Ocean sim velocity and foam

[rporter8555]

Is this normal? Velocity changes at the back of a ship-on-ocean sim grid. Notice also a rise in water level at the back of the grid.
Foam does not exit the grid, even with outside life set to 4.0, assuming this is seconds.
Below is the foam.

Below is the velocity preview.

Foam and velocity


Notice the elevated water level at the back of the grid like the grid is partly solid.
I checked to make sure the grid properties "Solid Object" is off, only "Animated Vertices" is active and "Motion Velocity Effect" is 1.0.

Max 2018 Update 20.0-20.2.0.2345
V-Ray 3.60.01
Phoenix FD Version 3.04.01 Nightly, Build ID: 1710077749

Thanks for any insight.
Ron Porter
Mustang, Oklahoma

[rporter8555]

Here's a render.

Ron

[George Barzinski]

Hi,

Is the grid with open or jammed walls? If you want you can send us the scene to check what's going on.

[rporter8555]

Yes, checked that. Grid is open. New grid created from the nightly toolbar.
Don't know if it makes a difference, but I run the water sim first, then copy the aur files to another folder then add splashes and foam as a resimulation pass.
I will send you the scene tonight.
Thanks,
Ron

[George Barzinski]

Why don't you try to simulate all at once (skip the resimulation part)? Then render the result.

[rporter8555]

Hi George,
Really it is about overall project speed and multitasking. I have five slave machines and licenses, all files and models are on a fast shared NAS. I use backburner to put #1 to work on the water, run experiments and make small adjustments quickly until the results are good enough to make the long investment run (takes several days). Then after 500 frames or so I copy the cache to machine #2 and start it to work on the splash and foam resimulation, again running experiments and adjustments until it is good, even while #1 continues to work on the water. Every couple days I copy more sim cache folder to the foam cache folder. Then #3 is set to run final renders from the foam cache with #4 and #5 as render slaves. This leaves my workstation open for modeling. All machines have the same nightly version.
BTW I am always open to suggestions and ideas on how to make the process run faster, but until we can use the slaves as distributed sim engines, this seems to be my best configuration so far.
Ron

[rporter8555]

Here is the sim file.
Ron
Sim55.zip

[George Barzinski]

I understand Ron. Thanks for the scene. I'll tell you what's going on ASAP.

[George Barzinski]

Ok, the first problem with the foam is solved - the particle Age channel must be exported in order for Outside life option to take effect. Also, the Outside life parameter is in seconds and it's counting from the moment foam is born. So, for the test, I put it to 40.

[rporter8555]

Thanks George!
Could we get that turned on in the toolbar preset?

[George Barzinski]

No problem and yes, we can. Thanks for the suggestion.

[rporter8555]

Greetings!

Update.. I thought you might like to see this.

Here are some screen shots of the foam at the back of the grid at frame 700.

Grid size 55.6 Million. SPF 4. Water sim aur cache file size 37MB. Aur file size 380MB after foam resim. Foam sim time this frame 12 minutes. Backup frame size 677MB.

The grid is large enough to allow most of the surface wake action to dissipate, but has a bulge at the back side which seems to be related to the velocity backup shown in my previous posts.

Below with cap mesh. The foam is flying up in an arc then falling back to the ocean level.

Next is with a vray plane at zero elevation to help perspective. Cap mesh render, displacement off.

Now with ocean mesh and displacement off. Foam is flying off the water.

Finally with displacement on. Ocean surface is blended with the grid surface,
Foam is well above the surface behind the grid until it falls back to the ocean, and just forward of the grid back wall some foam disappears below the displaced surface.


For still shots, I might get away with this with a different camera angle. Problem is that the bulge travels with the grid and follows the ship around. Looks odd with animation.
I have tried running the sim with a larger grid, but the velocity bulge is still there.
Suggestions?

Thanks for your time,
Ron Porter

[Svetlin.Nikolov]

I hope in a couple of days I'll be able to check it and see what the problem is...

[rporter8555]

With all the foam channels exported during the water simulation phase, I can resim the foam in a second pass and it has outside life, as expected.
Frames 312, 370 and 755 attached below. My ship is still in construction.

The bulge at the back of the grid seems to have an effect on the wake foam as seen in the video at the attached link.
http://www.portergraphics.us/LUCE/SH...10-20-2017.MP4

Here is the sim file. 3.04.02 Nightly Build ID: 1710127760 Max 2018/V-Ray 3.60.01
Sim57.zip

Any suggestions?
Thanks,
Ron

[Svetlin.Nikolov]

I'm on it. As a workaround, the only thing I can think of right now is to make the container longer so the particles don't have to exit it...

Will keep you posted.