Smoke solver

[blackchicken]

Hello

I was waitng for this moment almost 10 years finaly, now is the right time. I always love, and watching all kinds of volumetric effects and quietly envy beatiful and robust systems not only there on odforce, but have never time and my work goes on different way. In small productions you need learn a lot of things, from modeling, lighting, realistic rendering some rigging ....Fluid simulation is really small peace of complex bussines. But, now a have time to enter into fantastic world of volume fluids. First idea is complete understanding of basic houdini smoke container. So there is my first try. So far some basic settings. Adding vorticles, gas dissipate (which i found is changing little from low-Hi sim with Up-Res setup) and source from changing volume in SOPs by ISO surface. Next step is autoresize, understanding volume velocity for more interesting source and ofcource cusom fields, from particles objects.....

http://www.youtube.com/watch?v=vhoKQdh9A5s

I have a couple of noob fluids questions:

1, Density

I need more dense fluid, I found that smoke/guides/density/smokeDensity works good for me, but when I cache sim and import in sops, density was very poor. So visualisation is only for visualisation, it is better to leave it at 1 as is for real numbers, right? But how I can do a very dense smoke? I thought that apply source will help me. I started to rise Emmision Source, which little helps but from some point not. When I add a volume ramp or volume mix for add density to cached files in sops, for better visibility, time for Hi calculatin frame is really big. What is a setup? Is there some microsolver for this things? Or it is all in shader like Basic smoke. Cloud density takes data from volume and you can manage it as you want?

2, Lifespan

I look at some cool files there on odforce and found that gasdissipate is the best way to control fluid lifespan. Another sollution is Gas Diffuse for density and velocity but this smooth things out. Fluid details vs Divisions is biggest well known problem. But what if I want smoke without dissipate, like live forever? Cold or poison smoke? Which parameter or microsolver control this? If it is conected with temperature, how a could do very hot smoke live forever?

3, In my test, there is visible, in couple of first frames, really blotchy smoke, but resolution for low res is 5 10 5 and 120 div whitch is much more better resolution then visible boxes on fist frames. Am I missing something?

Ok this is all what I have in my mind for now Any explanation will help. Thanks guys.

[blackchicken]

hello guys

I have little problem with custom velocity field. It is mainly customized file build from scratch from BUNKERs tornado scene.I use particles to create custom field which I mixing in DOPs in gas custom Vop, but when my particles die on frame 30, simulation stops. Looks like all velocity dissapear and container set size to zero. Ill send you file later, there is flip. Any idea without file?

thanks a lot....BC....

[blackchicken]

Ok so there is some tests I did with smoke solver.

1,simple RBD with static smoke, no temperature. Coins have temperature 15.

2, animate velocity and fast gas dissipate

[blackchicken]

3, just one simulation (should be much much detailed for simulating time that take, but still learning) and 7 instances.

4, 18 instances of same simulation. Im pretty happy with render times. In some frames it is visible flickering from lights but I use only 1024 depth matp with 2 samp. Render time 720p is 4 min frame. Pretty cool.

I search there on odforce and SIDEfx forum but I found that it is impossible retime simulation per instance point. I try time shift with parameter for offset set on object level and there use pointinstance() but that does not work )-: I want translate for farms only one simulation with random instance retimes but as I found, it is impossible

Edited February 3, 2012 by blackchicken

[blackchicken]

Ok so, there is a problem which I have now. i use particles converted "v" with volumefromattrib into volume and use it in RBD. There is sopvectorfield and Gas field VOP. There is my setup.

vimeo:

Thanks for help and great example files there on odforce, really cool stuff.

Edited February 3, 2012 by blackchicken

[blackchicken]

Another tests, waterfall

[chumbuk]

Very nice developing tests, thanks! It would be great to make a set of video test, reflecting the effects of key parameters, pyro and flip systems. I've been thinking about this, it would be very helpful.

Edited February 6, 2012 by chumbuk

[anthony]

Hi BC,

These are some really great tests. I'm trying to get the dissipate microsolver in H12 to work but for some reason, it isn't. Do you mind describing how you were able to get the smoke to dissipate so nicely and quickly?

To be specific, I have a rbd animating through a cloud of smoke and I want the smoke to dissipate once the object goes through it.

Thanks so much, in advance.

[dark_cry]

Another tests, waterfall

Hey Jan, i'm trying the same effect just for test, please can you describe the workflow how to approach this kind of waterfall effect? I would really appreciate man.