Fluid simulation

Position based dynamic(PBD), SPH, Physics-based fluid simulation in Unity

2D PBD Cloth implemented in CPU

3D PBD Water using GPGPU to optimize

Intro to PBD algorithm

Overall structure

1. Simulation (Eg. Use gravity only)

v += gt

x += vt

2. PBD

Projection() depends on the specific constraint

new x = Constrain(x)

Update velocity and position

v += (new x - x)/dt

x = new x

For Cloth (Jacobi solution)

Projection/Constrain function for cloth

For Water: SPH algorithm(Based on PBD)

For every particle i
- Calculate the predicted velocity and position
  - Only apply gravity and damping, assume mass = 1
    - v += (Gravity - Damping)*dt
    - pos += v*dt
Compute the neighborhood set.
Using the neighborhood, compute density -> pressure as a constraint.