Dynamic mesh "connectivity Error"??

Catthan · October 29, 2011, 07:22

Dear all,

I'm trying to model a 3D case of 2 Wankel rotors connected by pipes sideways.

I have my dynamic mesh UDFs right and working, non-critical skewness (0.60 in the begining up to .85 max during simulation) and a conservative time step.

At about half of the cycle or towards the end of it my model crashes with a message saying smth like
"cavity along longest edge-mesh connectivity error"

the case I am running at the moment is just air, laminar flow, energy equation off.
I am using a tetrahedral mesh from ICEM (passed all checks) with smoothing and remeshing (local cell & face).

I don't remember seeing such error during dynamic mesh preview..
Maybe some skewness warnings which I dealt with by improving the mesh and dropping the time-step.

I've only seen one unanswered similar post from 2005 so I am guessing I am missing smth very obvious.

I would really appreciate any help.

All the best,

mvee · October 31, 2011, 01:33

Hi Catthan

Can you put some images of your mesh on starting of simulation and before your simulations crashes?

rgds
mvee

Catthan · October 31, 2011, 04:32

Hi mvee, thanks.

I lowered the time step a bit and slightly improved the mesh and it worked.
However it would be good if I got it to run a bit faster.

I haven't saved any pics but I'll try to recreate the problem and post them when I do although I don't believe they would be conclusive.

Anything particular you are thinking of - expecting to see?

All the best,

October 29, 2011, 07:22	Dynamic mesh "connectivity Error"??	#1
Catthan Member Join Date: May 2010 Posts: 57 Rep Power: 15	Dear all, I'm trying to model a 3D case of 2 Wankel rotors connected by pipes sideways. I have my dynamic mesh UDFs right and working, non-critical skewness (0.60 in the begining up to .85 max during simulation) and a conservative time step. At about half of the cycle or towards the end of it my model crashes with a message saying smth like "cavity along longest edge-mesh connectivity error" the case I am running at the moment is just air, laminar flow, energy equation off. I am using a tetrahedral mesh from ICEM (passed all checks) with smoothing and remeshing (local cell & face). I don't remember seeing such error during dynamic mesh preview.. Maybe some skewness warnings which I dealt with by improving the mesh and dropping the time-step. I've only seen one unanswered similar post from 2005 so I am guessing I am missing smth very obvious. I would really appreciate any help. All the best,

October 31, 2011, 01:33	connectivity error	#2
mvee Senior Member Vaze Join Date: Jun 2009 Posts: 172 Rep Power: 16	Hi Catthan Can you put some images of your mesh on starting of simulation and before your simulations crashes? rgds mvee

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October 31, 2011, 04:32		#3
Catthan Member Join Date: May 2010 Posts: 57 Rep Power: 15	Hi mvee, thanks. I lowered the time step a bit and slightly improved the mesh and it worked. However it would be good if I got it to run a bit faster. I haven't saved any pics but I'll try to recreate the problem and post them when I do although I don't believe they would be conclusive. Anything particular you are thinking of - expecting to see? All the best,