Seperation of variables in the 2 dimensional wave equation

In summary, the problem at hand is to solve the 2-dimensional wave equation using separation of variables. The wave equation is given as (\delta^{2}u)/(\deltat^{2})=4((\delta^{2}u)/(\deltax^{2})+(\delta^{2}u)/(\deltay^{2})), with boundary conditions V(0,y,t)=V(a,y,t)=0, V(x,0,t)=V(x,b,t)=0, and initial conditions V(x,y,0)=0 and (\deltaV)/(\deltat)(x,y,0)=g(x,y)=(\pi/2-x)(\pi-y). The solution is shown to be V(x
  • #1
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[SOLVED] Seperation of variables in the 2 dimensional wave equation

I'd like to apologize right away for the terrible formatting. I was trying to make it pretty and easy to read but I guess I'm just not used the system yet and I had one problem after another. As you'll see at one point the formatting pretty much went out the window. I hope you can still figure out what I'm trying to say. Sorry!

Homework Statement


Solve the wave equation in 2 dimensions by separation of variables.
([tex]\delta[/tex][tex]^{2}[/tex]u)/([tex]\delta[/tex]t[tex]^{2}[/tex])=4(([tex]\delta[/tex][tex]^{2}[/tex]u)/([tex]\delta[/tex]x[tex]^{2}[/tex])+([tex]\delta[/tex][tex]^{2}[/tex]u)/([tex]\delta[/tex]y[tex]^{2}[/tex]))
a=[tex]\pi[/tex]/2 , b=[tex]\pi[/tex]
V(0,y,t)=V(a,y,t)=0
V(x,0,t)=V(x,b,t)=0
V(x,y,0)=0
([tex]\delta[/tex]V)/([tex]\delta[/tex]t)(x,y,0)=g(x,y)=([tex]\pi[/tex]/2-x)([tex]\pi[/tex]-y)
Show that
V(x,y,t)=Sigma(n=1,[tex]\infty[/tex])Sigma(m=1,[tex]\infty[/tex])(((sin(2sqrt(lambda sub(nm))t))/(nm*sqrt(lambda sub(nm)))*sin(2nx)sin(m)y)
where
lambda sub(nm)=4n^2+m^2

Homework Equations


All I know is it's going to be semi-related to the general solution of the wave equation:
([tex]\delta[/tex][tex]^{2}[/tex]u)/([tex]\delta[/tex]t[tex]^{2}[/tex])=(k^2)*([tex]\delta[/tex][tex]^{2}[/tex]u)/([tex]\delta[/tex]x[tex]^{2}[/tex])

The Attempt at a Solution


I know that k^2 is going to be equal to the 4. Other then that I'm lost. If possible, well explained steps would be best so I can figure out what I'm doing.

Thanks for your help!
 
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  • #2
[SOLVED] Seperation of variables in the 2 dimensional wave equation

I'd like to apologize right away for the terrible formatting. I was trying to make it pretty and easy to read but I guess I'm just not used the system yet and I had one problem after another. As you'll see at one point the formatting pretty much went out the window. I hope you can still figure out what I'm trying to say. Sorry!

Homework Statement


Solve the wave equation in 2 dimensions by separation of variables.
([tex]\delta[/tex][tex]^{2}[/tex]u)/([tex]\delta[/tex]t[tex]^{2}[/tex])=4(([tex]\delta[/tex][tex]^{2}[/tex]u)/([tex]\delta[/tex]x[tex]^{2}[/tex])+([tex]\delta[/tex][tex]^{2}[/tex]u)/([tex]\delta[/tex]y[tex]^{2}[/tex]))
a=[tex]\pi[/tex]/2 , b=[tex]\pi[/tex]
V(0,y,t)=V(a,y,t)=0
V(x,0,t)=V(x,b,t)=0
V(x,y,0)=0
([tex]\delta[/tex]V)/([tex]\delta[/tex]t)(x,y,0)=g(x,y)=([tex]\pi[/tex]/2-x)([tex]\pi[/tex]-y)
Show that
V(x,y,t)=Sigma(n=1,[tex]\infty[/tex])Sigma(m=1,[tex]\infty[/tex])(((sin(2sqrt(lambda sub(nm))t))/(nm*sqrt(lambda sub(nm)))*sin(2nx)sin(m)y)
where
lambda sub(nm)=4n^2+m^2

I would have left the relevant equations and attempted solutions parts, but for some reason I can't get it to post with that and I didn't have very much to say in those anyway. If possible, well explained steps would be best because I'm kind of lost, and then I can figure out what I'm doing.

Thanks for your help!
 
  • #3
Dang it, it was posting but it came up with an error. Um... I don't know how to delete this right off hand, but give me a minute I'll see if I can figure it out.
 
  • #4
It doesn't seem I can delete. If an admin reads this please delete this and one of the other copies.
 
  • #5
I'll set this one and one other to solved to try to remove the amount of people opening it.
 
  • #6
Sorry for the copies.
 
  • #7
Please delete this one, setting it to solved to try to help remove additional readers of the copy.
 

1. What is the 2-dimensional wave equation?

The 2-dimensional wave equation is a partial differential equation that describes the propagation of waves in two dimensions. It is commonly used in physics and engineering to model various physical phenomena, such as sound and electromagnetic waves.

2. What does "separation of variables" mean in the context of the 2-dimensional wave equation?

Separation of variables is a mathematical technique used to solve partial differential equations, such as the 2-dimensional wave equation. It involves breaking down the equation into simpler equations by assuming that the solution can be expressed as a product of functions of individual variables.

3. Why is separation of variables important in solving the 2-dimensional wave equation?

The 2-dimensional wave equation is a complex equation that is difficult to solve directly. Separation of variables simplifies the equation and allows for a step-by-step solution, making it easier for scientists and engineers to analyze and understand the behavior of waves in two dimensions.

4. What are the steps for solving the 2-dimensional wave equation using separation of variables?

The steps for solving the 2-dimensional wave equation using separation of variables are as follows:
1. Substitute the assumed solution into the equation.
2. Separate the variables into separate equations.
3. Solve each equation separately.
4. Combine the solutions to get the final solution.
5. Apply any necessary boundary conditions.

5. What are some real-world applications of the 2-dimensional wave equation and the technique of separation of variables?

The 2-dimensional wave equation and separation of variables are used in a variety of fields, including acoustics, electromagnetics, and fluid dynamics. Some specific applications include modeling sound waves in musical instruments, predicting the behavior of electromagnetic waves in antennas, and studying the motion of water waves in oceans and lakes.

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