Foam wake coverage

[waaazoo]

Hi,

Long time I wanted to be able to discuss this point and maybe get some hints.

In nearly all simulations I did lately, I find that Foam doesn't behave as it should and that it's difficult to get a natural behavior of the overall shape of foam distribution generated by a ship hull.
Please look at attached picture. The photo is from a 12m yacht tender travelling at about 30knots. The foam creates a shape due to the hull hitting the waves. Sometimes the foam spreads far away from the hull, sometimes it's closer, creating, let's say, a Christmas tree shape
When simulating this (I have the same exact hull of this tender), it's impossible to get such a nice shape. I tend to get something like drawn on 2. I animated the hull with vertical, tilt, roll movement. I can get some sort of Christmas tree shape, but never as large as the reference photo.
My feeling is that the foam is not travelling far enough, in a general manner. Droplets surfing is at 1, but I would have liked to be able to "push" that setting.
This issue is something I noticed all over the different simulations, whatever the hull, whatever the speed of the boat. In reality, the foam generated by the hull is really rolling over the water.

I'm sure i'm not the only one experiencing this issue. Can you give any comments, any hints ? Maybe I missed something, somewhere.

[Ivaylo Katev]

The real boats are not moving straight forward, they have significant up-down movement due to the interaction with the water (even if no waves are present). This behavior is most pronounced in the very fast boats known as "jets", they literally are jumping over the water. Try to animate this kind of movement and i'm almost sure the wake will get closer to the refferences

edit: i saw you wrote that already have this kind of movement. Well, the only thing that remains are real waves, interestingly waht will happen if you use the wave force with moving grid, perhaps this can give the result you need

[Svetlin.Nikolov]

Yes indeed, I'm also thinking about some improvements to foam sliding over the liquid surface....

[waaazoo]

Hi,

Thank you both for your comments.
Ivaylo, yes, I have some movement on the boat which was discussed with the naval architect. It should be accurate, but I have maybe to try to exaggerate it a little.
Svetlin, it would be great if the foam would be able to slide more over the ocean surface. I think that in the current versions it doesn't enough and tends to stick to the water.
I made already some progress by adding "air effects" and bumping up "liquid like", but the shape seen from top is still far away from the photo. I miss this ability of the foam to expand outboard.

cheers,

Olivier

[waaazoo]

Hi,

We difinitely need more surfing. I'm at droplet surfing 1, but I would need to bump it up at least to 5 or have a "sliding" parameter especially for foam!
One other thing I can think about is a "dispersion" parameter. As the foam is not directly interacting with the ocean texture, there could be dispersion parameter to simulate calm or wavy sea while the foam and splash is surfing. One cool thing would be if we could plug into the foam the ocean texture for this "dispersion".

Here is a simulation of a 80m yacht at 20 knots. Overall, it looks already cool, but it would be way better if there is more surfing/sliding. Same applies to the speedboat posted above.

https://vimeo.com/362505246

This scene is similar to the scene at 00:20 in this video : https://vimeo.com/362306683

I'm still trying to improve but I'm also eager to see what you can do in terms of software improvement for next version of PhoenixFD.

[Svetlin.Nikolov]

We just gotta see it there will be time to make any of these changes for Phoenix 4.0 or for a later version...

[waaazoo]

Thank you Svetlin. I look forward to see the news on FD4.

[JuhaHo]

This may be a bit off topic, but I say this anyway. Is there any information on how much the water temperature will affect foam on boat wakes? I took a few hours boat trip to an island earlier today. As always, I observed very carefully my own as well as the other boaters wakes. I noticed there was a very little foam on boat wakes today - or even next to nothing. I wonder if the water temperature has something to do with it. This time of year here in Baltic sea there's only few degrees Celsius above the zero. The water feels much "harder", the splashes to windscreen seem to hit with more power than on summertime. Or is it only in my imagination?

[waaazoo]

Yes indeed, I'm also thinking about some improvements to foam sliding over the liquid surface....

Hi,

Any news on improving the sliding foam on surface ?

cheers

[Svetlin.Nikolov]

Hey, not yet, this got offset way back by a ton of other tasks...