Find the Equilibrium temperature distribution of a PDE

In summary: The standard way to solve such an equation is to first find the "characteristic polynomial" s^2- as+ k= 0 which has roots s= (a+/- \sqrt{a^2- 4k})/2. Depending on the values of a and k, there are three cases to consider- the roots are both real, one is real and one is a pair of complex conjugates, or both are complex conjugates.
  • #1
Engineer913
1
0

Homework Statement



1) What is the Equilibrium temperature distributions if α > 0?
2) Assume α > 0, k=1, and L=1, solve the PDE with initial condition u(x,0) = x(1-x)

Homework Equations



du/dt = k(d^2u/dx^2) - (α*u)

The Attempt at a Solution



I got u(x) = [(α*u*x)/2k]*[x-L] for Part#1 but this was told to be wrong

Part #2 I got α*u = -2, Also wrong.

Any insight how to correct this?
 
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  • #2
With the equilibrium condition you should just have a ODE.

[tex]\frac{d^2u}{dx^2}-\frac{a}{k}u=0[/tex]
 
  • #3
Engineer913 said:

Homework Statement



1) What is the Equilibrium temperature distributions if α > 0?
2) Assume α > 0, k=1, and L=1, solve the PDE with initial condition u(x,0) = x(1-x)

Homework Equations



du/dt = k(d^2u/dx^2) - (α*u)

The Attempt at a Solution



I got u(x) = [(α*u*x)/2k]*[x-L] for Part#1 but this was told to be wrong
Yes, it certainly is! How did you get that function?

Part #2 I got α*u = -2, Also wrong.

Any insight how to correct this?
An "equilibrium" solution is one that no longer changes: du/dt= 0 so the partial differential equation becomes k d^2u/dx^2- au= 0, a linear, homogeneous, second order, ordinary differential equations. If you are taking a course in "partial differential equations", you certainly should know how to solve such an equation.
 

1. What is a PDE and why is it important to find the equilibrium temperature distribution?

A PDE, or partial differential equation, is a type of mathematical equation that involves functions of multiple independent variables and their partial derivatives. It is important to find the equilibrium temperature distribution in order to understand how heat is distributed in a system and to predict how it will change over time.

2. How is the equilibrium temperature distribution of a PDE determined?

The equilibrium temperature distribution of a PDE is determined by solving the equation using mathematical techniques such as separation of variables or the method of characteristics. This results in a mathematical expression that describes the temperature distribution at any point in the system.

3. Can the equilibrium temperature distribution of a PDE change over time?

Yes, the equilibrium temperature distribution of a PDE can change over time if there are factors such as external heat sources or changes in the boundary conditions. In these cases, the PDE must be solved for each time step to determine the changing temperature distribution.

4. What are some real-world applications of finding the equilibrium temperature distribution of a PDE?

One common application is in studying heat transfer in materials and structures. For example, engineers may use PDEs to determine the temperature distribution in a building to optimize heating and cooling systems. PDEs are also used in modeling weather patterns and predicting climate change.

5. Are there any limitations to using PDEs to find the equilibrium temperature distribution?

While PDEs are a powerful tool for modeling temperature distributions, they do have some limitations. In complex systems, it may be difficult to accurately model all of the variables and boundary conditions. Additionally, the equations may become too complex to solve analytically, requiring the use of numerical methods which can introduce some error into the results.

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