Learning Forum

[flo.schuster]

Hello,

i am trying to set up a 2D case that includes the S2S radiation model. I specified all boudary conditions and am now trying to write the view factor file.

When doing so, the cluster calculation is started ("Creating surface cluster") but the program crashes after 2 minutes due to the following error message:

0: mpt_accept: warning: connection timed out after 120 seconds

999999: mpt_accept: warning: connection timed out after 120 seconds

 

There are multiple radiation surfaces (in the order of 10-20) with a quite high resolution (0.5-1mm cell width) in a roughly 150x200mm geometry. But I excluded all non participating surfaces. The remaining settings can be seen below.

 

What can I change to get it running? The resolution of the radiation model can be low. Only the fluids require high resolution.

Is it possible to increase the value of timeout?

[Essence]

Hello,

What is the minimum and maximum optical thickness of your domain?

[flo.schuster]

Hi,

As i am trying to simulate vacuum i used air at a very low pressure. But essentially the optical thickness is 0 uniformly. However, I thought you don't have to specify it in the S2S model in general.

[Essence]

Apologies in the delay. I just wanted to know the optical thickness for my information.

[flo.schuster]

So is there a way to increase the time the view factor calculation is allowed to take? I assume in larger models, this would have to be neccesary.

[Essence]

In cases with a large number of radiating surfaces, the computational expense can be reduced by grouping the mesh faces on radiating boundaries into surface clusters. Surface clusters are made by starting from a mesh face and adding its neighbors and their neighbors in turn until a specified number of faces per surface cluster are collected. The default value of 1 is suitable for a small problem such as this. For larger more complex problems you can increase this number to reduce the memory requirement for the view factor file. This may also reduce the computational expense, however at the cost of some accuracy.

[flo.schuster]

Thank you for the detailed explanation. I will try increasing the surface cluster again. Maybe it is also a issue with my mesh

[Essence]

Sure.