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-   -   Moving surface (with swak4Foam perhaps?) (http://www.cfd-online.com/Forums/openfoam-pre-processing/129576-moving-surface-swak4foam-perhaps.html)

 cosbergel February 7, 2014 15:08

Moving surface (with swak4Foam perhaps?)

Hi guys,

Does anybody know if I can have a moving surface (maybe using swak). Something like :

planeAverage
{
type swakExpression;
valueType surface;
surfaceName surface;
surface {
type plane;
basePoint (0 \$expression 0);
normalVector (0 1 0);
interpolate false;
}
verbose true;
expression "blabla";
accumulations (
average
);
}

Thank you
Kostis

 immortality February 10, 2014 16:42

what do you intend exactly? do you want to obtain averages on a moving wall? how it moves?

 cosbergel February 11, 2014 13:00

I am simulating a falling droplet and I would like to define a moving surface inside my domain which will have fixed distance from the interface of the droplet in order to calculate the drag force by integrating the momentum flow rate across the particular plane.

 gschaider February 14, 2014 12:18

Quote:
 Originally Posted by cosbergel (Post 474508) Thank you for the answer. I am simulating a falling droplet and I would like to define a moving surface inside my domain which will have fixed distance from the interface of the droplet in order to calculate the drag force by integrating the momentum flow rate across the particular plane.
Interface of the droplet (assuming you're using interFoam) you can get with a isoSurface sampled surface. Distance from that surface is a bit more tricky. There comes a plugin-library with swak that defines functions related to sampled surfaces. One of them generates a field that is the distance from a surface.

So one way to do this (if I understand your problem correctly) would be with a sequence of functionObjects:

- generate iso-surface sampled Surface
- generate a field with the distance from that surface (but only use the values where alpha>0)
- from that field generate another isoSampled-Surface
- do your evaluations on that

Have a look at Examples/other/angledDuctImplciit. I think that is where I test these plugin-functions

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