Group Abstract Group Abstract

Message Boards Message Boards

Solving equation on boundaries

Posted 1 year ago

Hello colleagues, I have a problem that is interesting.

I have the following equations:

1) diffusion equation

D[cb[t, x], {x, 2}] == D[cb[t, x], t]/d

d is the diffusion coefficient,

2) Adsorption on the boundary (x=0)

D[s[t], t] == k1*cb[t, 0]*s[t, x] -sat) -  k2*s[t]

The BC and IC:

D[s[t], t]==d*D[cb[t, x] at x=0

cb[t,a]== c0 (a and c0 constats)
cb[0,x] ==c0
s[0]==0

I found very akward to solve it. Any way to solve it? Or referentes about coupling ODE and PDE in Wolfram?

POSTED BY: Mnele Wolfram
6 Replies
POSTED BY: Mnele Wolfram
POSTED BY: Mariusz Iwaniuk

Apologize,

my bad.

D[cb[t, x], {x, 2}] == D[cb[t, x], t]]/d

D[s[t], t] == k1*cb[t, 0] * (s[t] -sat)  (* this is a BC*)

Double checking the equations in Wolfram now. No more mistakes.

POSTED BY: Mnele Wolfram

Thanks for the reply.

Sorry, I simplified the equations and some typos appeared;

D[cb[t, x], {x, 2}] == D[cb[t, x], t]/d

D[s[t], t] == k1*cb[t, 0] * (s[t] -sat)

s is only function of t.

POSTED BY: Mnele Wolfram

POSTED BY: Mariusz Iwaniuk

if x=0 why you have s[t, x] in the equation ?

What is : sat) ? and D[cb[t, x] ? you have a syntax errors.

POSTED BY: Mariusz Iwaniuk
Reply to this discussion
Community posts can be styled and formatted using the Markdown syntax.
Reply Preview
Attachments
Remove
or Discard