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The viscous contribution to the total stress is

2 \nu D_{ij}


D_{ij} = 0.5 ( \frac{\partial v_i}{\partial x_j} +
\frac{\partial v_j}{\partial x_i} )

and divergence is neglected since we only model slightly compressible flows.

Viscous heat generation

The viscous energy loss is turned into heat rate per unit volume $q$:

q = 2 \nu D_{ij} D_{ij}

See group_materi_viscosity_heatgeneration.

tochnog 2001-09-02