Learning Forum

[rkoomul]

I am simulating diffusion of a UDS in a domain and I am looking for a way to mark all cell-faces on a boundary which has a UDS concentration above a specified threshold.  Also, I need to calculate the total area of all these marked faces.  The goal of this modeling is to find an optimum UDS source location to get the maximum boundary cell-face coverage.  Since it is an optimization problem, I have to calculate the area covered multiple times.  So, I am looking for an automatic way to do this.  What is best way to do this?

Thank you in advance.

[DrAmine]

You Can use cell register feature to mark the regions where UDS is in certain range, below or above some threshold value.

[rkoomul]

Thank Amine for the reply.  Could you please elaborate a little more how to do it? Do you have any examples for any similar problem?

Thank you,

[DrAmine]

Something old but might be helpful: 

 even if for initialization purpose.

In new versions better to use Cell Registers and then select UDS as Field variable.

[rkoomul]

Thank you Amine.  I tried cell-registers using field variables. But, there is no option in it to select boundary surfaces to specify the range for the field variable.  Please see the image in the attached file.  Also, I checked the cell registers based on boundaries. But, there is no option in it to specify the range for field variables.   Any suggestions?

 

[DrAmine]

What do you want to do? You want to mark only cell near surfaces where UDS is above certain value?

[rkoomul]

We are trying to find an ideal location of a medicine injection to an anisotropic medium. This is an optimization problem, and the cost function is the maximum surface area coverage by the medicine and the independent variable is the location of the medicine injection. So, during each optimization run, we need to mark all boundary cell-faces which has a medicine concentration above a threshold value and we need to calculate the total area of these marked cells.

[DrAmine]

So you need to get the faces if the boundary which depict certain value. Okay...
Does looking into contour plots and showing the uds value atvthe surfaces and clip to range a good start?

[rkoomul]

That will give a qualitative description, for visualization.  But, it will not give the quantitative data data that I need for optimization.  For optimization I need to define cost function, which is the area of coverage that I described earlier.  

[DrAmine]

But you can clip the surfaces based on the yes value range. You can then get the area of the clip.
I am only providing this simple suggestions before you need to use UDF.

[rkoomul]

Thank you Amine.  As you suggested, I was able to clip the boundary surface using "Setting Up Domain -> Surface -> Create -> Iso-clip".  Then, I created a new "Report Definitions -> New -> Surface Report -> Area" and selected the clipped-scalar to watch the area coverage as the simulation progresses. I was able to see the change in area coverage using a report monitor.

Is there any similar option available for volume clipping?  I tried "Setting Up Domain -> Adapt -> Mark/Adapt Cells", and marked the iso-value region.  I could visualize the selected region using "Manage Registers -> Display". But, this marked region is available when I create a report to calculate the volume of the selected region.

Thank you.

[DrAmine]

Actually quick ansewer is no. Let me think about that and update later.

[DrAmine]

After thinking about it: No. You need an UDF. One can try to mark the cells and use that to separate the zones but not ideal. In the next versions there will be a workaround via Expressions. 

Best workaround is to use CFD-Post for that and create a Volume Clip. Afterwards you can measure the volume of that clip.