Fully Coupled

Multi-phase / unsaturated setups

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Fully Coupled (Unsaturated / Multi-Phase) Formulation

Use when saturation changes, suction, or air phase pressure are essential to the outcome.

Checklist

• Initial saturation / pressures are consistent with boundary conditions.
• Time stepping and nonlinear tolerances are conservative at first.
• Track mass balance-like invariants where possible.

What to compare in early verification

• Saturation trends and stability (no oscillatory artifacts).
• Convergence behavior vs time step.