Date: Mar 22, 2013 4:17 AM
Author: Katie
Subject: Overdetermined NDSolve

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[{(1-ep)*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*(1-ec)/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}]-(1-ep)*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*(1-Exp[-(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}}]