Simulating backdraft

Hi there,
I work for a company which makes virtual training software for firefighters.
I’m trying out Embergen and see a lot of value.
But as Embergen in VFX focused, I wonder about some of the simulation possibilities/controls.
Especially I am looking to simulate a backdraft which occurs when a fire in a closed room reaches very high temperatures and exhousts the amount of oxygen. When a door is opened, air rushes in, supplies the required oxygen and the result is a huge explosion.
As famously demonstrated here by the slomoguys

I am confident that simulating the explosive bit isn’t a problem.
But I haven’t seen any controls for the amount of oxygen in the simulation. So I’m not sure how I would achieve the air rushing into the room bit.
Are there oxygen or pressure controls that I have overlooked ?
If someone can point me in the right direction, please tell me, I still have 1.5 week on my trial.

Thanks in advance,

Hey Patrick,

You might want to look at our shed explosion preset as it has an explosion similar to this backdraft. Overall though, you’re not going to get super accurate results to things like this as our goal is to simulate pretty things, not specifically accurate things.

The other thing i’d wonder is how you’re going to get this into your training program as in the end it’d just be a flipbook on a sprite. We do have an oxygen control option in our combustion settings, but I’m not sure if it works. Our combustion needs an overhaul.


Hi Nick,
I totally understand that I’m not your target audience

Yep, that shed looks like a nice start, but I’ll need to change a number of things to get the effect that I’m after.
Thanks for the oxygen pointer! So I guess the oxygen in fuel setting is global for the whole simulation, and it can be animated. This could work :slight_smile:

Can I set the pressure inside of a shape maybe ? Something that wouldsllow me to manipulate the flow of the smoke when the door opens and the air rushes in.
(faling that, I could maybe build something like an invisible seringe-like shape to suck air away)
Also, can smoke be fuel that hasn’t ignited yet ?

Regarding exporting to Unity, I found this repo, but it’s pretty stale and I haven’t gotten it to work yet.

Another idea is to create flipbooks of slices of the explosion and display them on planes.
Nice idea, but to capture that would require configurability of the near/far clip planes of the camera and those are not exposed. (and preferably an ortho camera)

Ciao, Patrick

Today I went to a museum and saw the slice/plane concept showcased in all it’s analog glory :smiley:

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