next up previous contents
Next: 9.8.2 Zonal friction Up: 9.8 Old friction implementation Previous: 9.8 Old friction implementation

9.8.1 Spherical form of second order friction

In spherical coordinates, the metric takes the form

gij = $\displaystyle \mbox{diag} \, (g_{\lambda \lambda}, g_{\phi \phi}, g_{rr})$  
  = $\displaystyle \mbox{diag} \, (a^{2} \cos^{2}\phi, a^{2}, 1)$ (9.177)

and
$\displaystyle (\delta x, \delta y, \delta z)$ = $\displaystyle (a \cos\phi \, \delta \lambda, a \, \delta \phi, \delta r).$ (9.178)

Consequently, it is only $g_{11} = g_{\lambda \lambda}$ which has nonzero spatial dependence. The friction then can be written
  
Fx = $\displaystyle \frac{\partial (A \, D_{T})}{\partial x}
+
\frac{1}{\cos^{2}\phi}...
...ac{\partial (A \, \cos^{2}\phi \, D_{S})}{\partial y}
+ (\kappa \, u_{,z})_{,z}$ (9.179)
Fy = $\displaystyle \frac{\partial (A \, D_{S})}{\partial x}
-
\frac{1}{\cos^{2}\phi}...
...c{\partial (A \, \cos^{2}\phi \, D_{T})}{\partial y}
+ (\kappa \, v_{,z})_{,z},$ (9.180)

where
DT = $\displaystyle u_{,x} - v_{,y} - (v/a) \, \tan\phi$  
  = $\displaystyle (a \cos\phi)^{-1} \, (u_{,\lambda} - v_{,\phi} \, \cos\phi - v \, \sin\phi)$  
DS = $\displaystyle v_{,x} + \cos\phi \, (u/\cos\phi)_{,y}$  
  = $\displaystyle (a \cos\phi)^{-1} \, (v_{,\lambda} + u_{,\phi} \, \cos\phi + u \, \sin\phi).$ (9.181)

The terms
  
Fu = $\displaystyle \frac{1}{a \, \cos\phi} \, \frac{\partial (A \, D_{T})}{\partial ...
...{a \, \cos^{2}\phi}
\frac{\partial (A \, \cos^{2}\phi \, D_{S})}{\partial \phi}$ (9.182)
Fv = $\displaystyle \frac{1}{a \, \cos\phi} \, \frac{\partial (A \, D_{S})}{\partial ...
...{a \, \cos^{2}\phi}
\frac{\partial (A \, \cos^{2}\phi \, D_{T})}{\partial \phi}$ (9.183)

can be massaged into the form presented by Bryan (1969) and Wajsowicz (1993); that is the purpose of the remainder of this section.


next up previous contents
Next: 9.8.2 Zonal friction Up: 9.8 Old friction implementation Previous: 9.8 Old friction implementation
RC Pacanowski and SM Griffies, GFDL, Jan 2000