In which coordinates system is expressed velocity

malaboss · April 12, 2013, 05:39

Hi FOAMers !
I am currently working on a cylinder and trying to optimize the mesh in the domain that contains the cylinder.
I would like to minimize the error due to "mesh alignment". For that, I need to have the velocity on each cell and the coordinates of the center of each cell.
I made my mesh with the blockMesh utility.

In the file U in each temporal folder, I can see that I have the velocity vector expressed in a coordinates system.
My first question is : in which coordinate system is it expressed ? : Is it the local coordinate system of the cell ? Or every cell of each block defined in blockmesh dict has the same coordinate system ?

This is a problem for me since I have some edges which are curved. Then the coordinate system of each cell with rotate from the reference defined for a block in blockMeshDict.

I can give you more details if you need it

mturcios777 · April 12, 2013, 13:19

Velocity is always expressed in the global coordinates system.

malaboss · April 18, 2013, 07:00

Thanks a lot !

April 12, 2013, 05:39	In which coordinates system is expressed velocity	#1
malaboss Member Malik Join Date: Dec 2012 Location: Austin, USA Posts: 53 Rep Power: 14	Hi FOAMers ! I am currently working on a cylinder and trying to optimize the mesh in the domain that contains the cylinder. I would like to minimize the error due to "mesh alignment". For that, I need to have the velocity on each cell and the coordinates of the center of each cell. I made my mesh with the blockMesh utility. In the file U in each temporal folder, I can see that I have the velocity vector expressed in a coordinates system. My first question is : in which coordinate system is it expressed ? : Is it the local coordinate system of the cell ? Or every cell of each block defined in blockmesh dict has the same coordinate system ? This is a problem for me since I have some edges which are curved. Then the coordinate system of each cell with rotate from the reference defined for a block in blockMeshDict. I can give you more details if you need it

April 12, 2013, 13:19		#2
mturcios777 Senior Member Marco A. Turcios Join Date: Mar 2009 Location: Vancouver, BC, Canada Posts: 740 Rep Power: 28	Velocity is always expressed in the global coordinates system. immortality likes this.

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April 18, 2013, 07:00		#3
malaboss Member Malik Join Date: Dec 2012 Location: Austin, USA Posts: 53 Rep Power: 14	Thanks a lot !