how to plot contour of alpha=0.5 in matlab

JM27 · May 15, 2020, 15:27

Hi,

I want to plot the bubble contour using alpha = 0.5 in order to compare the bubble shape at various times in my simulation. I want to do this in Matlab by plotting various times on the same plot.

I create the contour in Paraview and I save the coordinates of alpha=0.5 contour using File --> Save Data.

The problem is that when I plot the coordinates in Matlab the points are joined differently to what I see in Paraview (see attached image). I have tried sorting the data but Matlab just fills the whole shape of the bubble instead of showing only the outline.

Can someone please tell me how I can solve this problem or a better way to do this?

HPE · May 15, 2020, 17:49

Hi,

Not sure if you are aware of the current forum for the post - hence my message - might be better to raise this question in a MATLAB forum.

Hope you find solution to ur problem.

kerim · May 16, 2020, 21:25

Quote:

Originally Posted by JM27

Hi,

I want to plot the bubble contour using alpha = 0.5 in order to compare the bubble shape at various times in my simulation. I want to do this in Matlab by plotting various times on the same plot.

I create the contour in Paraview and I save the coordinates of alpha=0.5 contour using File --> Save Data.

The problem is that when I plot the coordinates in Matlab the points are joined differently to what I see in Paraview (see attached image). I have tried sorting the data but Matlab just fills the whole shape of the bubble instead of showing only the outline.

Can someone please tell me how I can solve this problem or a better way to do this?

Hi,
Have you used griddata function?

Bodo1993 · October 26, 2020, 12:55

Hi, I use the file 'surfaces' to extract 2D surfaces of the phase fraction from OpenFOAM transient results. I postprocess the data using MATLAB to plot contours of the phase fraction and make videos. I am wondering if I have to use the interpolation function 'griddata' to do so. The problem with 'griddata' is that it takes time to do the interpolation, e.g. a simulation with 100 time steps may take more than an hour to generate the video. Any suggestions?

May 15, 2020, 17:49		#2
HPE Senior Member Herpes Free Engineer Join Date: Sep 2019 Location: The Home Under The Ground with the Lost Boys Posts: 932 Rep Power: 12	Hi, Not sure if you are aware of the current forum for the post - hence my message - might be better to raise this question in a MATLAB forum. Hope you find solution to ur problem. __________________ The OpenFOAM community is the biggest contributor to OpenFOAM: User guide/Wiki-1/Wiki-2/Code guide/Code Wiki/Journal Nilsson/Guerrero/Holzinger/Holzmann/Nagy/Santos/Nozaki/Jasak/Primer Governance Bugs/Features: OpenFOAM (ESI-OpenCFD-Trademark) Bugs/Features: FOAM-Extend (Wikki-FSB) Bugs: OpenFOAM.org How to create a MWE New: Forkable OpenFOAM mirror

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October 26, 2020, 12:55		#4
Bodo1993 Senior Member Join Date: Jul 2019 Posts: 148 Rep Power: 6	Hi, I use the file 'surfaces' to extract 2D surfaces of the phase fraction from OpenFOAM transient results. I postprocess the data using MATLAB to plot contours of the phase fraction and make videos. I am wondering if I have to use the interpolation function 'griddata' to do so. The problem with 'griddata' is that it takes time to do the interpolation, e.g. a simulation with 100 time steps may take more than an hour to generate the video. Any suggestions?