SPACE // EUCLIDEAN ℝ³
TERRITORY 07 · DYNAMIC SIMULATION

Physical Simulation

The physical forces that sculpt form across time—Eulerian Navier-Stokes atmospheric smoke, SPH/FLIP ocean waves, unconditionally stable XPBD cloth, and FEM hyperelastic soft bodies.

Indexed Physical Solvers (6)

Eulerian Grids vs. Lagrangian Particles vs. XPBD Constraints
Fluid DynamicsEulerian Grid (Voxel MacCormack)

Eulerian Navier-Stokes Fluid Solver (Smoke & Gas)

The mathematical physics of volumetric atmosphere. Solves pressure Poisson equations across 3D voxel grids to simulate hyper-realistic smoke plumes, fire explosions, and swirling vortex rings.

GOVERNING PDE / CONSTRAINT FORMULATION:\frac{\partial \mathbf{u}}{\partial t} + (\mathbf{u} \cdot \nabla)\mathbf{u} = -\frac{1}{\rho}\nabla p + \nu \nabla^2 \mathbf{u} + \mathbf{f}, \quad \nabla \cdot \mathbf{u} = 0
Conservation Laws Enforced:
Mass Conservation (Incompressibility)Momentum ConservationThermal Buoyancy Advection
Stability Criteria: CFL Condition: Δt ≤ C · Δx / ||u_max|| (often bypassed via Jos Stam's Stable Fluids semi-Lagrangian advection).
Industry Solvers: Houdini Pyro FX · Blender Mantaflow · EmberGen · Axiom
Liquid & Particle HydrologyLagrangian Particles + Background Grid (FLIP/APIC)

Lagrangian Liquid Solvers (SPH, FLIP & APIC)

Simulating water droplets, ocean waves, and violent splashing. Tracks millions of moving water particles and transfers velocities to background grids for sharp, volume-preserving liquid meshing.

GOVERNING PDE / CONSTRAINT FORMULATION:\frac{D\mathbf{v}}{Dt} = -\frac{1}{\rho}\nabla P + \mathbf{g} + \frac{\mu}{\rho}\nabla^2 \mathbf{v} + \frac{\sigma}{\rho}\kappa \mathbf{n}
Conservation Laws Enforced:
Particle Volume InvarianceAngular Momentum Preservation (APIC affine velocity transfer)Surface Tension Minimization
Stability Criteria: Sub-stepped time integration based on sound speed or maximum particle velocity.
Industry Solvers: Houdini FLIP · Bifrost · RealFlow · DualSPHysics
Cloth & Membrane MechanicsConstraint Projection (XPBD)

Extended Position Based Dynamics (XPBD Cloth & Hair)

The modern standard for real-time and offline garment simulation. Directly projects vertex positions to satisfy stretching, shearing, and bending constraints without numerical blow-up.

GOVERNING PDE / CONSTRAINT FORMULATION:C_j(\mathbf{x}) = 0, \quad \Delta \mathbf{x} = -\frac{w_i}{\sum w_k + \frac{\tilde{\alpha}}{\Delta t^2}} C(\mathbf{x}) \nabla C(\mathbf{x})
Conservation Laws Enforced:
Length & Area InvarianceBending ResistanceDynamic Frictional Contact
Stability Criteria: Unconditionally stable (avoids velocity explosion; compliance α allows true physical stiffness independent of time step).
Industry Solvers: Houdini Vellum · Marvelous Designer · Unreal Chaos Cloth · Qualoth
Discrete Particle SystemsVerlet / Runge-Kutta 4

Mass-Spring & Particle Dynamics

Millions of independent point masses governed by vector force fields, turbulence, collision surfaces, and emitter rules. Perfect for rain, sparks, dust motes, and magic FX.

GOVERNING PDE / CONSTRAINT FORMULATION:m_i \frac{d^2 \mathbf{x}_i}{dt^2} = \mathbf{F}_{\text{gravity}} + \mathbf{F}_{\text{drag}} + \mathbf{F}_{\text{noise}} + \sum_{j} \mathbf{F}_{\text{spring}}(i,j)
Conservation Laws Enforced:
Newtonian MomentumKinetic Energy Dissipation
Stability Criteria: Time-step dampening to prevent spring resonance oscillation.
Industry Solvers: Houdini POPs · Unreal Niagara · Blender Particles · Thinking Particles
Rigid Body MechanicsConstraint Impulse Projection

Rigid Body Dynamics & Destruction Solvers

Calculating massive structural collapse, tumbling bricks, and vehicle crashes. Enforces hard contact constraints, friction cones, and inertia tensors across thousands of solid objects.

GOVERNING PDE / CONSTRAINT FORMULATION:M \dot{\mathbf{v}} = \mathbf{f} + \mathbf{J}^T \boldsymbol{\lambda}, \quad \mathbf{I} \dot{\boldsymbol{\omega}} + \boldsymbol{\omega} \times (\mathbf{I}\boldsymbol{\omega}) = \boldsymbol{\tau} + \mathbf{J}_{\text{rot}}^T \boldsymbol{\lambda}
Conservation Laws Enforced:
Linear MomentumAngular Momentum via Inertia Tensor INon-Penetration Signorini Conditions
Stability Criteria: Projected Gauss-Seidel iterative velocity clamping.
Industry Solvers: Houdini Bullet · PhysX / Chaos · Havok · Blender Rigid Body
Continuum Soft Body MechanicsContinuous Finite Element / Material Point (MPM)

Soft Body Mechanics (FEM & Material Point Method)

Simulating volumetric squish, flesh tearing, snow compaction, and muscle contraction. Uses continuum solid mechanics and hyperelastic strain tensors for cinema-grade organic realism.

GOVERNING PDE / CONSTRAINT FORMULATION:\nabla \cdot \boldsymbol{\sigma} + \rho \mathbf{b} = \rho \ddot{\mathbf{u}}, \quad \boldsymbol{\sigma} = \frac{1}{J} \frac{\partial \Psi}{\partial \mathbf{F}} \mathbf{F}^T
Conservation Laws Enforced:
Continuum Mass & MomentumHyperelastic Strain Energy (Neo-Hookean)Elastoplastic Yielding (Snow / Clay / Sand)
Stability Criteria: Implicit Newmark / Newton-Raphson nonlinear convergence.
Industry Solvers: Houdini FEM · Taichi MPM · Ziva VFX (Anatomy) · Carbon Scatter
2026 AEO KNOWLEDGE GRAPH & INQUIRY TREE

Frequently Explored Structural Questions

6 Verified Semantic Answers