Sailing Yacht foam control

[MartinDarzacq]

Hello, I have been experimenting with Phoenix the past few days, trying to create waves and splashes behavior from the chaos boat tutorial as a base. However, I don't manage to create something believable. Maybe you will have some tips? Here are some references I'm trying to achieve:

[georgi.zhekov]

Hey,

Can you show us the result you're getting and the settings you used ?

[MartinDarzacq]

It's coming I'm trying to get through uploading errors

[MartinDarzacq]

And here are few of my attemps. Either I don't have any foam, or I have foam but I made the boat moving way to fast and looks more like a jetski. Also my main issue is to have the foam to spread out from the hull to the sides.

[MartinDarzacq]

The setup is almost the same as the tutorial, with 2 boxes with faces ID as liquid source. 100M+ cells.

[Svetlin.Nikolov]

Sounds like you are looking at this tutorial: https://docs.chaos.com/display/PHX4M...p+in+the+Ocean

In it, I believe the ship is definitely larger than your boat, so it would generate more foam while moving at the same speed. If you've read through the tutorial, you saw that the natural Foam birth is disabled by setting the Foam Birth option to 0, and instead only Foam On Hit is used, which creates foam when the splash particles hit the liquid surface. Check here for more info on how the FLIP particles transform into one another: https://docs.chaos.com/display/PHX4M...les+Life+Cycle

So in order to create more foam while keeping the Foam On Hit technique, you have two (even 3) choices:
- Create more dense foam in the same places it appeared before - by increasing the Foam On Hit value, or/and by increasing the Splash Amount;
- Create foam with the same density as before, but in new places - by decreasing the Splash Birth Threshold.

Cheers!

[MartinDarzacq]

Hello, thanks for your answer. That is indeed the tutorial. My boat is thiner and I don't expect this level of large foam spread, yet when I look at references the foam clearly don't just stick to the hull. I confirm that I used the Foam on hit only.
I feel that the foam is already way too dense and not scattered enough, but I will play with the settings you mentioned and keep you in touch with the result. Cheers!

[MartinDarzacq]

I'm sharing the first test wich is not good, but I'll keep experimenting increasing the settings. I used here:
foam on hit: 6
splah amount: 30
threshold: 3
half life was 1,5, I will also increase it hoping to get some foam gliding from the boat sides to it's trail


I also sliced the hull in 2 parts, increasing the front prow motion velocity to 2 to get a bigger starting wave, this part seems working.
I also share my animation settings, wich might be part of the problem if my maths are wrong, I don't know: 1000 frames, 30frames/second, so 33 secs animation length. The boat moves 300 meters in Y axis, so 9meters/sec or 32km/h

[Svetlin.Nikolov]

Oh, looks like splash starts getting born elsewhere in the grid as well, which means the splash threshold is probably too low right now already.

An alternative approach would be to allow direct foam birth in addition to the foam born by the splash - from the Foam rollout, please increase the Foam Amount and adjust the Foam Birth Threshold value - this should allow for more foam to be created as well.

The approach with splitting the ship into two parts is also very clever!

[MartinDarzacq]

I managed to do a dozen of simulations, sad It takes so long each time. Thank you I will try the foam rollout.

-Can you confirm that if I'm not happy with the strenght of the waves, that this is only due to the ship's shape and it's speed? maybe I have to cheat more and increase a bit the boat's speed
-The image attached started to look interesting as the foam was more scattered, however the grid lines seems to generate weird foam lines...is it due to my threshold being too low too?

Cheers

[Svetlin.Nikolov]

Yes, the shape and the speed should be the only factors that affect it.

Indeed if you lower the threshold, particles would start spawning on the sides, but you can control this by connecting a Birth Volume for the Foam and Splashes - for example a non-solid, not renderable box that fits inside the simulator and is narrower and shorter than it - it would define the allowed zone in which these particles can be born naturally.

[MartinDarzacq]

Update: after a lot of trial and error, I'm starting to obtain a base to work with. It felt way easier to create something believable for a high speed object out of the box, trying to achieve a more subtle effect for a lower speed sailing boat required a lot of testings.

I Had to cheat and increase the boat speed, use motion velocity 3 for the front prow and 1 for the rest of the boat, to get a bit of a wave at the front prow. Even if that front wave looks a bit "low poly".


Sharing main settings:
>100M grid
Splash amount: 30
Foam on Hit: 9
Splash amount: 3
Threshold 3,5
Half life 4
Velocity of the propellers : 14m

Edit: did not mention the foam parameter as I probably used too low settings to make it noticeable

[MartinDarzacq]

The main issue I have right now is that theses weird lines created by the liquid simulation. I thought that the ocean texture displacement would be enough to hide them, but they remain visible. Any idea to fix this?

[Svetlin.Nikolov]

Ah, yes, we've seen these, but are yet to find the problem for this issue and solve it..

[MartinDarzacq]

Oh, that's sad. Still, I am trying to learn more about the software and make the foam behavior more "believable", please find illustrated on the image attached my questions, I'm interested in your opinion:

1 the foam is progessively disappearing on the surface here but you can still see it through the water. Do you think this could be achievable playing with half life settings and water material's fog depht?
2 the front prow is pushing the water on the sides quite far creating a wave, but the boat does not seem to go particulary fast. is the shape of the prow the main factor?
3 the foam is really consistent on my simulations, but here you can see a more irregular pattern with spots without any foam, feeling a bit more realistic. is this something we can create?
4 as the ocean surface is generated by the displacement, is there a way to "scatter" some additional foam particles around, as the wind creates in real life?

Thank you for your time