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Next: 9.3.7 Quasi-hydrostatic assumption Up: 9.3 The stress tensor Previous: 9.3.5 Trace-free frictional stress

9.3.6 Summary of the frictional stress tensor

In summary, the viscous stress tensor is given by

\begin{displaymath}\tau^{mn} =
\rho \,
\left(
\begin{array}{ccc}
e_{11} \, ...
...c^{44}
&
e_{33} \, (c^{33} - c^{13} )
\end{array} \right).
\end{displaymath} (9.46)

Motivated by Wajsowicz (1993) and Smagorinsky (1993), define the kinematic viscosity coefficients
$\displaystyle \nu$ = $\displaystyle 3 \alpha = (c^{11} + c^{12})/2 - c^{13},$ (9.47)
A = $\displaystyle \beta = (c^{11} - c^{12})/2$ (9.48)
$\displaystyle \kappa$ = $\displaystyle \gamma = c^{44}/2,$ (9.49)

where $\nu, A, \kappa$ is the notation used in Wajsowicz (1993), and $\alpha, \beta, \gamma$ is the notation used in Smagorinsky (1993). The stress tensor components now take the form

\begin{displaymath}\tau^{mn} =
\rho \,
\left(
\begin{array}{ccc}
(A + \nu) ...
... \kappa \, e_{23}
&
2 \, \nu \, e_{33}
\end{array} \right)
\end{displaymath} (9.50)

which exposes a total of three viscous degrees of freedom.



RC Pacanowski and SM Griffies, GFDL, Jan 2000