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Standard PDE: solution wanted.

  • To: mathgroup at smc.vnet.net
  • Subject: [mg42464] Standard PDE: solution wanted.
  • From: "kl" <klimm1290 at yahoo.com>
  • Date: Thu, 10 Jul 2003 03:36:49 -0400 (EDT)
  • Organization: Purdue University
  • Sender: owner-wri-mathgroup at wolfram.com

I am trying to solve the following PDE which is a form of diffusion
equation.

d/dt(rho) = div [D*grad(rho)] + r

Assume D to be constant
r is constant
rho is the only dependent variable and depends on space coordinates and
time.

As it can be seen, it is a very common equation and similar equation with
appropriate change in parameters can be found in heat conduction problems in
solids.

I am trying to solve this equation in 2D Cartesian coordinate system. My
domain is a rectangle of length L and height H.
Hence my equation becomes -

d/dt(rho) = D*d2/dx2(rho) + D*d2/dy2(rho) + r

Initial condition for this problem is -
All over the domain, rho is known and constant at time t = 0 (you can call
it rho_init)

Boundary conditions for this problem are -
Top surface is open and hence rho = rho_init at that surface for all times t
Other three surfaces are impermeable and hence grad(rho) = d/dx(rho) +
d/dy(rho) = 0

Can anyone tell me how to find this solution of the problem using
mathematica?
Do anyone know of an analytical solution to this problem? - If so please
direct me to the book where I can find that solution.  (I am pretty sure
that analytical solution exists, I am just not being able to find it)



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