VirtualTimeStepSize

The virtual time step size helps to control the correction pressure. We choose \begin{align} \Delta t_{virt} = \min \left( \Delta t , A_{virt} \frac{\rho h^2}{\hat{\eta}} \right)\end{align} The term \( A_{virt}\) is represented by the input parameter COEFF_dt_virt . The actually used value of \( \Delta t_{virt}\) can be retrieved by the variable %ind_dt_virt% . A universal number is \( A_{virt} = 1\) . In case of vp- , one can try to make \( A_{virt}\) as small as possible, in order to force \( \nabla^T {\bf v}\) as close to the target value as possible. In case of v-- together with small local \( Re\) numbers, choosing \( A_{virt} > 1\) is favorable in order to avoid oscillations of the correction pressure.