Use the Convection and Diffusion node to define the fluid properties, velocity, diffusion coefficient, and dispersion model. This node is present by default.

The default Density ρ (SI unit: kg/m3) is User defined and is 1 × 103 kg/m3.

Enter a value or expression for the Yield stress τs (SI unit: Pa) and Plastic viscosity μs (SI unit: Pa·s). The defaults are 0 Pa and 0 Pa·s, respectively.

No user selection is required for the Tangential velocity u.

Enter a value or expression for the diffusion coefficient Dc (SI unit: m2/s). The default is 1 × 10-9 m2/s.

Select a Dispersion model — User defined (the default) or Fan (laminar, circular cross section). For User defined, enter a value or expression for the Dispersion coefficient DD (SI unit: m2/s). The default is 0. For detailed information about dispersion, see the theory section Dispersion.