Projecting points to surface
 

I want to read in a .stl file and use it to define a surface. Then given an x,y location, I'd like to project onto the surface to find the z height. Can anyone help with how to do that. The surfaceDisplacement boundary condition that can be used for the "pointMotion" field with the moveDynamicMesh solver seems to be able to do this, but I can't figure out how to do that. I've taken the "transformPoints" utility and modified it to take a block mesh made with "blockMesh" and translate points vertically to conform to an analytical surface definition at the bottom, but now I want to have the ability to conform to a general surface definition that comes in the form of an .stl file.

Thank you,

Matt

Use blockMesh and define a mesh of let say 1m thick and 1000m above your stl surface. You can chose whatever thickness and distance above your stl, it doesn't matter.

Then, use moveMesh to project the bottom boundary of your mesh on the stl surface. You'll get elongated cells, and the bottom boundary will be a projection of the initial mesh onto the stl surface. The displacement of your mesh is controlled via the pointDisplacement file.