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-   -   negative cell volume detected (dynamic mesh analysis) (http://www.cfd-online.com/Forums/fluent/95784-negative-cell-volume-detected-dynamic-mesh-analysis.html)

g-wagon January 2, 2012 22:10

negative cell volume detected (dynamic mesh analysis)
 
dear all of FLUENT user
i think i'm facing a problem now with my dynamic mesh analysis simulation, i dont know why but this error come almost in my simulation. did i do something wrong please need your help, here is some crop picture of my simulation...

http://s10.postimage.org/4dr0vyf3d/negative_cell.jpg

BigBen January 3, 2012 19:53

Your moving mesh set up is not well defined.
After a number of iterations, cells get negative volumes=> remeshing due to your moving mesh creates bad cells and Fluent cannot follow the simulation.
Make a preview of the deforming mesh motion if you can or verify where the bad cells are to understand where the moving part of your geometry is creaing bad cells.

g-wagon January 3, 2012 22:49

thanks for the reply bigben, but i'm newbie in moving mesh simulation, would you tell me about how to do that??

BigBen January 4, 2012 19:54

There are 3 differents moving mesh. Which one are you using: Remeshing/deforming/layering?
Give me your email, I may have some pictures showing how to do it.

abdulrauf.abdulrazak May 13, 2012 08:37

negative cell volume detected during mesh motion preview
 
Quote:

Originally Posted by BigBen (Post 337919)
There are 3 differents moving mesh. Which one are you using: Remeshing/deforming/layering?
Give me your email, I may have some pictures showing how to do it.

hi.. I am having the same problem like those other guys above there...can u help me how to solve the problem? i was doing a simulation of compression until expansion stroke in combustion chamber of SI engine

BigBen May 13, 2012 17:10

which deplacement do you have? Which kind of cells do you have?
make a picture of you have and what kind of deplacement you want on it to give me an idea

abdulrauf.abdulrazak May 14, 2012 01:39

Quote:

Originally Posted by BigBen (Post 360847)
which deplacement do you have? Which kind of cells do you have?
make a picture of you have and what kind of deplacement you want on it to give me an idea

for my case, u may refer to http://www.cfd-online.com/Forums/flu...amic-mesh.html

please help me..i am doing this analysis for my undergraduate project
thanks

BigBen May 15, 2012 06:09

Reffering to ur picture, ur mesh is purely hexa/quad, only layering can be applied starting at the botom of the "Piston".
Did you mesh the piston thickness? (just for understanding)

If you want to remesh your volume, you need to mesh it in tetra and not in quad.

So what did you do?
When is the error appearing?

jameil.sk February 20, 2013 09:43

Hey Bigben.......here s my email id...jameil.sk@gmail.com
Can u send me some screen shots of how to make the remeshing,layering and smoothening work??

suguaspire August 23, 2013 05:15

Quote:

Originally Posted by BigBen (Post 337919)
There are 3 differents moving mesh. Which one are you using: Remeshing/deforming/layering?
Give me your email, I may have some pictures showing how to do it.

I'm also get same problem can send that pictures for me also. This is my mail id
suguaspire@gmail.com
Thank you

sanjeetlimbu April 5, 2015 22:15

1 Attachment(s)
I am facing issue of negative volume
i am using 2D planer mode - for compression stroke simulation : so the piston line - boundary move to compless inside fluid using the UDF


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