[CIG-LONG] Gale Velocity Boundary Condition

[Walter Landry]

Feng Lin <rimbong at gmail.com> wrote:
> Hey everyone,
> 
> I get a problem about the Velocity Boundary condition when I setup my model.
> 
> The model is a 2D box x=2 y=0.5
> and make both the left and right side static
> 
> "staticLeft": "true",
> "staticRight": "true"
> 
> I need this kind of velocity B.C.:
> for the right side of box,
> I want top 0.3 is set as vx=1
> but don't fix the bottom 0.2 in x direction so that they can flow
> out side from the left side.

The short answer is that you can not mix Dirichlet and Neumann
boundaries on a wall.  However, I am a bit confused about your model
setup.  The picture you sent implies hydrostatic pressure will force
flow out of the bottom.  Is that what you want, or do you
want to apply a stress to keep material in?

Also, do you really need to model the bottom layer?  Could you instead
just model the upper layer along with a deforming lower boundary with
stress boundary conditions?  Is there some physical experiment that
you are trying to match?

Cheers,
Walter Landry