What are the Boundary Conditions for Solving Poisson's Equation?

In summary, the purpose of Laplace's/Poisson's equation is to convert a geometrical problem into a differential equation. The appropriate boundary conditions for Poisson's equation can be determined by considering the potential and local charge density. It is a linear equation as the potential does not appear and the charge density is a function of x,y,z. The method to solve this equation will depend on the exact form of the charge density and the best boundary conditions will also vary. Knowing the potential at all points along a closed surface allows for the definition of the potential everywhere inside.
  • #1
DivergentSpectrum
149
15
As i understand, the purpose of laplaces/poissons equation is to recast the question from a geometrical one to a differential equation.
im trying to figure out what are the appropriate boundary conditions for poissons equation:

http://www.sciweavers.org/upload/Tex2Img_1418842096/render.png
where v is potential and p is the local charge density

Also, what method do i use to solve this equation? I can't remember a thing about pde's but i have some knowledge of ODE's. It appears linear Because V doesn't show up anywhere, and P is a function of x,y,z but I don't really know where to begin with this though.
 
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  • #2
The boundary conditions will be v(x,y,z) and it's partials for some specific points.
The exact method to solve, and the best boundary conditions for that matter, will depend on the exact form of p(x,y,z).

Note: we'd normally write: $$\nabla^2\phi = \frac{\rho_{free}}{\epsilon_0}$$ ... since this does not assume a specific coordinate system.
 
  • #3
So if i know V at all values along some closed surface then V is defined everywhere inside right?
 

FAQ: What are the Boundary Conditions for Solving Poisson's Equation?

1. What are boundary conditions for PDE?

Boundary conditions for PDE (Partial Differential Equations) are a set of conditions that must be specified at the boundaries of a domain in order to uniquely determine a solution. These conditions can be either Dirichlet, Neumann, or Robin boundary conditions.

2. What is the purpose of boundary conditions in PDEs?

The purpose of boundary conditions in PDEs is to specify the behavior of the solution at the boundaries of the domain. This helps in determining a unique solution for the PDE and also reflects physical constraints of the problem being studied.

3. How are boundary conditions different from initial conditions in PDEs?

Boundary conditions are specified at the boundaries of the domain, while initial conditions are specified at a single time or spatial point. Boundary conditions are used to determine a unique solution, while initial conditions are used to specify the behavior of the solution at the beginning of the problem.

4. What are the three types of boundary conditions in PDEs?

The three types of boundary conditions in PDEs are Dirichlet boundary conditions, Neumann boundary conditions, and Robin boundary conditions. Dirichlet boundary conditions specify the value of the solution at the boundary, Neumann boundary conditions specify the derivative of the solution at the boundary, and Robin boundary conditions are a combination of both.

5. How do boundary conditions affect the solution of a PDE?

Boundary conditions play a crucial role in determining the behavior of the solution to a PDE. They can affect the uniqueness of the solution, convergence of numerical methods, and the physical interpretation of the solution. Improperly specified boundary conditions can lead to incorrect solutions or even non-existence of solutions.

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