Solving U_x+U_y=1 with BC U(y,y/2)=y

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In summary, the conversation discusses solving a partial differential equation with a given boundary condition. The solution involves finding a homogeneous and non-homogeneous solution, and then adding them together. The final solution is checked to see if it satisfies the PDE and boundary condition. Ultimately, the solution is found to be U(x,y)=x.
  • #1
xdrgnh
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Homework Statement



U_x+U_y=1 with boundary condition U(y,y/2)=y

Homework Equations

The Attempt at a Solution



Well first I solved the homogeneous solution and got ax-ay where a is just a constant. Then for the non homogeneous solution I got ax+(1-a)y. After adding them both together and pluggin in the boundary condition I got U=x+(0)y? Is that right?
 
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  • #2
xdrgnh said:

Homework Statement



U_x+U_y=1 with boundary condition U(y,y/2)=y



Homework Equations




The Attempt at a Solution



Well first I solved the homogeneous solution and got ax-ay where a is just a constant. Then for the non homogeneous solution I got ax+(1-a)y. After adding them both together and pluggin in the boundary condition I got U=x+(0)y? Is that right?

It's easy enough to check it yourself. Does your solution ##U(x,y)=x## satisfy ##U_x+U_y = 1## and ##U(y,\frac y 2) = y##?
 
  • #3
It does. But I'm suspicious whenever a solution to a PDE comes out that nice.
 
  • #4
Hey, if you have the solution you have the solution. There's nothing left worry about. Good going.
 

FAQ: Solving U_x+U_y=1 with BC U(y,y/2)=y

1. What does the equation U_x+U_y=1 with BC U(y,y/2)=y represent?

The equation represents a partial differential equation with a boundary condition. This type of equation is often used to model physical systems in which the value of a function U depends on two variables, x and y, and the sum of the partial derivatives of U with respect to x and y is equal to a constant value of 1.

2. What is the significance of the boundary condition U(y,y/2)=y?

The boundary condition represents a specific value of the function U at a given point on the boundary of the system. In this case, the value of U is equal to the y-coordinate divided by 2 at the point (y,y/2). This boundary condition helps to further define the solution to the equation and make it more applicable to real-world scenarios.

3. How is this equation solved?

This equation can be solved using various mathematical techniques such as separation of variables, the method of characteristics, or by converting it into a standard form and using standard methods of solving partial differential equations. The specific method used may depend on the complexity of the equation and the desired level of accuracy in the solution.

4. What are some real-world applications of this equation?

This type of equation is commonly used in physics and engineering to model various systems such as heat flow, fluid dynamics, and electromagnetic fields. It can also be used in economics and finance to model the behavior of stock prices, interest rates, and other economic variables.

5. Are there any limitations to this equation?

Like any mathematical model, this equation is a simplification of a real-world system and may not accurately represent all aspects of the system. It also assumes certain assumptions and boundary conditions, which may not always hold true in reality. Therefore, it is important to carefully consider the limitations and assumptions of the equation when applying it to real-world problems.

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