# Navier Stokes Solver
# Tolerance (absolute) of the Navier-Stokes solver
This is the convergence criterion for all the nonlinear residuals of the Navier-Stokes equations. The nonlinear iterations through pseudo-time steps only complete when:
- all the convergence criteria are satisfied, including this,
- or when the maximum number of nonlinear iterations are reached.
# Number of linear iterations within each Navier-Stokes nonlinear iteration
Each nonlinear (quasi-Newton) iteration requires solving a system of linear equations, for which we use an iterative method. This parameter specifies how many linear iterations to use when solving the system of linear equations iteratively.
# Kappa parameter in the MUSCL scheme for the Navier-Stokes solver
Specify a number between -1 and 0.333. -1 is more robust and 0.333 is the least dissipative.
# Order of accuracy for spatial discretization of the Navier-Stokes solver
This order of accuracy is referred to the spatial discretization schemes for the Navier-Stokes equations convection terms. Specify either 1 for first-order or 2 for second-order. You should use second-order solver for an accurate flow solution. But sometimes first-order solutions are useful as initial conditions for cases that are difficult to converge.