Exhaust

[edgem]

Hi everyone,

 

I would like to create an exhaust effect from an engine but I don't know where to start. Any ideas are welcome.

 

The engines are moving at quite a fast speed so I am wondering. Is it better to start with particles and emit from that or directly emit smoke ? Then I would probably have to increase substep tremendously so I don't think that's a good solution... How would you proceed ? 

 

 

Thanks

Edited March 22, 2016 by edgem

[fathom]

if the exhaust doesn't last long, then attach it to the engine and sim in "engine space" with some kind of wind force to drive it backwards at the right speed....

[edgem]

Actually there are multiple exhausts (around 10) so I guess I have to make one sim and duplicate it ? It last quite long (around 50 frames). What do you mean by "engine space" ?

 

I have tried simming particles first because as expectedI need lot of substep for the fluid to follow...

 

I have some reference of what  I want to do. Basically lot of fire at ignition and smoke. I'd like to create the same effect except I have multiple exhausts.

 

 

Thanks for your reply

Edited March 23, 2016 by edgem

[fathom]

ah, you mean like a rocket engine... i was thinking more like a car... so then, ignore the engine space thing...

 

depending on how far each exhaust point is, you may or may not want to sim in a single container.  if they interact, then a single container makes more sense unless it's just too large.

 

so regarding a fast moving source, what you can do is scatter your source along its motion vector.  so imagine instead of a sphere shape source, you stretch it to be a tube with rounded ends.  to do that, you need the velocity of the engine (trail sop).  take your source volume, scatter points it, then offset each point by some portion of the velocity (see below).  then convert that back to a volume (vdb from particles -- output density and include the point velocity and call it "vel").  that is now your source.

 

to do the point adjustment along the vector put this in a point wrangle:

v@P -= v@v * f@TimeInc * float(rand(i@ptnum/5.667));

Edited March 23, 2016 by fathom

[edgem]

Thanks working like a charm. I manage to create a good particle sim. Now I am struggling with creating the look of the fluid. I can't seem to get fire at the tip of the exhaust. The fire always seem to emit at the start then die quickly. I would like to keep emitting fire continuously. Any tips ?

 

The fire in my sim is emitting at high temperature. I always seem to get high temperature only at the beginning.

 

Maybe this picture below is a good example of what I want to achieve. Basically fire and then smoke.

Edited March 23, 2016 by edgem

[fathom]

are you using pyro and combustion for the smoke or are you adding density directly into your solver?

 

for what you're doing, i would opt for adding density directly.  then you'd just need to add temperature directly as well in the same volume source.  or you could add a light to illuminate your smoke from inside the engine... that might give you the result you need without having explicit "fire" via temperature volumes.

[edgem]

I am using pyro and combustion for the smoke and by sourcing my particles with a fluid source.

 

How would you add density directly ? Sorry I am still new to that pyro stuff....

 

 

I can manage to get fire emitting continuously with still emitter but with a fast moving particles, it would just stop emitting. I noticed that the temperature, fuel and heat channel cools down. Is there any way to keep the these always high and constant during the animation ?

 

Thanks

Edited March 24, 2016 by edgem

[fathom]

okay, so when you say the fire stops, the smoke stops as well, right?

 

are you doing a dynamic resize on the sim?  could be your source particles are not being captured by the sim.  if this is the case, you can up the padding on the gas resize fluid dynamic dop.

 

 

you can add density directly with a volume source dop.

Edited March 24, 2016 by fathom