Re: NDSolve initial value problem

*To*: mathgroup at smc.vnet.net*Subject*: [mg99239] Re: NDSolve initial value problem*From*: dh <dh at metrohm.com>*Date*: Thu, 30 Apr 2009 06:25:45 -0400 (EDT)*References*: <gt90l4$l1t$1@smc.vnet.net>

Hi Murat, the solution to your DEQ must be continuous. Therefore, T[0,y]==Piecewise[{0,-1< y<1}]==0 (where I delete the superfluous part) and: T[x, 1] == 1 for x==0 are inconsistent. Daniel Murat HavzalÄ± wrote: > Dear Mathematica users; > > > > I am trying to solve liquid heat/mass transfer equation with mixed boundary > conditions. > > My code looks like this: > > > > pe=0.5; > > u[y]=1-y^2; > > > > sol=NDSolve[ > > { > > pe*u[y]*D[T[x,y],x]==D[T[x,y],y,y], > > > > T[0,y]==Piecewise[{{-y,y<=-1},{0,-1< y<1},{1,1<=y}}], > > > > T[x,1]==1, > > (D[T[x,y],y]/.y->-1)==-1 > > > > }, > > T,{x,0,1},{y,-1,1},SolveDelayed->True]; > > > > This returns inconsistent initial boundary conditions error. > > I also tried to make the piecewise initial condition, a numerical function > namely: > > > > initial[y_?NumericQ]:=Piecewise[{{-y,y<=-1},{0,-1< y<1},{1,1<=y}}] > > > > > > However this did not work, too. I understand that there is a similar > question already asked about this subject, > > and I tried my best to convert it to my problem but couldn't. I couldn't > find the code but I also tried to give the > > initial piecewise function as a interpolating function, it returned the same > response. > > Any help would be appreciated. > > > > Thanks. > > > > Murat Havzal > >