set a symmetry conditions for the fluid on all the sides of the box and a sliding conditions for the mobile mesh the vertex slide a no normal mesh velocity appears. But, if I set a wall condition for the fluid on all the sides of the box I get a rigid movement of the domain. I can't understand this change in the behavior when the fluid BC's are changed.

Link to a video with the test case
https://drive.google.com/open?id=1m2-mA ... LPsAsFotOc

Regards,

Luciano