Strange behavior of water surface near solid body
 

I am experiencing strange initial behavior of my water surface near a solid body at the beginning of my simulation.

https://i.imgur.com/nOeISOv.jpg

The water level starts out flat from setFields, and I took away the waves that I will eventually be including. Even with calm initial conditions, the water level dips near the solid flap (the flap is hinged at the bottom so that it may rotate).

My boundary conditions on the flap are movingWallVelocity for U, and similar to a normal wall for all others.

I am using rigidBodyMotion solver to generate movement of the flap, and an AMI patch rotates a cylindrical portion of the mesh surrounding the flap. In previous simulations, I used a prescribed motion of the flap (with constant rotational velocity) and did not experience the strange initial water surface behavior.

Hi Justine,

See the link below for instructions on how to include an image in a post:
https://www.cfd-online.com/Forums/si...nt-appear.html

Best Regards,
Paulo

Thanks, I have posted an image. As an update, this water surface issue occurs even when I go back to a prescribed flap motion and set the angular velocity to zero (so indeed there is no flap motion, yet still a disturbance near the flap). I am trying to retrace my steps and determine what is causing this issue. Any help would be greatly appreciated.

Why movingWallVelocity? Seems wrong to me.

I used movingWallVelocity based on a tutorial case that had a floating object or something of that nature (it might have been the propeller case). Like everything I try to do with OpenFOAM, I find examples and work from there.

The flap is a moving solid body and needs to rotate about a "hinge" point, which happens to be the origin in my model.

I have removed the flap entirely and found that the behavior continues. It is likely due to the circular AMI. If I plot velocity, there is definitely something going on around the AMI when it shouldn't be.

checkMesh
 

Additional information: when I run checkMesh, it "Failed 1 mesh checks" but it doesn't say which check it failed. Does it have to do with "***Number of edges not aligned with or perpendicular to non-empty directions: 24057"? Here is a picture of the circular/cylindrical part of the mesh:

https://i.imgur.com/JBoRpvW.png

Could it be it simply needs more refinement, or is something else possible going wrong with the AMI?