# Time
- backward: transient second order
- bounded
- CoEuler
- CrankNicolson: transient second order
- uses a blending factor $\psi$
- $\psi = 0$ --> pure Euler
- $\psi =1$ --> pure Crank-Nicolson
- Euler: transient first order, bounded
- localEuler
- SLTS
- steadyState: steady simulations (simpleFoam)
# Convective Terms
- upwind: first order
- linearUpwind: second order, bounded
- linearUpwindV: second order, bounded, for vector fields
- linear: second order, unbounded
- limitedLinear: second order, bounded, more stable than linear
- recommended for LES
# Gradient Terms
- edgeCellsLeastSquares
- fourth
- Gauss
- leastSquares
- pointCellsLeastSquares
Syntax:
$\text{grad(U)}\quad\text{Gauss}\quad\text{linear};$
# Laplacian Terms
- corrected
- for meshes with grading and non-orthogonality
- faceCorrected
- limited
- linearFit
- orthogonal
- mainly limited to perfect hex meshes with no grading
- quadraticFit
- uncorrected
- for meshes with very low non-orthogonality
- more diffusive than limited and corrected
# Recommended Setup
```c++
ddtSchemes
{
default CrankNicolson 0;
}
gradSchemes
{
default cellLimited Gauss linear 0.5;
grad(U) cellLimited Gauss linear 1;
}
divSchemes
{
default none;
div(phi,U) Gauss linearUpwindV grad(U);
div(phi,omega) Gauss linearUpwind default;
div(phi,k) Gauss linearUpwind default;
div((nuEff*dev(T(grad(U))))) Gauss linear;
}
laplacianSchemes
{
default Gauss linear limited 1;
}
interpolationSchemes
{
default linear;
}
snGradSchemes
{
default limited 1;
}
```
- Very similar to setup of commercial solvers
- Second order accurate, fully bounded
- Should change blending factor of **laplacianSchemes** and **snGradSchemes** based on mesh quality
- Use a CFL number < 2 to minimize time diffusion