How to get interpolated values of isosurface

AdamAL · January 8, 2014, 12:08

I have a solution with a wavy free surface (air/water interface - marine environment). Within Fluent i can create a nice looking isosurface of the interface (using volume-fraction = 0.5). It looks nice and sharp, so Fluent is clearly interpolating to get a more exact fit than simply "center of cell containing VOF-fraction<1".

However when I try to export the surface's data, (file>write>profile: [surfaces: isosurface, values: y-coord], I get some very jagged data - presumably corresponding to "center of cell cut by isosurface".

I suppose I could export the volume fraction in the entire domain and recreate an isosurface in another postprocessing tool, but that would A) duplicate a lot more data, and B) require redoing the work that Fluent has already done (fitting the isosurface).

Does someone here know of a better solution?

AdamAL · February 10, 2014, 16:53

For the future googler. It turned out I was not completely right.

If you export profile with cell values, and choose y-coordinate as the parameter to export, then yes,
the parameter in the resulteing .prof-file will be the cell-coordinate-not the iso-surface coordinate.

However, Fluent also exports the x-, y- and z-coordinates of the surface itself.
I.e. you have to use those values instead. These fields are simply called 'x', 'y', 'z' (as opposed to 'y-coordinate').

January 8, 2014, 12:08	How to get interpolated values of isosurface	#1
AdamAL New Member Adam Læssøe Join Date: Nov 2013 Posts: 29 Rep Power: 12	I have a solution with a wavy free surface (air/water interface - marine environment). Within Fluent i can create a nice looking isosurface of the interface (using volume-fraction = 0.5). It looks nice and sharp, so Fluent is clearly interpolating to get a more exact fit than simply "center of cell containing VOF-fraction<1". However when I try to export the surface's data, (file>write>profile: [surfaces: isosurface, values: y-coord], I get some very jagged data - presumably corresponding to "center of cell cut by isosurface". I suppose I could export the volume fraction in the entire domain and recreate an isosurface in another postprocessing tool, but that would A) duplicate a lot more data, and B) require redoing the work that Fluent has already done (fitting the isosurface). Does someone here know of a better solution?

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February 10, 2014, 16:53		#2
AdamAL New Member Adam Læssøe Join Date: Nov 2013 Posts: 29 Rep Power: 12	For the future googler. It turned out I was not completely right. If you export profile with cell values, and choose y-coordinate as the parameter to export, then yes, the parameter in the resulteing .prof-file will be the cell-coordinate-not the iso-surface coordinate. However, Fluent also exports the x-, y- and z-coordinates of the surface itself. I.e. you have to use those values instead. These fields are simply called 'x', 'y', 'z' (as opposed to 'y-coordinate').