Face separation on adapted hex meshes
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There is one set up method where the user wants to start from a very rough hex mesh which describes the overall geometry of the problem. Then, adapting is done in selected areas to be able to separate smaller entities, for instance as inlets, than the original mesh was able to resolve. However, neither FLUENT 3.3 or 12.0 allows separation operations on adapted meshes with hanging nodes. A workaround so long was to use FlUNS4 to make the separation and then importing the resulting mesh into Fl6 for computation. As it turned out this method works for Fl6 serial but not in parallel where a `f ` t ` does not have all children pointing back to itself` error may be reported. Even if the solution process can be started an error can occur later on. There are two different workarounds! The non-conformal interface workaround: 1) MARK the region where you want to make en adaption 2) Then make to 'Grid/Separate/Cells...' on the marked region 3) Grid/Modify-zones/Slit-face-zone from above resulting 'interior' face (The interior face becomes now a double sided coupled wall) 4) Grid/Modify-zones/Slit-face-zone AGAIN on one of the two coupled walls from above 5) Assign 'interface' boundary types to the two (now uncoupled) walls. 6) Adapt as often you want BUT always for the ENTIRE region in question. 7) Execute TUI command /Adapt/free-parents All adaption related structures are gone, only the formerly adapted mesh is left. 8) Now face-separation is possible 9) Finally couple together your interfaces. 10) After that one can do additional adaption to get a nice fit between the two cell zones. The polyhedra workaround with tpoly utility: This procedure was tested on a simple hex mesh in Fl6.3 as well as in Fl12 beta. 1) Read the meshfile into a serial Fl6.3 and make all your necessary adaptions. 2) Save your file 3) At command prompt in the current working directory use the following conversion command: `utility tpoly input.cas output.cas` This will remove all hanging nodes and create polyhedral cells for those cells who contained hanging-nodes before. 4) Read the converged case file into the serial Fl6.3 session, make the face-separations and set up the rest of the case. Save! 5) Reload this in a parallel Fl6.3 session and compute! There are two different workarounds! The non-conformal interface workaround: 1) MARK the region where you want to make en adaption 2) Then make to 'Grid/Separate/Cells...' on the marked region 3) Grid/Modify-zones/Slit-face-zone from above resulting 'interior' face (The interior face becomes now a double sided coupled wall) 4) Grid/Modify-zones/Slit-face-zone AGAIN on one of the two coupled walls from above 5) Assign 'interface' boundary types to the two (now uncoupled) walls. 6) Adapt as often you want BUT always for the ENTIRE region in question. 7) Execute TUI command /Adapt/free-parents All adaption related structures are gone, only the formerly adapted mesh is left. 8) Now face-separation is possible 9) Finally couple together your interfaces. 10) After that one can do additional adaption to get a nice fit between the two cell zones. The polyhedra workaround with tpoly utility: This procedure was tested on a simple hex mesh in Fl6.3 as well as in Fl12 beta. 1) Read the meshfile into a serial Fl6.3 and make all your necessary adaptions. 2) Save your file 3) At command prompt in the current working directory use the following conversion command: `utility tpoly input.cas output.cas` This will remove all hanging nodes and create polyhedral cells for those cells who contained hanging-nodes before. 4) Read the converged case file into the serial Fl6.3 session, make the face-separations and set up the rest of the case. Save! 5) Reload this in a parallel Fl6.3 session and compute! |
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