Solution method

The finite element models generated in numgeo are usually non-linear. The primary solution variables are in most cases the displacements of the solid \(\boldsymbol{u}^s\) and the pore water pressure \(p^w\), but can also include the pore air pressure \(p^a\) or the pore water displacement \(\boldsymbol{u}^w\). How these variables change is governed by equilibrium equations. The methods implemented in numgeo to solve these equations are discussed in the following sections:

• Newton-Raphson method
• Convergence criteria
• Initial solution increment
• Automatic time stepping