On Jan 13, 2013, at 12:30 PM, John Assael wrote:
> I know
> - properties dw,cpw,kw,d,cp,k and I know Q.
> I want to calculate the temperature rise as a function of time
> ----
> So I create a mesh and set the CellVariable
> dT = CellVariable(name = r'$\Delta T$',
> mesh = mesh, value=0.)
>
> Q is the amount of energy supplied (usually something like 1.5*10^9)
>
> then my first equation becomes:
> eq1 = (TransientTerm() == DiffusionTerm(coeff=(tcw/(denw*cpw))) +
> (1/(denw*cpw))*(Qw))
>
> and the second:
> eq2 = (TransientTerm() == DiffusionTerm(coeff=(tc/(den*cp))))
>
> Then I am setting the constrain of X**2 + Y**2 <= a**2 to be 1 as it is the
> wire that is being heated by Q energy
>
> However I get no results. Are the constrain and the equations right?
It looks like you're trying to solve two different equations in two different
regions with a matched internal boundary condition at r = a, correct?
FiPy is not designed to work that way. FiPy expects its governing equations to
be valid everywhere with boundary conditions (constraints) applied only on the
exterior of the domain.
The way to approach this for your problem is to solve
d cp dT/dt - k \DeltaT = Q
everywhere and to have different values for {d, cp, k, Q} inside the wire and
inside the fluid. The internal boundary condition will take care of itself.
Several examples, starting with examples.diffusion.mesh1D show how to set up
spatially varying coefficients.
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