puff of smoke from a box

[cspears2002]

Hi,

I'm trying to create a puff of smoke that comes out of an animated box. I parented a sphere to a box object with the top removed. The sphere is the smoke source. I added the box to the DOP network as a passive RBD object. However, the smoke still flows through the box's walls. Plus, the RBD object seems to be blocking the smoke somehow, which is strange because I turned off volume based collision detection. What am I doing wrong?

[RontheDon]

Hi Christopher,

should be fairly simple to achieve

There is only a few things to look out for:

- box needs some sort of "thickness" => i.e. polyExtrude

- ur "static" RBD needs to have "use deforming Geometry" enabled (also try and avoid animating geo on SceneLevel whilst using DOPs)

- same goes for your smoke source object

- fluid container needs to be big enough to contain produced smoke at all times

that should be it.

cheers

[cspears2002]

Hey,

I took RontheDon's advice and have met with some success! Unfortunately, I still get some smoke leaking through my box! I cranked the divisions under the Collision/Volume tabs for my RBD Object up to 70, but I still get some leakage. Plus, when I crank up the divisions, my sim takes longer to cook. Any advice?

Thanks.

Hi Christopher,

should be fairly simple to achieve

There is only a few things to look out for:

- box needs some sort of "thickness" => i.e. polyExtrude

- ur "static" RBD needs to have "use deforming Geometry" enabled (also try and avoid animating geo on SceneLevel whilst using DOPs)

- same goes for your smoke source object

- fluid container needs to be big enough to contain produced smoke at all times

that should be it.

cheers

marc_smoke_pump_v05.hipnc

[RontheDon]

Hey Christopher,

I still get some smoke leaking through my box!

This is due to the thickness of the box wall on the bottom.

If you look at your result of the cookie u are using to create ur box in wireframe, you will notice, that the sides are a lot thicker then the bottom.

Generally speaking the smaller (and therefore also thinner) an object is the higher res the sampling grid needs to be to sample it accurately.

=> to keep the divisions lower adjust the box thickness of the RBD object

Plus, when I crank up the divisions, my sim takes longer to cook

This is normal, as more data needs to be processed, however you can majorly speed up DOPS by caching out your collision object to disc.

Hope this helps

cheers

[cspears2002]

I made the walls thicker and that didn't work. I increased the divisions in the collision geometry up to 100, and that didn't work either. I adjusted the sub steps on the AutoDopNetwork. When that didn't work, I played with the sub steps on the RBD Solver and the Pyro Solver. Not sure what I am doing wrong...

marc_smoke_pump_v07.hipnc

[Nibbler]

cspears2002: I think density penetrates box because of how you made it using cookie in sops, if you add a point sop with normals you'll see the normals on the wrong side of geometry

Edited May 13, 2010 by Nibbler

[RontheDon]

cspears2002: I think density penetrates box because of how you made it using cookie in sops, if you add a point sop with normals you'll see the normals on the wrong side of geometry

good point, I didn't check on the normals. All I could see in the old file was that the collision geometry wasn't detailed enough

hope the normals worked.

cheers