Ansys Fluent can solve the transport equation for an arbitrary, user-defined scalar (UDS) in the same way that it solves the transport equation for a scalar such as species mass fraction. Extra scalar transport equations may be needed in certain types of combustion applications or for example in plasma-enhanced surface reaction modeling.

This section provides information on how you can specify user-defined scalar (UDS) transport equations to enhance the standard features of Ansys Fluent. Ansys Fluent allows you to define additional scalar transport equations in your model in the User-Defined Scalars Dialog Box. For more information about setting up user-defined scalar transport equations in Ansys Fluent, see User-Defined Scalar (UDS) Transport Equations in the User's Guide.