Cavity Radiation (closed region in axisymmetric model)

[Nicola_C]

Hello, in abaqus I am trying to model a radiant cavity in a very simple axisymmetric model.
I define the internal sides of the frame as surfaces but when I launch the job it gives me this error:

Error in job Job-4: The sum of 46 viewfactor matrix rows are less than one, indicating an open cavity; however, no ambient temperature has been defined. The facets with small row sums belong to elements identified in element set ErrElemVFSmallSumStep1Inc1. If this is a closed cavity this error may indicate a need to refine your mesh. You may choose to increase the value of VTOL to allow your analysis to run without refining the mesh. However the accuracy of the results may be significantly affected so this is not recommended unless you are sure that VTOL value you set is acceptable for your model.
Error in job Job-4: THE ANALYSIS HAS TERMINATED DUE TO PREVIOUS ERRORS.
Job Job-4: Abaqus/Standard aborted due to errors.
Error in job Job-4: Abaqus/Standard Analysis exited with an error - Please see the message file for possible error messages if the file exists.
Job Job-4 aborted due to errors.

Despite the indicated surface is actually closed and the mesh (made with DCCAX4D elements) is extremely dense.

 

[FEA way]

Try the opposite - reduce the mesh density. Apart from that, define cavity symmetry and run some tests with reduced sizes of this rectangular cavity. And finally, try adjusting VTOL parameter.