Mesh within a mesh

FUDM · March 3, 2015, 12:41

Hi!

Can someone tell me if there are any limitations or special cares when creating a mesh block within another larger, less refined mesh block?

Thanks!

JBurnham · March 21, 2015, 16:12

Best practices:

1) the inside block should have cells that are 1/2 the size of the outside block.

2) The locations of the block edges should be such that all the grid lines match up exactly - this can require some algebra.

3) In the outside block, place 'mesh planes' (user-specified grid lines) to match exactly the boundary edges of the inside block.

4) Boundary conditions don't matter - FLOW-3D will change them to 'inter-block boundary type 9' when the simulation begins.

Not all of the rules above are always possible, but they are good advice. Not keeping the rules means that there will greater interpolation error and diffusion and/or reflection of momentum at the inter-block boundary.

FUDM · March 21, 2015, 18:24

Thank you once again for the help!

March 3, 2015, 12:41	Mesh within a mesh	#1
FUDM New Member Fábio Join Date: Feb 2015 Posts: 14 Rep Power: 11	Hi! Can someone tell me if there are any limitations or special cares when creating a mesh block within another larger, less refined mesh block? Thanks!

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March 21, 2015, 16:12		#2
JBurnham Senior Member Jeff Burnham Join Date: Apr 2010 Posts: 204 Rep Power: 17	Best practices: 1) the inside block should have cells that are 1/2 the size of the outside block. 2) The locations of the block edges should be such that all the grid lines match up exactly - this can require some algebra. 3) In the outside block, place 'mesh planes' (user-specified grid lines) to match exactly the boundary edges of the inside block. 4) Boundary conditions don't matter - FLOW-3D will change them to 'inter-block boundary type 9' when the simulation begins. Not all of the rules above are always possible, but they are good advice. Not keeping the rules means that there will greater interpolation error and diffusion and/or reflection of momentum at the inter-block boundary.

March 21, 2015, 18:24		#3
FUDM New Member Fábio Join Date: Feb 2015 Posts: 14 Rep Power: 11	Thank you once again for the help!