34.3.23 Define/User-Defined/Scalars...

The Define/User-Defined/Scalars... menu item opens the User-Defined Scalars dialog box.

User-Defined Scalars Dialog Box

The User-Defined Scalars dialog box allows you to include user-defined scalar transport equations in your calculation. See Section  9.1 for details.

Controls

Number of User-Defined Scalars   specifies how many additional scalar transport equations you would like to include in the calculation.

Inlet Diffusion   when enabled allows you to include the diffusion term in the UDS transport equation for all inflow and outflow boundaries.

User-Defined Scalars Options   contains settings that define the scalar transport equation.

UDS Index   when set to $0$ marks the first user-defined scalar equation.

Solution Zones   specifies in which zone the scalar equation will be solved: all fluid zones, all solid zones, all zones (fluid and solid) or selected zones.

Flux Function   is a drop-down list containing available functions for the convection term of the user-defined scalar transport equation(s).

none   (the default) indicates that there is no convection term included in the scalar transport equation(s); i.e., you want to solve a Poisson equation instead of a convection/diffusion equation.

mass flow rate   indicates that the convection term in the scalar transport equation(s) is equal to the mass flow rate $\rho \vec{v} \cdot \vec{A}$.

Note that the none and mass flow rate options will apply to all solved user-defined scalars. A user-defined flux function must be supplied if a different convective flux is desired for each user-defined scalar.

Unsteady Function   is a drop-down list containing available functions for the unsteady term of the user-defined scalar transport equation(s).