trouble with NDSolve
- To: mathgroup at smc.vnet.net
- Subject: [mg63590] trouble with NDSolve
- From: lahm <mifdavid at yahoo.com>
- Date: Fri, 6 Jan 2006 05:24:34 -0500 (EST)
- Sender: owner-wri-mathgroup at wolfram.com
i have trouble with solving a diffusion problem with NDSolve. I would like to get a 2D concentration profile using second Fick's law dc/dt=d2c/dx2 + d2c/dy2. c is concentration and is function of t,x and y. The initial condition is concentration=1 everywhere. The boundary conditions are c=1 for x=1, y=1 and y=-1. On x=0, however, the concentration is 0, but only for -0.01<y<0.01, the other part of x=0 acts neutral, is neither a sink nor an inlet, concentration therefore is determined by the sink and the boundaries. Now when I try to imput that c=0 only at a part of x=0, I get the message that boundary condition is not specified on a single edge of the boundary of the computational domain. NDSolve::bcedge: I tried several different approaches, but all of them have failed. There's always something wrong so mathematica always encounters some problem. I can't make only one part of the boundary work as a sink an the other to be neutral. Please help!
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