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heydabop
I decided to try something like Computational Fluid Dynamics in Houdini using the smoke solver. Obviously the output data will not be used for prototyping or anything, but it looks cool. I've got some draft screenshots up on flickr.

http://www.flickr.com/photos/heydabop/sets/72157622551197396/ [flickr.com]

And of course, I'm open to any comments, even criticisms.
phtj
I am very interested in this - using houdini for ‘rough’ CFD analysis. In our case, we are interested in ventilation in buildings. I am wondering what level of accuracy could be expected - i.e. could houdini's pyro be used to better understand airflow in buildings.
heydabop
phtj
I am very interested in this - using houdini for ‘rough’ CFD analysis. In our case, we are interested in ventilation in buildings. I am wondering what level of accuracy could be expected - i.e. could houdini's pyro be used to better understand airflow in buildings.

Well, I don't really know how accurate it is, probably not greatly accurate, as it's normally used for movie effects as opposed to technical prototyping. But perhaps someone else can shed some light on the subject. I just did it because I like how it looks.
probbins
Well houdini isn't an engineering tool, however companies are starting to use it for just this sort of simulation.
It provides a faithful representation of a fluid solution, and is excellent for rapid prototyping the setup you want to inject into your mainframe simulator.
heydabop
probbins
Well houdini isn't an engineering tool, however companies are starting to use it for just this sort of simulation.
It provides a faithful representation of a fluid solution, and is excellent for rapid prototyping the setup you want to inject into your mainframe simulator.

Ah, okay cool. Thanks for shedding some light on the subject.
vigneshkaushik
Hi heydabop,

I know its been 5 years since, but would you pls share your .hip files if you still have them. It would be very useful to understand how it is done. Thanks.
old_school
Simple to set up a fairly accurate smoke sim these days. All you need is a smoke tank set up as a wind tunnel and evaluate just the velocity against your colliders.

For accuracy, it's best to use the PCG Projection method. It's slower than Multigrid but it is more accurate.

After that it is all about constructing your collision geometry. It's probably easiest to add an RBD passive object to the scene rather than pump in colliders.

By default when you add an empty smoke container to start the set-up, it sets the Smoke Object DOP's Velocity Sampling to Faces which is the more accurate method. Note that some of the preset pyro tools may move this off the default of Faces.

Because you are solving just for the velocity, you can strip out most of the fields. Just keep vel, pressure, confinement, collision and collisionvel in the Smoke Object DOP.

Now crank up the resolution and sim.

The default Smoke Solver has no shaping micro-solvers in it. No turbulence, shredding, etc. You might want to add the Gas Vortex Confinement DOP to add confinement to the simulation.

It would be trivial to add tools to inspect the velocity field to see what the speed is in various parts of the scene.

See the attached file.
vigneshkaushik
Thanks a lot Jeff. Thats fantastic. I have been exploring smoke and pyro DOPs for the past few days but got nothing quite as close to what you have shown. I will have a look at the file attached and will post further questions which I may have.
mogul4200
I would be very interested in a tool that would inspect the simulation. Most particular would be a tool to report velocity at a point like the cursor as you move it around.

Thanks
boya_wangca34e169c5bc427a
Thanks Jeff! Thanks for sharing the file and it really helped a lot!
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