- #1
tomwilliam
- 144
- 2
EDIT: The subscripts in this question should all be superscripts!
I'm trying to solve a temperature problem involving the diffusion equation, which has led me to the expression:
X(x) = Cekx+De-kx
Where U(x,y) = X(x)Y(y)
and I am ignoring any expressions where Y(y)=0 or X(x)=0 for all values of their variables as these are trivial solutions.
I'm told I can simplify things by applying one of the boundary conditions:
As x tends towards infinity, U(x,y) tends towards 0.
So my question is, how do I apply this to the general solution I've found for X(x)?
I know that Y(y) is not zero, so I effectively have X(x) going to zero as x tends towards infinity. So I need to work out what happens to Cekx + De-kx. As 1/x tends to 0 as x tends to infinity, can I assume that D/ekx also tends towards 0? Or does it tend to D? And what about C?
Thank in advance for any help
Homework Statement
I'm trying to solve a temperature problem involving the diffusion equation, which has led me to the expression:
X(x) = Cekx+De-kx
Where U(x,y) = X(x)Y(y)
and I am ignoring any expressions where Y(y)=0 or X(x)=0 for all values of their variables as these are trivial solutions.
I'm told I can simplify things by applying one of the boundary conditions:
As x tends towards infinity, U(x,y) tends towards 0.
Homework Equations
The Attempt at a Solution
So my question is, how do I apply this to the general solution I've found for X(x)?
I know that Y(y) is not zero, so I effectively have X(x) going to zero as x tends towards infinity. So I need to work out what happens to Cekx + De-kx. As 1/x tends to 0 as x tends to infinity, can I assume that D/ekx also tends towards 0? Or does it tend to D? And what about C?
Thank in advance for any help
Last edited: