QUick smoke "gunshot like" simulation - help/guides appreciated

[PIXELBOX_SRO]

Hello guys,
i have a simulation that i need for a game animation were creating.
Here is a picture that will help more to understand what i need to achieve:


Basically i have a an object with a hole in its where i have the SIM SOURCE hidden.
Also in the hole is a "BULLET" that shoots up within less than 25 frames which should be closely followed by simulated smoke that needs to resemble a gunshot more or less - it can be more smoky no problem, but it needs to have some nice details although its happening quite fast.
The smoke has to disappear quite soon - at least i need to be able to make the smoke start disappearing at certain point.
The whole sim is captured within a glass object.

What would be the best approach to tackle this please?

Is it possible to simulate this lets say across 50 frames and then time warp it to make it faster? The bullet will be just an object with body force helper yes?

The guides in the documents section are all gone apart from simple liquid.
I am refering to this thread of mine here: https://forums.chaosgroup.com/showth...uick-guides-go

Thanks a lot for your help!
Best Regards

Martin

[Guest]

Hi,
this scene has more than one setups and all of them would lead to different results. It depends on what you like and experimenting with different parameters.

1. Smoke can be emitted from hidden geometry like on your drawing.
2. Smoke can be emitted from inner side of the tube (using a polygon ID)
3. Smoke can be emitted from the back side of the flying bullet. (using a polygon ID).

The output result would be different.

You can play with Motion velocity multiplier to increase smoke's motion vel.
Smoke dissipation controls how fast the smoke will dissipate.

Grid resolution, Steps per frame parameter and the smoke Discharge are crucial for the final result.

It's pointless to simulate it 50 frames and then make it faster. You can simulate it 25 frames using more SPF (steps per frame).
"The bullet will be just an object with body force helper yes?" Well, as I say depends on what you want. You can use Body Force but without it bullet will drag some smoke due to its velocity. If you choose No.3, there is no need of Body Force at all.

[PIXELBOX_SRO]

Hi George and thanks for you reply!

will try to buid this up with your recommendations in mind and see where i will get.
let you know soon i i go

cheers
M

[PIXELBOX_SRO]

Hi guys,
i ve made some significant progress but i am experientcing something i woudl call a "smoke lag"
Please notice the gap between the dice (body force) and the smoke.
The smoke is emited from a source bellow..
Any ideas?
i ve the steps per frame set to 4.

[Guest]

Hi,
If the object is moving fast (cube is going upwards, isn't it?) you need to increase steps-per-frame (SPF). Try with 10 for example and compare the results

[PIXELBOX_SRO]

Hello,
if i raise SPF it fixes the problem, but i get a lot thicker and denser solution, and completely loose the crispiness.
I need to be using the massive smoke setup but i need crispier, less dense look.
How do i achieve that please?
Cheers
M

[Guest]

Hi,
there's simple solution --> Rendering roll-out --> Volumetric options --> Smoke opacity.

Then change Simple smoke opacity value or change - Based on --> Smoke and use curve editor. With curve editor you can adjust the opacity very precisely.

Cheerz!

[PIXELBOX_SRO]

well i ve tried before i posted and wasnt too successful so i asked will play with it some more then
too bad phoenix doesnt work with IPR....woudl be easier to tweak.

[Guest]

Don't you use the GPU preview?

[PIXELBOX_SRO]

i do but the light conditions in the scene are quite complicated

[Svetlin.Nikolov]

Indeed, I'm afraid that right now you can't detach the substeps of a fast moving object from the steps per frame, so changing them would change the smoke behavior as well. We need to figure a way to change both independently...

[Svetlin.Nikolov]

If it won't impact the look too much, you could try filling the gap by making the inside or just the lower part of the object a brush source. Just a random thought ��

[PIXELBOX_SRO]

i found that using too many SPF will change the smoke behaviour to somethign that resembles more of a fire...its just way too quick

[Guest]

SPF change the fluid's behavior and that's normal. Tip: You can decrease the Time Scale or increase Scene scale or both of them to make smoke slower. Scene scale also will change its behavior.