       using interpolating function as initial condition to Ndsolve

• To: mathgroup at smc.vnet.net
• Subject: [mg102766] using interpolating function as initial condition to Ndsolve
• From: Santhosh <santhosh833 at gmail.com>
• Date: Wed, 26 Aug 2009 07:45:23 -0400 (EDT)

```hi all,

I am solving a set of four pdes (first order in time and second order
in space) using NDsolve. I am able to solve for arbitrary initial
conditions. What I am interested is fist solve with some random
initial conditions and get the steady state solution. I want to use
this solution as initial condition(e.g cf[0,z]=f(z)....) for the next
computations. I could not figure out how to use interpolating function
as initial condition.
can anybody have any idea?

Thank you.

here is my code
sol = NDSolve[
{
D[cf[t, z], t] + v D[cf[t, z], z] - a1 (cc[t, z] - cf[t, z]) ==
0,
D[tf[t, z], t] + v D[tf[t, z], z] - a2 (tc[t, z] - tf[t, z]) -
a3 (tw - tf[t, z]) == 0,
D[cc[t, z], t] - a4 (cf[t, z] - cc[t, z]) -
a5 r[cc[t, z], tc[t, z]] == 0,
D[tc[t, z], t] - a6 (tf[t, z] - tc[t, z]) -
a7 r[cc[t, z], tc[t, z]] - a8 D[tc[t, z], z, z] == 0,
cf[t, 0] == c0,
tf[t, 0] == t0, (D[tc[t, z], z] /. z -> 0) ==
0, (D[tc[t, z], z] /. z -> length) == 0,
cf[0, z] == c0, tf[0, z] == t0, cc[0, z] == c0, tc[0, z] == t0
},
{cf, tf, cc, tc}, {t, 0, tfinal}, {z, 0, length}
]

```

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