8.4 Viscosity

ANSYS FLUENT provides several options for definition of the fluid viscosity:

• constant viscosity

• temperature dependent and/or composition dependent viscosity

• kinetic theory

• non-Newtonian viscosity

• user-defined function

Each of these input options and the governing physical models are detailed in this section. (User-defined functions are described in the separate UDF Manual). In all cases, define the Viscosity in the Create/Edit Materials dialog box.

Materials

Viscosities are input as dynamic viscosity ( $\mu$) in units of kg/m-s in SI units or lb $_m$/ft-s in British units. ANSYS FLUENT does not ask for input of the kinematic viscosity ( $\nu$).