Post processing for free surfaces

Cdc73

Hi !

I need to post-process a simulation with a free surface, so as to count the particles belonging to this free surface. By free surface particle, I mean a particle with no neighbors on one side : a particle in contact with a boundary should not be counted.

Any idea ?

My final target is to calculate the sum over time of all the free surface particles.

Thanks in advance.

Asalih3d

Just throwing it out there but a simple solution might making a piece of code which sorts particles based x a very small x interval:



And then the free surface would be the particles with the heighest z position.

Please note that this this solution is not useful for more complex cases, but this might be a quick and dirty solution, as long as it is possible to make the x interval sufficiently small.

Edit: Actually this might no be effective if you have some sceneria to like the right of the included picture - the free surface would there be on both sides. Keeping the comment up if it might be helpful for anyone anyways.

Cdc73

Thanks for the answer Asalih3d.

For the time being, since I cannot modify the code itself, I'm working on the *.vtk files.

I'm using two files : the "bounds" file, and the "isosurface" file, checking all the distances between pairs of points. If, for a specific point belonging to the isosurface file, the distance to all the points of the "bounds" file is more than a specific threshold, I considere the point as belonging to a free surface. Quite a long and clumsy processing... !

Asalih3d

Ah okay that is also a viable way of doing it - if you want I guess you could use the threshhold of your computational domain instead to simplify more complex cases a bit, but you will know better if that works or not for you.

Ideally it would of course be nice if there was a way to see which particles were considered "Free Surface" during simulation, but as far as I know there is not. Maybe someone else will chime in with a piece of gold soon :-)

Alex

MeasureTool allows you to compute the surface elevation (-height) along the simualtion at fixed positions.

Regards

Cdc73

Many thanks for your comments guys.

My target is to get a measure of the time spent by each particle at the free surface. I'm dealing with a problem of gas pick-up, and I need to get a measure of the amount of contact between the simulated fluid and the outside atmosphere.

In fact, the ideal situation for me, would be to get a simple indicator generated by isosurface.exe, which would tell for each surface node, if it is in contact with a boundary or not.

Do you think this kind of small modification of isosurface.exe could be taken into account in a future version ?

Best regards.