Consistent Stabilization
This section contains two consistent stabilization methods: streamline diffusion and crosswind diffusion. These are consistent stabilization methods, which means that they do not perturb the original transport equation.
The consistent stabilization methods are active by default. A stabilization method is active when the corresponding checkbox is selected.
Streamline Diffusion
Streamline diffusion is active by default and should remain active for optimal performance for heat transfer in fluids or other applications that include a convective or translational term.
Crosswind Diffusion
Streamline diffusion introduces artificial diffusion in the streamline direction. This is often enough to obtain a smooth numerical solution provided that the exact solution of the heat equation does not contain any discontinuities. At sharp gradients, however, undershoots and overshoots can occur in the numerical solution. Crosswind diffusion addresses these spurious oscillations by adding diffusion orthogonal to the streamline direction — that is, in the crosswind direction.
Stabilization time scales
For time-dependent problems, a time scale is introduced in the consistent stabilization terms. A simple approach is to set the time scale to the time step Δt from the solver, however this method is not representative of the actual physics. When the Use dynamic subgrid time scale option is activated, the time scale is calculated from projections of the weak expressions.