Example Maya scene of gasoline explosion

[dgould]

I've been able to create a basic explosion but not got it moving or looking as good as Ivaylo's video of a gasoline explosion:

http://www.youtube.com/watch?v=XsmSYS4GnZY&list=UUe748BJk1LTPRMxUHqd0YOQ& index=12

Could you point me a Maya scene that produces this video or something similar?

Thanks.

[Ivaylo Katev]

Hi, This video was made by a coworker named Ivelin , but unfortunately it was just a test and the scene was not kept. As i remember, it was fuel based, and sow moving advection was used. We will try to reproduce it and make tutorial about such kind of explosions.

[dgould]

Any progress on the example scene? Needing to get several shots completed and the example scene would help immensely.
Thanks.

[Ivaylo Katev]

yes, we found the max scene, and yesterday it was converted into maya scene, just some minor details are remaining

[dgould]

Fantastic! Thanks guys.

[wxyz]

Would love to get the Max scene.

[Ivaylo Katev]

max and maya scenes, enjoy

[wxyz]

Thanks, much appreciated

[dgould]

When I run the simulation and then play it back the result is repeated over two frames. For example the simulation looks the same at frame 21 and 22. It then changes at frame 23 but stays the same again at frame 24.

How can I get the simulation to update every frame rather than every second frame?

[Ivaylo Katev]

if you are running nightly build, this may be because we are digging in the frame loading right now.

[dgould]

I'm running the stable build "Phoenix FD for Maya 2013, version 2.0.0 from Feb 14 2013, 04:07:58"

I think the problem is isolated to the Gasoline Example Scene you sent.

I started a new scene and created a basic fire and the sim updates each frame as you'd expect.

[Ivaylo Katev]

ok, we have to look what it can be

[ivaylo.ivanov]

Can't reproduce the problem here. Do you use viewport 2.0? It can bug sometimes. Also check if this is happening with GPU preview turned off. And one more question - what video card do you use?

[dgould]

Thanks Ivaylo for taking a look at this. I started again and it seems that I've done something to the scene to cause this. Could you take a look at the attached scene and see if there is something obvious causing this repeated frame issue? For example, frames 20 and 21 repeat.

Gasoline Explosion_Maya_2013_V-Ray_dgRevised.ma.zip

[ivaylo.ivanov]

The problem is the SPF/Max Step combination. It's probably the most confusing part in PhoenixFD and we are currently revisiting it. We will try to simplify these settings in the service pack. The issue is the this - the fluid is moving fast, and the max advection step is limiting the movement of the fluid. SPF 0.5 means that you are doing 2 frames per step. The movement is limited at the first and the second frame with the same amount, and they look exactly the same. In other words, the second frame can't advect more of the fluid.

To prevent such pitfalls, you must not limit both the max advection step and SPF. Only one of them. And to get the best simulation speed, it's better to limit the SPF, and increase the max adv step. However the original Phoenix FD 2.0 uses the max advection step to calculate the adaptive grid box. And you will get big overhead if you do this, and it's better to disable the adaptation. Only the unstable nightlies have this issue resolved.