Ocean Simulation Wave Resonance Problem

[vittorio.p]

Dear All,
I'm new on the forum, I'm working with phoenix/vray/3dmax since fiew years, i did many animation on phoenix for commercial project.

After fiew update of phoenix (i'm running the last update) we still have to fight with some bugs, I want to share it with you to ask if I'm doing something wrong or if it's actually something to solve differently.


I'm running a 100ft yacht with ocean simulation, crusing speed 12 knots distributed in 1500 frames with 50.000.000 particel.
After 550 frame, faom and splashes started appearing correctly and quite good appeal, but then started problem, a sort of resonance on the surface, a repetition of small crest wave create splashes and foam all over the ocean surface just into the simulation box. This compromise the all simulation result. Have a look at the picture:



Sometime this happen, sometime not, I did fiew other simulation on different size, resolution and yacht range, but we experience that fiew times when we increase resolution, but I absolutely dont know how to solve it.
Usually I replace the simulation, reduce a bit the cruising speed and resolution, but surely this is not the way we want to work with it.

here you can also find phoenix setting




Can you tell me what's going on?

thank's for support.

Vittorio

[Svetlin.Nikolov]

Hey,

Can you please check a latest nightly build? There were bugs where particles were born on the simulator borders, but all should be fixed now. In the nightly you'd also find Birth Volumes for foam and splash and you can limit the areas where new particles appear. If you don't see "Phoenix FD 3 for 3ds Max" in https://nightlies.chaosgroup.com, please contact support@chaosgroup.com and they will take care of your access rights.

Cheers!

[vittorio.p]

Thank's Svetlin,
I don't see any update, I have contact the support and wait for their replay, hope to solve it anc continue testing.
We have fiew other thinks to share, but I will post it one by one after solving the first one.

Cheers!
Vp

[Ivaylo Katev]

in the most cases problems like this are spf related, try to increase a bit the spf, perhaps 6 is a good value.

[vittorio.p]

I did fiew test during the last 5 days with the nightlies version ad seems the problem of simulator boundaries to create particel it's solved, and that a good news for sure, I will also try to increase the spf as you suggested me.

By the way, I have still other problem, with this new release parameter concerning foam and splashes work completely different, I did a very long simulation at least 72h to see how particel will work after 1000 frame and 400 meter navigation.
it ended up with something different from previus simulation.

Look at this:





well good thing it that wave simulation look more real and the way how they open from the aft, also the creat look good.

the things I have to solve now are:

_the liquid (ocean) seems jellyfied or close to freeze temperature, especially at the border of the aninimation

_Foam and spashes aren't enought to recreate a realistic simulation (I did 70k particel in grid, 20k more than previus one)

_Dimension of the bubble didn't respect the dimension I used on the previus version, they are set at 0.03 (30cm) but they looks like bigger then fiew meter, you can see it on the top image on both the side of the hull


from this picture I did with the previus version you can see that the pattern and the bubble into foam worked better:






liquid generated in the aft with the newest version it way better, but foam and splashes with the setting I used before are way to far from the old one.
what do I have to change to optain again this quality in simulation?

cheers!

[Svetlin.Nikolov]

Hey,

The differences are because it's an entirely new solver and it works in a completely different way than the old one. The simulation settings are converted approximately, but you need to do some tweaks. Regarding the dimensions of the bubbles, maybe you mean the Splash particles? I'm asking because the foam particles should have the same sizes now with 3.0's FLIP solver, but the splash particles do not have an adjustable size anymore - their sizes are instead determined by the cell size of the grid.

If you need foam to appear in more places, then you can decrease the foam birth threshold. If you need more foam to be generated at the places where it's currently born, then you should increase the foam amount.

Not sure about the jellified ocean, but I'd guess that this is how it looks when there is not enough foam over the liquid?

[vittorio.p]

I Svetlin,
The dimension of the bubble I'm talking about is this one, I would like to obtain again this variation of small bubble into the foam pattern



I'm Actually testing a new simulation with decreased birth threshold ( vel.threshold right?) and i also increased the foam amount, which should be set at 0 following the tutorial, but now I set it at 1, which should be a good number to set for testing?
Are always proportional inverse birth amount and threshold? either on the splashes?

Concerning the jellified ocean I think it's cause of the lack of foam and splashes.

I also changed the value of step per frame to 6, but after fiew frame with changed faom parameter I see again simulator generate particel from the border of the grid, and surely this will move to the aft increasing it's intensity.



How to solve it?

thanks again for support.

[Svetlin.Nikolov]

Hey,

Can you test it with a latest nightly build? We fixed a similar issue with foam appearing at the borders a few days ago. The nightlies are at https://nightlies.chaosgroup.com and you should ask Support for access if you don't see Phoenix 3 there.

Your settings sound good if you are looking for this kind of result. If you need to control the sizes of the particles, then you should also check the two 'variation' parameters.

[vittorio.p]

Ok I will install the last nightlies and test it,
Keep in touch

cheers!

[vittorio.p]

I tried the last nightlies, but I have to tell you nothing changed on the bug of foam creation from border.




what should I do?

[Svetlin.Nikolov]

Hmm, from this pic it seems like the vel. threshold is too low - you should set it higher, or foam will appear all over the place. From the previous screenshot it looked like a bug we fixed recently, but now this looks like the threshold is to blame.

[vittorio.p]

ok right, i'll try to increase it a bit and resimulate. If I set a high value for the threshold I will loose lot of detail into the foam generated by the boat navigation, how can i balance it?

[Svetlin.Nikolov]

In this case, you can try keeping the high threshold and use a Foam Birth Volume - it will confine the natural birth of the foam only around a certain geometry such as the boat, and you can make it fade out with distance too

[vittorio.p]

Well working on the vel. threshold and the foam birth i'm not so far from a good result, the only think that I continue to see wrong it's the bubble dimension.



as you can see the booblu dimension it's set at 30 cm, but the result I see it's larger then 3 meter.
can you tell me something about?

[Paul Oblomov]

That is patterns Roughly 3m you set