Numerics and convergence

These pages explain how Vanellus discretizes and solves its equations and how to interpret numerical convergence.

• Numerics presets compares the coordinated solver settings behind fast, balanced, and stable.
• Field initialization and starting guesses explains the fields and coupled states used before the first SIMPLE iteration.
• Advection schemes explains the bounded first- and second-order schemes.
• Relaxation explains equation under-relaxation and the separate relaxation controls used by boundaries and couplings.
• Residuals and linear-solver convergence distinguishes inner linear convergence from SIMPLE convergence and explains residual scaling.
• Preconditioners and fallbacks explains the available right preconditioners and ordered retry behavior.

For practical instability diagnosis and numerical changes, use Troubleshooting instabilities.