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Real-Time Fluid Simulator — Navier-Stokes Grid Solver in Your Browser

Interact with a real-time grid-based fluid simulation solving the Navier-Stokes equations — the same equations that govern real fluid flow — with adjustable viscosity and diffusion, coloured dye emitters to visualise flow, vector overlays showing the velocity field, and custom solid boundaries you can draw to redirect the flow.

How to use Real-time Fluid Dynamics Sandbox

  1. Add dye emitters and draw solid boundaries.
  2. Adjust viscosity and diffusion parameters.
  3. Interact with the fluid directly by dragging.
  4. Toggle the velocity vector overlay to see the underlying flow field.

Frequently asked questions

Is this a real physics solver or a visual effect?
A real grid-based numerical solver for the Navier-Stokes equations — the same underlying method (a semi-Lagrangian or similar stable fluid solver) used in physics and graphics research, not a pre-baked particle effect.
What do viscosity and diffusion actually change?
Viscosity controls how much the fluid resists flowing (higher values behave more like honey than water); diffusion controls how quickly dye spreads through the fluid independent of the flow itself.
Why does the simulation run on a grid instead of particles?
Grid-based Eulerian solvers are well-suited to real-time interactive fluid simulation and are what this uses; particle-based (SPH) methods are a different valid approach with different trade-offs.

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