| Author | Message | ||
     Alex Skordos (aas) New member Username: aas Post Number: 1 Registered: 03-2009 |
can I use flexpde to solve a free boundary problem? The specific problem of interest is flow through porous media: div(k grad(p)=0 and the free boundary Gamma can be defined as n dGamma/dt=-n k grad(p) with appropriate initial and boundary conditions. | ||
| Robert G. Nelson (rgnelson) Moderator Username: rgnelson Post Number: 1220 Registered: 06-2003 |
In your problem, the NATURAL Boundary Condition specifies the outward normal component of k*grad(p). You have not defined gamma, so I don't know if there are difficulties lurking there, but in principle the specification NATURAL(p) = -dt(gamma) will impose the desired boundary condition. See "Natural Boundary Condition" in the Help Index. Many of our sample problems use boundary conditions of this type. "Samples | Applications | heatflow | radiative_boundary.pde" shows a radiative loss at the boundary. "Samples | Usage | eigenvalues | 3D_plate.pde" shows a vibration problem with free boundaries. | ||
| Alex Skordos (aas) New member Username: aas Post Number: 2 Registered: 03-2009 |
many thanks - Gamma is the position of one boundary at which pressure is prescribed p(Gamma,t)=po would this specification be possible in conjuciton with the natural boundary condition? |