# Diff of /trunk/doc/user/Models.tex

revision 2104 by jfenwick, Thu Nov 27 05:36:47 2008 UTC revision 2108 by gross, Fri Nov 28 05:09:23 2008 UTC
# Line 211  saveVTK("u.xml",velocity=v,pressure=p) Line 211  saveVTK("u.xml",velocity=v,pressure=p)
211  \end{python}  \end{python}
212
213  \section{Darcy Flux}  \section{Darcy Flux}
214  We want to calculate the velocity $u$ and pressure $p$ on a domain $\Omega$ such that  We want to calculate the velocity $u$ and pressure $p$ on a domain $\Omega$ solving
215    the Darcy flux problem \index{Darcy flux}\index{Darcy flow}
216  \label{DARCY PROBLEM}  \label{DARCY PROBLEM}
217  \begin{array}{rcl}  \begin{array}{rcl}
218  u\hackscore{i} + \kappa\hackscore{ij} p\hackscore{,j} & = & g\hackscore{i} \\  u\hackscore{i} + \kappa\hackscore{ij} p\hackscore{,j} & = & g\hackscore{i} \\
# Line 314  returning $(Qp,w)$ where $w$ is the solu Line 315  returning $(Qp,w)$ where $w$ is the solu
315  We use $Q^*Q$ as a a preconditioner for the iteration operator $Q^* ( I - (I+D^*D)^{-1} ) Q$.  We use $Q^*Q$ as a a preconditioner for the iteration operator $Q^* ( I - (I+D^*D)^{-1} ) Q$.
316
317  \subsection{Functions}  \subsection{Functions}
318    \begin{classdesc}{DarcyFlow}{domain}
319    opens the Darcy flux problem\index{Darcy flux} on the \Domain domain.
320    \end{classdesc}
321
322    \begin{methoddesc}[DarcyFlow]{initialize}{\optional{f=Data(), \optional{fixed_u_mask=Data(), \optional{eta=1, \optional{surface_stress=Data(), \optional{stress=Data()}}}}}}
323    assigns values to the model parameters. In any call all values must be set.
324    \var{f} defines the external force $f$, \var{eta} the viscosity $\eta$,
325    \var{surface_stress} the surface stress $s$ and \var{stress} the initial stress $\sigma$.
326    The locations and compontents where the velocity is fixed are set by
327    the values of \var{fixed_u_mask}. The method will try to cast the given values to appropriate
328    \Data class objects.
329    \end{methoddesc}
330
331
332  \subsection{Example: Gravity Flow}  \subsection{Example: Gravity Flow}
333

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