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Making a 2D velocity plot from a 3D geometry.

Posted Mar 7, 2017, 10:59 a.m. EST Fluid & Heat, Computational Fluid Dynamics (CFD), Geometry, Results & Visualization Version 4.1 4 Replies

Cesar Araujo
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I have solved a 3D CFD model and I wish to have 2D plot of the velocity along the geometry height at a certain point inside the geometry. How can I do that? I appreciate your help.
4 Replies Last Post Mar 8, 2017, 4:27 a.m. EST
Grayson Hawkins
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Posted: 8 years ago Mar 7, 2017, 3:54 p.m. EST
Cesar,

I have not found an exact way to do this, but I have jerry-rigged the following solution in COMSOL 5.2a:

1. Create a 3D Plot under Results, right click the new 3D Plot and add "Surface"
2. Set the surface to read your Velocity variable (default spf.U)
3. Plot
4. Now, you can click along the 3D model in the model viewer, and COMSOL will create a table giving you the X,Y,Z coordinates and the value of the velocity at that point.
5. Click along the line that you want to graph
6. Import values to Excel

Regards from Tennessee,
Grayson
Cesar, I have not found an exact way to do this, but I have jerry-rigged the following solution in COMSOL 5.2a: 1. Create a 3D Plot under Results, right click the new 3D Plot and add "Surface" 2. Set the surface to read your Velocity variable (default spf.U) 3. Plot 4. Now, you can click along the 3D model in the model viewer, and COMSOL will create a table giving you the X,Y,Z coordinates and the value of the velocity at that point. 5. Click along the line that you want to graph 6. Import values to Excel Regards from Tennessee, Grayson
Cesar Araujo
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Posted: 8 years ago Mar 8, 2017, 2:20 a.m. EST
Hi Grayson,

Thank you very much for your answer. Indeed, by this method I am able to plot the velocity along the axis, as I primarily intend. However, the results might not be as accurate as I desire. Nevertheless, that will be my 'goto' method from now on.

I know for a fact that it is possible to compute this velocity in a more precise manner by using certain functions and commands within COMSOL. I just ought to find out how to make it happen.

Regards from Göteborg,
Cesar
Hi Grayson, Thank you very much for your answer. Indeed, by this method I am able to plot the velocity along the axis, as I primarily intend. However, the results might not be as accurate as I desire. Nevertheless, that will be my 'goto' method from now on. I know for a fact that it is possible to compute this velocity in a more precise manner by using certain functions and commands within COMSOL. I just ought to find out how to make it happen. Regards from Göteborg, Cesar
Gunnar Andersson COMSOL Employee

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Posted: 8 years ago Mar 8, 2017, 2:35 a.m. EST
Do you want to create a 1D plot of the velocity as a function of the height along a line? Then I think that you should consider using a Cut Line data set.
Do you want to create a 1D plot of the velocity as a function of the height along a line? Then I think that you should consider using a Cut Line data set.
Cesar Araujo
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Posted: 8 years ago Mar 8, 2017, 4:27 a.m. EST
Hi Gunnar,

Exactly! That was the functionality I was looking for. This is how I did it following your cue:

I) Right click on 'Data Sets'
II) Choose 'Cut Line 3D'
III) Specify the coordinates of the line
IV) Right click 'Results'
V) Select '1D plot group'
VI) Right click '1D plot group 1' and select 'Line graph'
VII) On the settings of 'Line graph' select the Data set 'Cut line 3D 1'
VIII) Choose the expression in the y-Axis data. Leave the x-axis data as "Arc length".
IX) Plot

*I am using COMSOL 4.1

Thank you very much Gunnar. Problem solved!
Hi Gunnar, Exactly! That was the functionality I was looking for. This is how I did it following your cue: I) Right click on 'Data Sets' II) Choose 'Cut Line 3D' III) Specify the coordinates of the line IV) Right click 'Results' V) Select '1D plot group' VI) Right click '1D plot group 1' and select 'Line graph' VII) On the settings of 'Line graph' select the Data set 'Cut line 3D 1' VIII) Choose the expression in the y-Axis data. Leave the x-axis data as "Arc length". IX) Plot *I am using COMSOL 4.1 Thank you very much Gunnar. Problem solved!

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