Katie
Posts:
1
From:
Ottawa,Canada
Registered:
3/22/13


Overdetermined NDSolve
Posted:
Mar 22, 2013 4:17 AM


Hello,
I am trying to model an adsorption system which depends on length, radius and time (z,r,t). I am doing total of 5 equations (mass & energy) and I have 5 variables. However, mathematica tells that my system is overdetermined.
I hope you can help me finding where I am doing wrong.
I cut the NDSolve into two to make it easier to see.
Thank you so much.
NDSolve::overdet: There are fewer dependent variables, {cg[z,r,t],cp[z,r,t],q[z,r,t],Tg[z,r,t],Tw[z,r,t]}, than equations, so the system is overdetermined. >>
NumericalSolution=NDSolve[{(1ep)*rs*D[q[z,r,t],t]=ka*(3/rp)*(cp[z,r,t]cpe), ec*Dz*D[cg[z,r,t],{z,2}]vg*D[cg[z,r,t],z]=ec*D[cg[z,r,t],t]+ka*(3*(1ec)/rp)*(cg[z,r,t]cp[z,rp,t]), ep*D[cp[z,r,t],t]==ep*Deff*(2/r)*D[cp[z,r,t],{r,2}](1ep)*rs*D[q[z,r,t],t],k*D[Tg[z,r,t],{z,2}]ec*vg*rg*Cpg*D[Tg[z,r,t],z](2*hfd/rc)*(Tg[z,r,t]Tw[z,r,t])n*D[Tg[z,r,t],t]Hads*rp*D[q[z,r,t],t]=0, ((ro^2)(rc^2))*rw*Cpw*D[Tw[z,r,t],t]=2*rc*hfd*(Tg[z,r,t]Tw[z,r,t])2*ro*ho*(Tw[z,r,t]T0),
My boundary conditions: cg[z,r,0]=0, cg[0,r,t]=cginlet*(1Exp[(t/tao)]), Derivative[1,0,0][cg][h,r,t]=0, q[z,r,0]=0, cp[z,r,0]=0, Derivative[0,1,0][cp][z,0,t]=0,Deff*Derivative[0,1,0][cp][z,rp,t]=ka*(3/rp)*(cg[z,r,t]cp[z,rp,t]), Tg[z,r,0]=T0, Tg[0,r,t]=T0, Derivative[1,0,0][Tg][h,r,t]=0, Tw[z,r,0]=T0}, {cg,cp,q,Tg,Tw}, {z,0,h}, {r,0,rp}, {t,0,8000}, Method=EF=82=AE{"MethodOfLines", "SpatialDiscretization"=EF=82=AE{"TensorProductGrid", "MinPoints"=EF=82=AE150,PrecisionGoal=EF=82=AE3}}]

