Separation of variables, laplace equation

In summary, the conversation discusses solving for the potential within a pipe with a small gap between two coaxial pipes maintained at a potential difference V. The Laplace equation and boundary conditions are used to determine the potential at different points within the pipe. Separation of variables and fitting coefficients can be used to solve for the potential near the gap.
  • #1
merrypark3
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Homework Statement


Two coaxial pipes(radius a) of the same diameter with a small gap between them are maintained at a potential difference V.

By separation of variables and fitting coefficient, guess the potential within the pipe, near the gap.



Homework Equations





The Attempt at a Solution



Cylindrical laplace equation.
[itex] \frac{d^2 R}{dr ^2} + \frac{1}{r} \frac{dR}{dr} =0[/itex]

Wow can I handle the boundary condition at r=a? R=V/2 or R=-V/2 or R=0?

 
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  • #2


Hello there,

Thank you for your post. It seems like you are trying to solve for the potential within the pipe near the gap using the Laplace equation. In order to handle the boundary condition at r=a, you can use the fact that the potential at the surface of a conductor is constant. Therefore, at r=a, the potential must be equal to V/2. Using this information, you can solve for the potential at different points within the pipe and near the gap. I suggest trying to solve for the potential using separation of variables and fitting coefficients, as mentioned in the homework statement. Let me know if you have any further questions. Good luck with your research!
 

FAQ: Separation of variables, laplace equation

What is separation of variables?

Separation of variables is a method used in solving partial differential equations, specifically the Laplace equation. It involves separating a multi-variable equation into several single-variable equations, which can then be solved independently.

Why is separation of variables useful?

Separation of variables is useful because it allows us to solve complex differential equations by breaking them down into simpler, single-variable equations. This makes the problem more manageable and easier to solve.

What is the Laplace equation?

The Laplace equation is a second-order partial differential equation that describes the behavior of a scalar field in space. It is commonly used in physics and engineering to model various physical phenomena, such as heat transfer, electrostatics, and fluid flow.

How is separation of variables applied to the Laplace equation?

To apply separation of variables to the Laplace equation, we first assume that the solution can be expressed as a product of two functions, one of which is a function of only one variable and the other is a function of the remaining variables. We then substitute this into the Laplace equation and use algebraic manipulation to separate the variables and solve for each individual function.

What are the limitations of separation of variables?

Separation of variables is not applicable to all types of partial differential equations. It is only effective for linear, homogeneous equations with certain boundary conditions. Additionally, the method may not always yield a solution, and even when it does, the resulting solution may not be unique.

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