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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 Havzalı 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

> 

> 




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