Which error?

In works, but I suggest to create a rectangle inside the circle so to have a better and more regular mesh. See attached picture. You should create 5 instead on 1 block.

Franco

Dear Franco,

Thank you for the reply.

I am sorry, I forgot to post the error (Attached).

The first time I drew a pipe (Attached), I created one block without any error. When I used two block to draw the geometry (attached at the first time), I met this kind of error.

The suggestion you offered did do a better job to ceate a finer mesh. But I have one question about the suggestion you have given. How to determine the size of the inside square, since the diameters of the surfaces are not the same.

Thank you in advance.

Best Regards,

Bill

Use this forum it can  help you . Good luck.

http://www.cfd-online.com/Forums/openfoam/

Dear Zoubair,

Thank you for your kind help.

Yes, there are more people using OpneFOAM there.

I figured out how to draw.

Thanks a lot.

Regards,

Bill

Are you trying to create a mesh around or within the shown geometry? Both should be possible using the snappyHexMesh utility and placing the "locationInMesh" outside or inside your geometry give that the red face is flat.

Dear Robert,

I am trying to create a mesh within the shown geometry. I have tried to use Salome to create the geometry and mesh. This problem has been solved. Thanks anyway.

I wonder if you could help me deal another OpenFOAM problem at   https://www.researchgate.net/post/How_to_use_the_dimensionless_N-S_equations_in_OpenFOAM

Thank you in advance.

Best Regards,

Bill