Extracting geometry information from Plot3D File Format
 

Hello all,

I am currently attempting some preliminary studies on flow separation, vorticity and turbulence modelling. I have managed to find a well-known and widely studied geometry and modelling benchmark for 2D separated flows, using an asymmetric diffuser as described in the link below -

http://www.grc.nasa.gov/WWW/wind/val...2/buice02.html

This is my first time using the Plot3D format (failed attachment) and I opened the mesh in ICEM. The problem is that the perimeter of the geometry is a singular object and once I convert to .msh and progress with Fluent I am unable to set boundary conditions appropriately. I just need some assistance in creating a separate line geometry which can be used to define an inlet and outlet and then analysed in Fluent.

Please provide some guidance and suggest a suitable approach for this objective.

Thanks,

In ICEM CFD you can create new part (right click on parts) and assign entities (geometry and/or mesh) to those parts. During export to fluent, Parts become boundary conditions.

Best regards,

Simon

Thanks for your response Simon.
I have noticed that the entire outer perimeter including the inlet, outlet, upper and the lower walls are a single entity in the model tree. This is the main problem since I would like to select the each of these sides as a separate Fluent boundary.

Is there a way to split the line and convert this into a part and then assign the boundary conditions upon transfer into Fluent, as you suggested earlier?

I am very inexperienced with ICEM however, I would really like to extract this geometry and simulate the resulting flow separation. I remember modifying it so that the inlet and outlet 'lines' were deleted from the ICEM model and when I transferred this into Fluent I just received error messages due to 'open' geometry.

I look forward to your suggestions.

Yes, you can select any entity to assign to the new part.

So, right click on parts => Create New Part and name it "INLET". Select the entity you want (such as the curve that represents your inlet) and apply.

When you generate the mesh, the new line elements generated along that line will be in the "INLET" part.

DO NOT delete the part or those lines. Fluent needs them as boundaries.

When you get to Fluent, they will be available as a boundary condition or Zone.

I have finally found the time to try this out and now I can't even import the mesh file into ICEM anymore. This is so frustrating now since I am following the exact directions given on the research website. Since I am unable to open this or attach the Plot3D file I will share the link with you and hopefully you can provide some guidance.

http://www.grc.nasa.gov/WWW/wind/val...1/buice01.html

The .xyz format should be imported into ICEM as an unstructured, 3D, single block, whole mesh if I am not mistaken however I am confused by the 'convert to unstruct' option. I have been trying for a long time with various settings and I just can't get it to work.

Thanks for your input thus far.

Was anyone able to extract the geometry or import the file into ICEM and Fluent?

Thanks for any suggestions you may have.

Tried Another Grid from a Similar source and this was a single block, 2D, structured, double-precision import however, I keep getting the warning message shown below. ICEM simply doesn't load or make any further progress after this.

Running ICEM CFD/CAE PLOT3D Input Interface Vers. 14.0.0
---------------------------
Plot3D file contains 1 block(s)
Nodal dimension of block(s):
- Block #1: 1 x 2 x 1409
Skipping block #1 with iblank value 0
--------------------------------------

I would really appreciate it if someone is able to interpret this and explain what could possibly be going wrong. The link for the File is given - http://turbmodels.larc.nasa.gov/bump_grids.html And I used the 2D Plot3D file formats.

Thanks,

I finally managed to work with the Plot3D files, but the process used to obtain the mesh might have been mostly non-standard.

Firstly, I had to open Fluent standalone application and then import the Plot3D file. This was immediately saved as a Fluent CASE File and led to it's successful transfer into ICEM.

Afterwards, I realised that all the techniques Simon mentioned above, regarding the creation of geometry and boundary conditions worked flawlessly. I was just hoping that I wouldn't have to use this tedious, non-standard process to open every single Plot3D file I encounter and that ICEM would simply be able to import them directly.

Thanks everyone for your ideas and suggestions.