topic Re: Nodal values do not match CFD results in CFD Forum

Nodal values do not match CFD results

dshom — Wed, 23 Nov 2022 05:10:39 GMT

Hi, I am trying to simulate a room's ventilation and transfer the analyzed result into virtual reality. For this, I am using the feature of exporting nodal results. In the CFD results, I have identified a point and encircled the coordinates in red in the screenshot in the below folder. I tried looking up the csv file for the coordinates but unfortunately did not find them.

Could someone help me in understanding how to accurately get all the location of the points and their associated parameters?

Folder with the files : CFD Forum

Thanks,

Debayan Shom.

Re: Nodal values do not match CFD results

karol.suchon — Wed, 23 Nov 2022 10:04:02 GMT

Hello.

The value of the points in the GUI is taken from an approximated value between nodal values.

You have a Nodal value which is the value of the parameters in the mesh nodes and the software approximates the value between these points.

That's why you could not find the the value in CSV file, the point circled in red is not the nodes.

To get the value in the points which are not from the mesh, use the Points option.

Karol

Re: Nodal values do not match CFD results

dshom — Wed, 23 Nov 2022 10:58:55 GMT

Thank you for the reply Karol.

I tried to implement that and realized that every individual point needs to be specified manually as shown in the screenshot below:

Is there a way to define the points in an automated manner?

Regards,

Debayan Shom.

Re: Nodal values do not match CFD results

karol.suchon — Wed, 23 Nov 2022 11:05:25 GMT

If they are on the common plane you could use an XY plot to get the value.

There is an option to use to read the coordinates from the file.

But I do not understand what you want to achieve, so if you could tell me why you need the values in specific points?

So maybe is there a much simpler way.

Re: Nodal values do not match CFD results

dshom — Wed, 23 Nov 2022 11:11:52 GMT

I wanted to translate each value obtained in the results in a (x,y,z) coordinates format. For eg. (0,0,0) would have temperature=75 F and velocity=60 ft/min, (0,0,1) would have temperature=73 F and velocity=59 ft/min, (0,0,2) would have temperature=74 F and velocity=61 ft/min and so on. If I am able to find out each point of the room in the CFD result and have an equivalent point system in a CSV format, then I would be able to translate these results in virtual reality to analyze them.

Re: Nodal values do not match CFD results

karol.suchon — Wed, 23 Nov 2022 11:59:58 GMT

Ok, I understand the idea. So you need the value in the constant-size hexagonal mesh.

Probably the planes with a constant distance between them and Xy plot or with the save table option will be helpful.

But I will really try to find the possibility to read the entire nodal dataset if that is possible.

If we read the points with too corase distance it will look weird in the VR.

Re: Nodal values do not match CFD results

dshom — Wed, 23 Nov 2022 12:03:21 GMT

Thank you Karol. I will be waiting for your reply on that.

Also, is there a way to shift the actual origin to the boundary origin?

Re: Nodal values do not match CFD results

karol.suchon — Wed, 23 Nov 2022 12:13:17 GMT

Ok, sorry for the misunderstanding, I read my message once again 🙂

You should try to find the possibility to read the entire dataset from the Nodal value to the VR.

I do not have an experience with the VR format, but there should be possibility to read it 🙂

Re: Nodal values do not match CFD results

dshom — Tue, 29 Nov 2022 00:18:26 GMT

Hi Karol,

Sorry for the late reply. In order to view the results exactly in VR as displayed in Autodesk CFD, we would require all the values of all possible planes so that no points are missed. Is it possible to read all these plane results automatically? I tried the above methods and all of them are highly time taking methods. Moreover, all the planar points might not be obtained if done manually.

Also, is there a way to shift the actual origin to the boundary origin?

Re: Nodal values do not match CFD results

karol.suchon — Tue, 29 Nov 2022 10:57:41 GMT

I am still not sure if even if we export somehow the data in the grid, that will be a good solution. By that approximation, we could get a lot lower solution resolution than in simulation.

The only way to automate the process is to create the script. We could also try to find software which is able to translate CSV files to gird results, maybe that is a better solution. You could try to check if ParaView is able to handle that.

There is no way to change the coordinate system axes.

Karol

Re: Nodal values do not match CFD results

dshom — Tue, 29 Nov 2022 17:05:13 GMT

Thanks Karol. I could still work with the lower resolution. Could you please confirm on Autodesk's behalf if the feature of exporting is available? If not available, I would look into other methods.

Re: Nodal values do not match CFD results

karol.suchon — Wed, 30 Nov 2022 14:42:56 GMT

Autodesk CFD does not have that feature so probably we will need to use other software as a bridge to translate the Nodal Value to the Gird Values. Paraview could be a good one to check it.

Re: Nodal values do not match CFD results

dshom — Wed, 30 Nov 2022 15:04:01 GMT

Thank you for the confirmation.