Ship resistance
 

hello,

I am new to the forum.
I am currently using star ccm+. I have been looking for answers in the forum and so far, it has worked very well.
Now I am facing a problem and do not know the cause.
I am analyzing ship resistance, fixed or with trim and sink.

I am using for the mesh, the extruder, but after some iterations I get strange things in the outlet at the free surface, I do not know if it can be called wave reflection or what.

I am running a small model, with proper iteration steps (I think) and time looks ok, from courant.

I thought the extruder would help in the pressure outlet of the box or refining. but after iterations nonsense colours start.

could anybody help with this?

thank you all again

maybe I did not post in the proper subforum or could be that this has been adressed before but I found no topic with this specific problem.
anyone could help?
thank you