No error message?
- To: mathgroup at smc.vnet.net
- Subject: [mg79451] No error message?
- From: meaton01 <mike.eaton at gmail.com>
- Date: Fri, 27 Jul 2007 05:47:36 -0400 (EDT)
OK, this is for the geniuses who pushed me in the right direction on the 2D heat equation:
D[u[x, y, t], t]*densitymix*cpmix == Gen[t] + conductivitymix*D[u[x, y, t], {x, 2}] + conductivitymix*D[u[x, y, t], {y, 2}]
This works brilliantly, and I can solve this for a Gen[t] term which is merely time dependent (in any degree of complexity). However, I'd like Gen[t] to be a function of u[0,0,t] (the centerline temperature at a given time). For instance
Gen[t_]:= Cons*Exp[-Ea/(R*u[0,0,t])]
While this is not exactly the form (it's much longer and hideous), it's the general idea. Of course, I correctly define Cons, Ea, and R prior to evaluation, I define my Gen[t_] the normal way, and when I run NDSolve on the following:
sol = NDSolve[{D[u[x, y, t], t]*densitymix*cpmix == Re[Gen[t]] + conductivitymix*D[u[x, y, t], {x, 2}] + conductivitymix*D[u[x, y, t], {y, 2}], u[x, y, 0] == 278.15,u[-1, y, t] == 278.15, u[1, y, t] == 278.15, u[x, -1, t] == 278.15,u[x, 1, t] == 278.15}, {u[x, y, t]}, {t, 0, 10}, {x, -1,1}, {y, -1, 1}, PrecisionGoal -> 4,AccuracyGoal -> 4]
I get two errors:
NDSolve::rdelay: -- Message text not found -- (t) >>
NDSolve::rdelay: -- Message text not found -- (t) >>
Just FYI: My generation term gives complex parts (although they are effectively zero), which is why I'm extracting the reals.
I've googled this error, and I understand it's something wrong with my input, but I don't know how to tell mathematica that I want the generation term (which is really only a function of time, although it depends on u[x,y,t]).
Your help is much appreciated. I'm happy to post the whole worksheet if necessary.
Thanks so much,
Mike Eaton