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-   -   CFX 4.4 New free surface option (https://www.cfd-online.com/Forums/cfx/18662-cfx-4-4-new-free-surface-option.html)

Michael Rasmussen October 3, 2001 11:06

CFX 4.4 New free surface option
 
Hi

I have some problems vith the free surface option in CFX4.4 when I use Meshbuild to generate the grid. If there is only ONE block its ok.

However:

1) If I connect two blocks they cannot have the same name ( in order to activate the option - the block has to be named : Surface region) hense no more than one block can be made with free surface.

2) It does not seem to work with bodyfitted grid even if the solid surface adjacent to the free surface is vertical.

The reason why I'm at bit confused about this is that when I read about this new feature in CFX-Update the background was a simulation of the waves emmited from a ship hull (the grid is body fitted and not vertical). Is this simulation performed with CFX4.4 ?

Any suggestions ?

Regards

Michael

Herve October 3, 2001 11:24

Re: CFX 4.4 New free surface option
 
Michael,

I guess you are referring to the deformable grid feature in the new CFX-4.4? I have used it to look at the "free-surface" profile of water around a set of obstacles and it has worked fairly well. I'd like to add that the grid I created in Build contained about 28 blocks.

If you have a complex bottom topography you can create multiblocks, e.g. two blocks on top of one another, the bottom one incorporating the bottom topography and the top one with vertical vertices being the 3D block on which the deformation can be applied.

Michael Rasmussen October 4, 2001 08:26

Re: CFX 4.4 New free surface option
 
Herve

Thank you for your response

I found the error(s): Basically some "bugs"/my fault

1) Meshbuild cannot accept two blocks with the same name. And you can only select the whole block when setting the 3DUSER patch with the name SURFACE REGION. (Patch and block gets the same name). This problem is however not relevant as the moving grid ignores the block name anyway and concentrates on the 3DUSER patch. Solution : Dont set the relevant patches within Meshbuild - use the command file.

2) Each block has its own definition on i,j,k direction which is not consistent with the global x,y,z coordinate system. My problem was that the J was pointing down and y was pointing up. Solution: Change the origin location on each block so i,j,k points in the same directions as x,y,z.

Maybe these problems are non-exsisting in build - I'm not that familar with Build.

Thank you - my best regards

Michael

Herve October 5, 2001 13:24

Re: CFX 4.4 New free surface option
 
Michael,

I know it might be an extra effort to learn it, but Build is a lot more user-friendly and allows a lot more set ups I think. In this particular case as well as in the case of periodicity for example, there's no comparison.

Herve


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