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December 14, 2019, 01:55 |
interface curvature in interFoam
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#1 |
Senior Member
Nguyen Duy Trong
Join Date: Apr 2014
Posts: 124
Rep Power: 12 |
Hi everyone,
I have a question about interface curvature as below: Following definition of interface curvature, is defined as: in which is normal vector of interface that is defined based on volume fraction in each cell as: So: is volVectorField and then is volScalarField, is that correct? However, in interFoam solver, is defined on cell face () as: where is defined by interpolation computation as: then, face unit interface normal flux is defined as: with is the normal vector of cell face (Note that then is a surfaceScalarField). Then, interface curvature is defined as: My question is: - why do we need to interpolate the to cell face. - when we mention about normal vector of interface (interface normal vector) which one is correct defined at cell's center or defined at cell's face? |
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December 16, 2019, 08:36 |
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#2 |
Member
Hosein
Join Date: Nov 2011
Location: Germany
Posts: 93
Rep Power: 14 |
Hii there,
1. In order to be consistent with FVM, fluxes/forces or ... are calculated over the faces of the computational cell. Also note that surface tension is added as a volumetric force in momentum equation. 2. In general, VOF methods which are not tracking explicitly(by reconstructing the interface) the interface, are not representing the exact shape of the interface. This means you should not worry about which one is correct or not. As far as solution of momentum eq. is concerned the formulation should be done WRT cell faces. hope this helps... |
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December 17, 2019, 18:18 |
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#3 | |
Senior Member
Nguyen Duy Trong
Join Date: Apr 2014
Posts: 124
Rep Power: 12 |
Quote:
Thank you very much for your comments. I have another question on comment #2. Could you please make clear on VOF methods which are not tracking explicit, why it does not represent the exact shape of interface? What are their drawback make interface not sharpen? |
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December 20, 2019, 05:37 |
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#4 |
Senior Member
Michael Alletto
Join Date: Jun 2018
Location: Bremen
Posts: 615
Rep Power: 15 |
the interface is not explicit since it is calculated from the colour function alpha. One disadvantage is that if you consider also surface tension with an implicit formulation of the interface you can generate parasitic currents. A very good article explaining interfoam is this one: https://iopscience.iop.org/article/1.../1/014016/meta
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December 22, 2019, 22:49 |
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#5 |
Senior Member
Nguyen Duy Trong
Join Date: Apr 2014
Posts: 124
Rep Power: 12 |
Dear Michael,
I thank you very much for your comment with related paper. |
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