Boat simulation; issues with active body

[Svetlin.Nikolov]

We have a ton of tests running every day, so this should (tm) not have changed.

If you can find a scene that behaves differently between Phoenix 3 and Phoenix 4, please please please share it, so we can make sure they behave identical again.

[JuhaHo]

Here's somewhat similar hull simulated with Phoenix 3 by using out of the box settings. It looks much like actual photo I posted earlier. As a workaround,is it possible to install the two versions on simultaneously. I could do the active body simulation with PH 4 and on second pass the water simulation with PH 3.

There's no way I can share the hull geometry. That's why I asked if You have speedboat CAD-models for simulation testing of Your own. For the simulation You need also speed, position and ride angle information.

[Svetlin.Nikolov]

I don't think we have this kind of models and it wouldn't really matter without your exact scale, settings, animation, etc. Overlooking one small thing can sometimes make a huge difference, so all details matter.

The only way I could help in this case is by explaining what we would do here if we had the scene, or scenes (initially I though it was the same scene, but now sounds like there are two different scenes?). Here it goes:

If you have a scene from Phx3 that behaved like you wanted, try something else - export a pair of simulation presets - from the old scene and from the new one, and either attach them here, or compare them yourself with a diff tool - the parameter names inside are the MaxScript names. Of course you need to make sure your Sources are equal, your scene scale, all your animations, all the involved models, but this would at least be a start in getting inspiration as to what parameters might differ that made the old scene work one way and the new one - differently. Ah, also - if your old scene does not have active bodies and the new one is an active body simulation, you either have to disable the active body sim in the new one, or transfer the animation to the old one, otherwise it would be comparing apples and oranges again.

There is no way to have two versions of Phoenix for the same 3ds Max or Maya simultaneously - only in case you have more than one 3ds Max (or Maya) versions, you can install many Phoenix versions at the same time. The install takes literally 15 seconds though, unless you need to install it on several remote machines...

Cheers!

[JuhaHo]

I opened an old Phoenix 3 scene (the same as rendered above) and ran the simulation again. The simulation was fine. So it looks like all the problems are on simulators that I've created with Phoenix 4 - confusing.

[Svetlin.Nikolov]

Did you try my other suggestions?

[spaceRick]

Thanks,

I changed the Motion Velocity to 10. I still can't see much wake on the sides, but foam and splashes are getting a bit wild. I have used extreme foam values and try to modify those next.

hey,i'm not fully up to speed with how you've set this up and i'm not sure what the shape of the hull you are using is below the waterline, but in this image there doesn't seem to be a deep enough trough for the hull to even make a wake? - is the geo airtight, are the normals correct and could this be a clear-inside problem? the look of this image you've posted reminds me of a previous clear-inside problem I had. as a workaround, plus a way to fast-track some velocity in the grid I find it' good to initialize the sim by having the boat above the water and gently lowering it in at the start of the preroll over a few dozen frames.

I'd also disable the displacement when judging the result as depending on the map that's driving it; it can give you a false sense of how deep the hull is in the water.

[JuhaHo]

I got a new hull model, so I need to create a new simulation. I have two issues here: There's no foam on the sides of the boat and the green drive emitters are not generating any foam. Any ideas to try.

[slavina.nikolova]

Hey,

As for the Foam - the foam amount depends on the birth threshold for the foam. You can check how each particle type is born and dies here - https://docs.chaosgroup.com/display/...les+Life+Cycle
Generally, in your case reducing the Foam Birth Threshold should help to create foam around the ship.

As for the green primitives - are they selected as Emitters in the Source List? You might want to choose only the back faces of the cylinders to be emitters. To do so, select the cylinder, add an Edit Poly modifier, go to Face selection mode and set the ID for all faces to 1 for example. Then, select only the face pointing in the back direction and set its ID to 2.
Specify the Polygon ID for emission to be 2 at the bottom of the Phoenix Liquid Source parameters panel.


Hope this helps!

[JuhaHo]

Hey,

As for the Foam - the foam amount depends on the birth threshold for the foam. You can check how each particle type is born and dies here - https://docs.chaosgroup.com/display/...les+Life+Cycle
Generally, in your case reducing the Foam Birth Threshold should help to create foam around the ship.

As for the green primitives - are they selected as Emitters in the Source List? You might want to chose only the back faces of the cylinders to be emitters. To do so, select the cylinder, add an Edit Poly modifier, go to Face selection mode and set the ID for all faces to 1 for example. Then, select only the face pointing in the back direction and set its ID to 2.
Specify the Polygon ID for emission to be 2 at the bottom of the Phoenix Liquid Source parameters panel.


Hope this helps!

Thanks Slavina,

At the moment I'm running new simulation with decreased values for birth treshold. The problem is that there was too much foam at slow speeds with earlier settings. I made the simulation in a way that the speed is accelerated. The ride depth and angle are known and animated accordingly at each speed so it's easy to render stills at any speed. However when reaching the high speeds over 50 knots, there's very low amount of foam in simulation.

What comes to additional liquid source for the drive units, I'm sure, I did it in a way You suggested above.

[slavina.nikolova]

Do the faces of the emitters have the same Polygon ID number as the one You have added in the Source? I did a quick test here and it seems to work. It is important that You have the same ID assigned to the Edit Poly and in the Source ID tab.

Note that Foam simulation must be enabled from the Simulator so this type of particles can be emitted from the Source.

You could check if Foam particles are created during the simulation in the Cache File Content window, and if so, You can check if the Particle Preview is enabled and the Foam particles are visible in the viewport.

In addition: If the Detail Reduction is too high, the Foam particles might not be visible in the viewport.



Hope this helps!

[JuhaHo]

Here's a close up. Please note, the emitter surface is not flat. I wanted to spread the stream a bit.

Also I attached the cache file content screenshot.

[slavina.nikolova]

Are these Foam particles generated by the Emitters? Do you see any Foam particles in the viewport? Can you show us a screenshot of the Preview rollout?

[JuhaHo]

The foam is generated by boat hull, not by emitters.

[slavina.nikolova]

Are the emitters closed geometries? You can check it with 3dsMax STL Check modifier. Geometries with a hole or other errors might cause problems when simulating.


Thanks!

[slavina.nikolova]

Also, can you tell me which is Your exact Phoenix Version? In order to find out the exact Phoenix version you can check the About info window: 3ds Max → Top 3ds Max Phoenix FD Menu → About Phoenix.


Thanks!