The sub-dictionary ddtSchemes defines a temporal discretization. The cases are solved as steady state problems:

ddtSchemes
{
    default         steadyState;
}

In file fvSchemes the important sub-dictionary is divSchemes. The following second order setup of divergence schemes is recommended:

divSchemes
{
    default          none;
    
    div(phi,U)       bounded Gauss limitedLinear 1.0;
    div(phi,k)       bounded Gauss upwind;
    div(phi,omega)   bounded Gauss upwind;
    div(phi,epsilon) bounded Gauss upwind;
    
    div((nuEff*dev(T(grad(U))))) Gauss linear;
}

For complicated unstable case, an alternative may be first order setup of divergence schemes:

divSchemes
{
    default          none;
    
    div(phi,U)       bounded Gauss upwind;
    div(phi,k)       bounded Gauss upwind;
    div(phi,omega)   bounded Gauss upwind;
    div(phi,epsilon) bounded Gauss upwind;
    
    div((nuEff*dev(T(grad(U))))) Gauss linear;
}