Run Time Change of Boundary Conditions
 

Hi,
I am trying to implement a differential LES filter.
So I created a LESfilter class which should solve an elliptic equation for the un-filtered field to obtain the filtered one.
The problem is that I often have to filter fields calculated from other fields, and on solid walls they have "calculated" boundary conditions.
To solve the elliptic equation I should turn every "calculated" condition into a "fixed value" Dirichlet one, with the same value.
And this should be done inside the operator() function of the filter class.
Is it possible? How can I do it?

Also I am not really familiar on how openFoam requests the specification of the linear solver used to solve the PDEs, since it appears bounded to the solved variable, and not to the equation. Is it possible to specify a default solver? Is it possible to specify more than a solver for a single variable? Because, for example, I have to solve the PISO momentum equation for U, with a non-symmetric solver, and than filter U, with a symmetric solver.

Thanks,
Matteo