Smoothed VOF gradient

- April 14, 2022 at 8:43 am
  
  prebenjs
  Subscriber
  
  What does the Smoothed VOF gradient really show. I read the the guides but couldn't really get a good grasp of what it really is. Is it a good measure on interfacial diffusion between phases ?
- April 14, 2022 at 8:34 pm
  
  KR
  Administrator
  
  Hello:
  Please review this link.
  37.4. Alphabetical Listing of Field Variables and Their Definitions (ansys.com)
  Karthik
- April 15, 2022 at 7:15 am
  
  prebenjs
  Subscriber
  
  I've read this, but as mentioned It would be nice with some more explanation about what this really measures, in a more "practical" way.
- April 15, 2022 at 11:26 am
  
  aitor.amatriain
  Subscriber
  
  The smoothing process is based on the volumetric average over the cell neighbors
  43.14.2. Patch Dialog Box (ansys.com)
  It is essentially a simple filter.
- April 16, 2022 at 9:37 am
  
  prebenjs
  Subscriber
  
  Yes, but what does the quantity of the smoothed VOF gradient really tell you ? Is this a measure that can be related to the interfacial diffusion between phases ?
- April 16, 2022 at 4:15 pm
  
  aitor.amatriain
  Subscriber
  
  I guess that it could be useful for post-processing in the case of coarse meshes.
  The phase continuity equation does not have any diffusion term, so all values that are not 0 or 1 are essentially caused by numerical diffusion.
- April 17, 2022 at 10:24 am
  
  prebenjs
  Subscriber
  
  Maybe. But the meaning of the term Smoothed VOF gradient, do you have any easy explanation here. I guess one can say that it could be seen as a blending of volume fraction due to discontinuities or to allow mass balance in steep gradient areas, where blending is used as a tool to avoid discontinuities in the numerical values.
  Do you agree with this representation of the smoothed vof gradient ?
- April 18, 2022 at 2:41 pm
  
  DrAmine
  Ansys Employee
  
  Quantity used for curvature calculation and surface tension force.
- April 18, 2022 at 2:42 pm
  
  DrAmine
  Ansys Employee
  
  And one can use it or smooth vof field to add some smoothness when dealing with phase change which relies on interfacial area.
- April 19, 2022 at 11:26 am
  
  prebenjs
  Subscriber
  
  Okay, So generally it will say something about the numerical diffusion between the phases caused by surface tension forces ? I don't get what you mean by your last comment.
- May 14, 2022 at 8:36 am
  
  prebenjs
  Subscriber
  
  ?

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