Passive Scalars

A passive scalar is a quantity that is transported by the fluid but does not alter the fluid's behavior. To configure the code to evolve one or more species of passive scalars, run the configure.py script with --nscalars=N. This will set the internal preprocessor macro NSCALARS to N. See Configuring page for more details.

When NSCALARS > 0, the Outputs that specify either cons or prim variables will automatically include the conservative or primitive formulation of each passive scalar species, respectively.

Diffusion Processes are also supported for the passive scalars, and can be activated by setting a positive problem/nu_scalar_iso value in The Input File or when Overriding Input Parameters.