Fluid simulation solves the Navier-Stokes equations, the physics of liquids and gases, on a grid each frame: velocities advect, pressure equalizes, vortices curl. Jos Stam’s 1999 stable fluids method made it real-time; GPUs made it high resolution.
The result moves like nothing faked: ink blooms, smoke shears, stirring leaves eddies that persist and interact. Audiences read the physics instantly because everything real behaves this way.
The cost is control: simulations are steered, not posed. Audio input works as forces (a kick as an impulse into the velocity field) which is exactly how Photism’s fluid scene runs, real Navier-Stokes stirred by the music.