Re: Convective diffusion equation in 2D
- To: mathgroup at smc.vnet.net
- Subject: [mg79817] Re: Convective diffusion equation in 2D
- From: dantimatter <dantimatter at gmail.com>
- Date: Sun, 5 Aug 2007 04:56:54 -0400 (EDT)
- References: <f8v09f$cbk$1@smc.vnet.net><f91i6t$5hi$1@smc.vnet.net>
> With[{\[ScriptCapitalD] = 1/8, v = 1/4},
> sol = NDSolve[{
> D[u[x, y, t],
> t] == \[ScriptCapitalD] (D[u[x, y, t], {x, 2}] +
> D[u[x, y, t], {y, 2}]) - v*D[u[x, y, t], x],
> u[-1, y, t] == 0, u[1, y, t] == 0,
> u[x, -1, t] == 0, u[x, 1, t] == 0,
> u[x, y, 0] == Piecewise[{{1, Sqrt[x^2 + y^2] <= 0.5}}, 0]},
> u[x, y, t], {x, -1, 1}, {y, -1, 1}, {t, 0, 2}
> ]
> ]
ok, so i got the above to work when i ran it on a more powerful
machine. thanks for the advice. the problem i'm having now is in
defining the boundary conditions. what i'd like is to have a circular
'source' at which the concentration is always constant, but i don't
know about any of the other boundaries. i guess i could say that the
concentration is zero at infinity. any advice on how to implement
these boundary conditions??
many thanks,
dan