12.7.7 Modeling the Dissipation Rate

The dissipation tensor, , is modeled as

 (12.7-30)

where is an additional "dilatation dissipation'' term according to the model by Sarkar [ 315]. The turbulent Mach number in this term is defined as
 (12.7-31)

where ( ) is the speed of sound. This compressibility modification always takes effect when the compressible form of the ideal gas law is used.

The scalar dissipation rate, , is computed with a model transport equation similar to that used in the standard - model:
 (12.7-32)

where , , , is evaluated as a function of the local flow direction relative to the gravitational vector, as described in Section  12.4.5, and is a user-defined source term.

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