# Homework Help: Boundary Condition

1. Nov 1, 2009

### mhmonon

Hi all,
I am facing difficulties about boundary condition in Hollow Cylinder. its like wave diffusion equation in hollow cylinder. can anyone help me out to solve this problem. I need some good reverences.
Thank you

2. Nov 1, 2009

### tiny-tim

Welcome to PF!

Hi mhmonon! Welcome to PF!
We're all very reverend here.

Show us how far you got, and where you're stuck, and then we'll know how to help!

3. Nov 1, 2009

### FredGarvin

You need to be more precise with what you are doing. That will directly influence what the BCs are.

4. Nov 1, 2009

### mhmonon

here I attached the equation with the boundary value.

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5. Nov 1, 2009

### FredGarvin

I think your nomenclature is a bit different than what I am used to seeing. You are solving a PDE for the velocity potential, correct? Your boundary conditions are on omega which is usually circular frequency. Is that correct?

6. Nov 1, 2009

### mhmonon

actually it is a wave diffusion equation in hollow cylindrical problem.. I think I can solve this problem.

7. Nov 2, 2009

### HallsofIvy

that is the equation for r, after you have separted variables r and $\theta$. One "unstated" boundary condition is that the function must be finite at r= 0. That gives you one of your constants immediately.

8. Nov 2, 2009

### mhmonon

hi HallsofIvy,
Thanks for your reply. Yep you are right. But I am facing here another problem. The problem is that I have no condition at r=0; Instead of r=0 I have another condition that is ri(internal radius)=0. So I can not eliminate one. Bye