General Mechanical

General Mechanical

Ansys Workbench: Obtaining MISC Results of SURF252 Elements (radiation)

    • Werner Berlin
      Subscriber

      Hello all,

      I have a problem regarding the analysis of heat transfer by radiation.
      In my simple example, a cuboid (60 mm x 60 mm x 10 mm) is to be heated via irradiation in a thermal stationary analysis.
      There are no further thermal boundary conditions.
      For this purpose, a cylinder with a radius of 0.5 mm and a length of 165 mm is placed at a distance of 30 mm in the centre and parallel to the irradiated body.
      The cylinder receives a constant temperature of 1860 K over the entire period. The irradiated cuboid has an initial temperature of 22 °C. Both are initially made of generic structural steel.

      I use Workbench to define the surface of the cylinder and a top surface of the cuboid as surfaces in the radiation exchange. Both have the same envelope number and the envelope type open (since the cylinder can also emit radiation to the surroundings).
      Initially, 1 is specified as the emissivity for both bodies.

      I would now like to obtain the distribution of the incident heat flux density on the irradiated surface of the cuboid.

      After the calculation, it is possible to obtain element-related results.
      For the element type SURF252, which according to the documentation is used for 3D radiation exchange, the desired result should also be available. 
      According to the documentation, this should be possible via the element miscellaneous data, in particular NIMSC 10.

      Unfortunately, in some cases I get the message that the data may not be available, sometimes this message does not appear. In all cases, however, the only result I get is the display with minimum and maximum heat flux density equal to zero and no elements to be shown.

      I would also like to process the data on the surface in tabular form (element coordinates [e.g. of the centre node] and corresponding heat flux density).
      For this purpose, I have already tried to access the data using APDL. Unfortunately, in the solver output it is only pointed out that the data is not available and the ETABLE command is therefore ignored.

      I have already used the commands OUTRES,ALL,ALL for the calculation with APDL commands and OUTPR,ESOL,ALL without success.

      What am I doing wrong?
      Is it possible that the SURF252 elements are deleted after the calculation is completed?
      It is my understanding that these are added as an additional layer over SOLID elements to calculate thermal loads due to convection and radiation. 

      Is it therefore also possible that when these elements are added, but I try to access the elements via the selection of a component, that I do not actually select the SURF252 elements, but the underlying SOLID elements, which cannot provide the corresponding data, which is why the ETABLE command is not processed?

      But how can the SURF252 elements be selected via APDL command?

      I would be very grateful for any help!

      Thank you very much in advance.

      With best regards

      Werner

    • Ashish Khemka
      Ansys Employee
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