| Author |
Comment/Response |
Guillaume
|
 01/24/06 07:32am
ok I have a lil problem here,
I'd like to Plot d(t)=a*Integrate[dT(0,x)/dx -dT(L,x)/dx]
T is only numerically known from the heat equation with special boundary conditions : dT/dt = d2T/dx2 .
here is my prog :
cl0 = {y[0, t]==Tair, Derivative[1, 0][y][10, t] == 0}
cl = {Derivative[1,0][y][0,t]==(-1/k)*(h*(y[0, t] - Tair) - (1 - Albedo)Qsol),Derivative[1, 0][y][10, t] == 0};
eq = Derivative[0, 1][y][x, t] == dif*Derivative[2, 0][y][x, t];
ci = y[x, 0]==T0;
solution = NDSolve[{eq , cl , ci }, y, {x, 0, 10}, {t, 0, 259200}]
diflux = Derivative[1, 0][y][0, t] - Derivative[1, 0][y][10, t]
d=a*Integrate[dT(0,x)/dx -dT(L,x)/dx]
Plot[Evaluate[d[t] /. solold], {t, 0, 259200},
PlotStyle -> {{RGBColor[0, 0, 0]}}]
the problem is that Mathematica can't integrate the numerical value from the NDsolve.
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