Pointwise Pointers: O-Grid Tutorial

[@gregliako7995]

Dear Travis, If there should be a Mesh-Hero, then you should be the man for that!

[@TravisCarrigan]

Thank you!

[@uchennaogunka]

Hello Travis, thank you for the video. Please, I am trying to generate an Ogrid with NACA0018 using Ansys ICEM. Would the airfoil generator script file work with ICEM?

[@aarjavmalhotra]

Hi ! Your tutorials are extremely helpful. I tried generating an O grid with NACA2412 for fluent, for which I just selected 2D ANSYS Fluent and defined the boundary conditions after the extrusion and exported the mesh. However, fluent throws up a warning that non positive volumes exist. Can you please tell me what's going on over here ?

[@CadenceCFD]

Yes, you need to reorient your mesh in Pointwise using the Edit, Orient command. Fluent expects right-handed domains and blocks.

[@karimsayed4889]

when I run the meshing script, I get an error " can't read "crvlength" no such variable"

[@oscar99999]

Travis, Thank you for your excellent tutorials. I have a problem however, which is that when I export CAE from pointwise I only get 5 files (boundary, faces, neighbour, owner and points) whereas in your repository you have the additional files "cellZones, pointZones, and faceZones". I am finding that these are required to run a simpleFoam simulation. I run the exact same case in OF but the only difference is I use the exported files from the pointwise project instead of the ones you provided directly in the case folder. Where did you get those extra files from? Many thanks, Oscar

[@TravisCarrigan]

+Oscar Wilsby In the latest version of Pointwise you can choose to export sets and zones. However, you do not need them for a simpleFoam calculation.

[@oscar99999]

+Travis Carrigan It's very strange indeed. I am seeing the following: When I use the polyMesh files you have attached in your GitHub repo there is no problem running simpleFoam. However when I open the pointwise file for this case and I export the 5 required files by Export->CAE and use that input in my polyMesh then OF complains by throwing a Floating point exception.The simulation residuals are also in the 1000s. Examining the files I can now see a difference: 1) The files automatically outputted from PW do not have the standard OF comment header but this shouldn't make a difference 2) the 'boundary' file does NOT contain the 'inGroups' entry in when I export from PW, whereas yours does. I changed this but it didn't change my OF error. 3) The entries in the remaining files are not identical. For example in 'faces' yours starts with 24341 ( 4(200 6422 6161 99) and when I export your PW project I get a file that starts with 24341 ( 4(621 6422 265 104) Maybe this is not an issue but I honestly am running out of ideas to try. Many thanks for your help.

[@TravisCarrigan]

+Oscar Wilsby Ah, I know what's going on. You need to first ensure that the grid is scaled correctly...which it should be. Second, and most importantly, you need to run 'renumberMesh -overwrite' to renumber the grid. Pointwise does not export points and cell in any particular order and OpenFOAM is very sensitive to the grid bandwidth. By running renumberMesh you are basically reorganizing the grid to reduce the bandwidth of the matrix. That should help.

[@oscar99999]

Yes! It really was that simple. Thank you, you have been a huge help.

[@oscar99999]

Travis, On a possibly related issue, have you ever run into OF throwing an error that "face X does not match neighbour by Y%"? I am trying to run a simulation of a airfoil cascade passage and the error is of the order of 0.8%. Surely PW would have matched the mesh faces to a higher precision? I made sure that the database entries constituting the top and bottom of my passage in my project where marked as periodic, and so I assumed PW would ensure they match. I have seen people recommend that you export the periodic faces patch BC in PW and then use a createPatchDict to get the cyclic BC, but that hasn't been of use to me. Is there any chance I need to make a simple correction in PW to ensure my cyclics are matching? EDIT: In fact I can see that my cyclic boundaries have been mirrored - by that I mean for my upper periodic boundary the first location as you move axially forward actually corresponds to the last location in the axial direction of the lower periodic boundary. Thanks!

[@CadenceCFD]

+Oscar Wilsby Pointwise does not guarantee the order of periodic faces. OpenFOAM requires that the faces be ordered identically on the periodic patches. You'll need to use the createPatchDict to get the cyclics working correctly.

[@mikestar8324]

Thank you for your informative tutorial. Is this software (pointwise) free?

[@mikestar6143]

Hi...thanks for the great video. I am trying to run the openfoam case and I am getting the following error : --> FOAM FATAL IO ERROR: keyword origin is undefined in dictionary "/home/OpenFOAM/OpenFOAM-NACA2412-master_copy/system/controlDict.functions.forces" file: /home/OpenFOAM/OpenFOAM-NACA2412-master_copy/system/controlDict.functions.forces from line 11 to line 27. From function dictionary::lookupEntry(const word&, bool, bool) const in file db/dictionary/dictionary.C at line 442. FOAM exiting I should mention that I have used "renumberMesh -overwrite" before runing the case. Could you please help me with this problem?

[@astafzciba]

there is millions of tutorials about pointwise all of them about airfoils

[@RiemannsBeard]

Hey Travis, thank you for such a good tutorial. I'm able of meshing a NACA0012 following your movie but I would like to control the radial resolution. I tried to modify the radial nodes number after meshing but the hyperbolic feature disappeared... Is there any way to do that?

[@TravisCarrigan]

Great question. You'll need to re-extrude. Simply select the domain and go to Grid, Re-extrude.

[@RiemannsBeard]

Hi again Travis! Thanks for your reply! Itried to do that but I'm afraid that after changing the default number of radial nodes, the Re-extrude tool is not available. Can you detail it step by step after de first default extrusion? Thanks!

[@TravisCarrigan]

Correct, you cannot change any of the dimensions after the extrusion (or modify the grid in any way) or re-extrude will no longer be available. You will need to delete the domain and recreate the extrusion.

[@RiemannsBeard]

Travis Carrigan So how to extrude an O-grid for the airfoil with the trailing edge connector prescribing the number of radial nodes? That's my big question

[@prat2309]

Hello Travis.....I was wondering if you would change anything in this method if you were building a mesh for the NACA 0009 airfoil...For some reason, for angles beyond 8 degrees, the solution for NACA 0009 at Re 500,000 does not converge.

[@TravisCarrigan]

As long as you have a blunt trailing edge and performed a hyperbolic extrusion, the grid quality should be of sufficient quality. Now if I recall correctly, the NACA 0009, being a thinner profile, will stall sooner than the NACA 2412. Therefore, the flow is probably largely unsteady and it can be really challenging to get a converged result at those high angles of attack.

[@prat2309]

Travis Carrigan Thanks for your reply. I understand convergence would be a problem at angles close to stall. However, the solutions converge well in the case of very high angles of attack such as 30-60 degrees. Any suggestions? It is funny because solution fails to converge only for angles between 10-20 degrees AOA.

[@haveanicetime]

I wanna the program please.

[@madansridhar924]

Can u dor for three element airfoil

[@hedleyfurio]

good and informative - thanks

[@TravisCarrigan]

Hello Hedley! I'm happy you enjoyed the video and found it informative. Thank you.

[@ParisiGio]

thank you!

[@jigsaw6627]

can u do the same tutorial but using ANSYS