RealFlow Official Forum

So there used to be a setting called incompressibility and thank god we're rid of that

But often when an animated geometry breaks the surfacetension, there's jitter spreading across the container, and I think maybe this can be possible to smooth out while meshing, but I want to get your opinion anyway on the matter...

So check out these pictures, we have my GFD which as you can see have a cellsize of 0.021m (geometry scale 0.1) and has 6.8m particles. I've simmed with 1 substep, 0.5 strictness, max 1000 iterations and 0.375 accuracy. There's also a vorticity boost of 0.25 on the domain.
I've only added a gravity daemon. I've had to set the upper setting for the display-range for velocity to 0.5 to be able to show any details at all except for behind the character (that I've hidden).

Then we have the mesh. It's 0.5m faces, and these are the current settings: Originally there were alot of dimples, but I found those probably came from normalization, which I read on the forum to turn off in these cases. Also I guess my particlecount isn't so high after all so I don't want to rely too much on the shape of the particles anyway.

I had hoped to be able to be able to achieve a nearly completely flat surface, before the breached surface tension spreads, as this is supposed to be inside a cave. Considering the details are barely visible in the GFD I'm surprised there's so much detail in the mesh. What do you think I should do to flatten the unaffected parts of the surface, while getting optimal detail around the character interaction?

I think I came along way after removing normalization and raising core threshold, also having a bigger mesh than the default of half the cell seems to help. ould the vorticityboost have caused it? Should I increase accuracy in the pressure solver? Or the substeps?

Thankful for any input on this!

Cheers, Dave

Hi, actually your request

"What do you think I should do to flatten the unaffected parts of the surface, while getting optimal detail around the character interaction?"

is what we do by default with the HY_Mesh default settings.

If using the default settings you get those dimples then probably you have some initial motion in the whole fluid due probably to having some gaps in the walls of the fluid container or something like that.

I think I came along way after removing normalization and raising core threshold, also having a bigger mesh than the default of half the cell seems to help. ould the vorticityboost have caused it? Should I increase accuracy in the pressure solver? Or the substeps?

I don't think the "vorticity boost" parameter is causing that as this parameter only enters the picture when the fluid is actually moving and spinning. The accurary and the other solver parameters are ok by default and definitely I believe they are not the reason of that.

As I said please check the fluid boundaries to make sure it fits properly and there aren't gaps. BTW the frames before the creature enters the fluid are flat when meshed?

Hello Dave,

It could be that the fluid it isn't very deep and core smoothing is not acting at all. Try to decrease "core threshold" in with values in the range bewteen ( 0.0 - 0.4 )

I can not know what it is really happening if I don't see the depth. Could I get the particles files somehow and try some parameterization on my side?

Regards

I was thinking also that I've seen this before when the interacting geometry wasn't water-tight, in some situations the solver just doesn't converge or converge to a wrong solution (right from the solver perspective because the geometry is not water-tight) and the whole container is disturbed.

Please check your geometry, specially the geometry of your character, maybe you can create a proxy out of it, if you haven't done that so far.

I hope this helps.