I'm trying to generate a 3D grid around a hydrofoil. It generate all surface mesh but when I try to generate the mesh on the volume it says that a logical cube cannot be found. What is the that logical cube and how can I fix that error?????

Hi there,

You are trying to mesh with Hex elements. For using hex elements in gambit you need to have a cube. Each surface should exactly map with the surface on the opposite side.

Use tet elements. this should fix your problem.

trying to mesh using Hex elements in gambit is complete waste of time unless the geometry is simple.

Cheers

Dan

a non logical cube is this. Imagine a small circular face that sits inside a large circular face and subtract one from the other to be left with an annular face. This is a non logical cube and gambit cannot mesh it as it is a face made up of 2 edges that don't meet. Splitting the face across into 2 faces of 4 edges each means they are then logical cubes and each can be map meshed.

Thank you. I don't want to generate unstructured grid (for these gambit has no problem), but I want to use quad and hexa cells. There is another code who can generate grids, and can be imported in fluent??

you can use gambit. just decompose the geometry so it is mappable for hexa.

you can use gambit. just decompose the geometry so it is mappable for hexa.

I did that. I split the domain in 4 volumes-1 upstream, 1 left , 1 right of the strut and 1 in downstream). The problem is I have 4 faces (2-left and 2-right)inside the domain. When I set the boundary condition I do not consider these 4 faces, but the fluent code considere them some kind of wall, because I obtain wrong results. If I eliminate these faces by uniting the volumes , gambit give me that error with logical cube.

Did you define 4 volumes (continuum) in Gambit? You should define only one, selecting your 4 volumes as "Entity".

Yes, I defined all volumes as 1 fluid entity; my problem is with geometric 4 volumes.