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Specifying BC points of unstructured grid in NASTRAN format

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Old   July 31, 2014, 00:20
Default Specifying BC points of unstructured grid in NASTRAN format
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Hi, I'm working on a solver for 2d unstructured grid. I built a grid for NACA0012 using pointwise and exported the data in NASTRAN format.

As you know, I need to set boundary conditions to solve the problem. But I cannot specify BC points(far field, surface) from those points listed.

I tried to export the data in CGNS format (because I can see BC points through a CGNS browser) and tried to match indices with those in NASTRAN format. But they didn't match at all.

What I want to know is;

Is there any option that I can set boundaries to connectors in pointwise? Or is there any way to specify BC points?

waiting for reply.
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Old   July 31, 2014, 08:44
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Chris Sideroff
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As you found out NASTRAN does not include boundary condition information. To get access to boundary condition data you need to use a CAE type (in addition to the grid).

You mentioned CGNS already so that's one I might suggest, particularly since there's an existing IO library that you can interface with. If you want something really simple you might look at the ANSYS Fluent or OpenFOAM formats. You can readily find documentation on-line describing those format.

Lastly, if you want to do something a little more custom you might want to considering writing your own Pointwise CAE plugin. If you're interested you might want to start with David's blog post and then jump to the development documentation.
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Old   July 31, 2014, 10:28
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David Garlisch
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Old   July 31, 2014, 10:43
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Quote:
Originally Posted by nba1942 View Post
What I want to know is;

Is there any option that I can set boundaries to connectors in pointwise? Or is there any way to specify BC points?
If I understand the Q correctly, the answer is yes.

First, you must be sure to set your grid to 2D mode in Pointwise. Use the CAE, Set Dimension, 2D menu. In 2D mode, Pointwise treats the connectors as Boundaries and the domains as blocks (volumes).

Next, select CAE solver using the CAE, Select Solver... menu. The solver you choose must support 2D.

Then, use the CAE, Set Boundary Conditions... and the CAE, Set Volume Conditions... menus to create and apply conditions to the connectors and domains.

To export the grid with BC and VC data, use the File, Export, CAE... menu.

If you cannot find an existing CAE export format that will work for your solver, as Chris said, your best option is to create your own CAE exporter using the Pointwise CAE Plugin SDK.

I will be more than happy to guide you if you go down this path.
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Old   July 31, 2014, 11:31
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Thanks for reply I will try that way.
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Old   July 31, 2014, 11:33
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@dgarlisch So what you mean is that NASTRAN format cannot show the BC points in it and I should use CAE format? I want to use NASTRAN format if I can.
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Old   July 31, 2014, 12:40
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Quote:
Originally Posted by nba1942 View Post
@dgarlisch So what you mean is that NASTRAN format cannot show the BC points in it and I should use CAE format? I want to use NASTRAN format if I can.
Short answer:

Pointwise only exports BC and VC data for the active CAE solver. Pointwise does not have a NASTRAN CAE exporter. However, one of the other CAE solvers may use NASTRAN format for their grid data. I will ask around to see if that is true.


Long answer:

Pointwise has two ways of exporting grid data.
  • File, Export, Grid...
  • File, Export, CAE...

A Grid export can be done at any time no matter which CAE Solver is active. However, since BC and VC types are solver dependent, grid export will not export any BC/VC data. Grid export will only export raw grid data.

A CAE export can only be done for the active solver. Pointwise uses the active solver to configure its behavior such as:
  • Support for 2D/3D grids
  • Supported file formats (binary, ascii, fortran)
  • Supported data byte order (big or little endian)
  • Supported Element types (tri, quad, tet, pyramid, etc)
  • Valid VC and BC types

While Pointwise will remember which pieces of a grid are in which BCs and VCs, changing the active solver will clear out the assigned types.
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Old   July 31, 2014, 12:42
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@dgarlisch I really appreciate for your reply. I will try that way. Thank you
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