Learning Forum

[rglsj]

I'm considering a simple geometry shown in the next picture. This is a room and a rectangular human model is standing in the middle of the room.

[Rob]

Don't use "hex dominant" it's a meshing tool for Mechanical where you're interested in surface deformation. It's really not a good idea in CFD, as you've just shown. Also, on the section plane there's a blue triangle/pyramid; click that to show full cells as it's easier to see what's going on.
In your case, if you go full hex map you'll have a very distorted mesh: look at the jump in cell size above the block on the outer surface. If you use an unstructured mesh you can focus cells on the area of interest and then grow in 3 dimensions away from it. Far field may then be hex for economy: I just poly the lot as I'm usually in a hurry and have a cluster!

[rglsj]

Thanks, Rob. Actually, I'm doing all of this because I'm trying to simulate a thermal plume above a human model in a room. It is a natural convection case and I'm having huge problems in order to achieve a converged steady-state solution. I talked with my colleagues and they suggested making the mesh perfect in order to isolate the problem (they think that I'm using the wrong turbulence models or solver settings). So I tried to make a "perfect" mesh so I can find more easily where my problem is.
But that is another topic, in this forum question I asked about mesh generation so I won't bother anymore with my CFD simulation.

[Rob]

Chances are you won't get a steady solution for natural convection. You also want a finer mesh around the body and into the region with the plume.