Fluid Sim - Air blast into water tank

Hi everyone,

I want to simulate an air blast into a water tank. Can this be done using Blender fluids? If so, how would I go about it? It’s different from dropping an object into water, as air is not a solid object. So would it be more like mixing two liquids of different viscosity?

Any ideas greatly appreciated!


An interesting problem …

There are 2 fluid sims in Blender. The LBM fluid simulator {from the physics tab} and the SPH fluid particles {from the particle tab for particle physics}

The LBM does not handle multiple fluids.
The SPH one can do 2 different fluids.

I have never tried to use the SPH one for non-mixing fluids, but I expect it will be difficult to get the settings right for having one set of ‘air particles’ inject themselves into a tank of ‘water particles’.

I approach I would use would be to use the LBM to make a jet of water exit a pipe and them fall up {negative gravity or upside down modelling} and be eliminated by an invisible outflow. This will then give you something that looks like the air flowing up and away. Then composite this with another LBM simulation of a tank of water with invisible objects moving in much the same trajectory as the air to create disturbances on the surface of the tank.

Hope this helps,


Thank you for your reply!

I’ll keep playing around with it. But for a start I have a potentially stupid question: how can I create a tank that is pre-filled with SPH particles (like, in the LBM simulator, you would simply use a box and declare it a fluid)? So far I only found out how to use particle emitters.

No problem, I had some fun trying to create a nice render.

Which is half the idea, since it has the air bubbles, but it needs to have a roiling surface.

Particles have to be emitted somehow … so I think you will need to do a SPH simulation in 2 stages.
First emit particles to fill the tank, let the system reach stable state, then inject the air particles.

Best regards