30.16. Mixing Index

The mixing index is defined as  [39]

(30–10)

where is the equivalent shear rate defined as

(30–11)

and is the magnitude of the vorticity vector. For a shear flow, the mixing index is equal to 0.5, whereas its value is 1 in a purely elongational flow.

In a purely rotational flow, the mixing index is zero. The mixing index is not defined everywhere in the flow problem; singular values arise in regions where the denominator is zero (for example, along the axis of symmetry of a Poiseuille flow).

The mixing index will appear as a scalar in your graphical postprocessing program. The procedure for specifying the calculation of the mixing index is as follows:

  1. Create a new sub-task.

      Create a sub-task

    1. Select Postprocessor as the sub-task type.

        Postprocessor

    2. When prompted, enter a name for the postprocessor sub-task.

  2. In the F.E.M. Task Postprocessor menu, select Mixing Index.

      Mixing Index

    Ansys Polydata will tell you where the calculation will be performed. You can click OK to continue.

    No additional parameters or boundary conditions are required.