Exploring the Shape of Characteristic Curves for a PDE

In summary, the characteristic curves for the given partial differential equation form a quadratic shape.
  • #1
jimmycricket
116
2

Homework Statement


suppose [tex]u(x,y)[/tex] satisfies the partial differential equation:
[tex]-4y\frac{\partial u}{\partial x}+\frac{\partial u}{\partial y}=0[/tex]
Find the characteristic curves for this equation and name the shape they form

The Attempt at a Solution


[tex]\frac{dy}{dt}=1 \Longrightarrow y=t+y_0[/tex]
[tex]\frac{dx}{dt}=-4y=-4(t+y_0) \Longrightarrow x=-2t^2-4y_0t+x_0[/tex]

What can I say about the shape these curves form?
 
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  • #2
jimmycricket said:

Homework Statement


suppose [tex]u(x,y)[/tex] satisfies the partial differential equation:
[tex]-4y\frac{\partial u}{\partial x}+\frac{\partial u}{\partial y}=0[/tex]
Find the characteristic curves for this equation and name the shape they form



The Attempt at a Solution


[tex]\frac{dy}{dt}=1 \Longrightarrow y=t+y_0[/tex]
[tex]\frac{dx}{dt}=-4y=-4(t+y_0) \Longrightarrow x=-2t^2-4y_0t+x_0[/tex]

What can I say about the shape these curves form?

[itex]y[/itex] is a first-order polynomial in [itex]t[/itex]. [itex]x[/itex] is a quadratic in [itex]t[/itex]. Therefore [itex]x[/itex] is a quadratic in [itex]y[/itex]. What shape does the graph of a quadratic function have?
 

Related to Exploring the Shape of Characteristic Curves for a PDE

1. What is a PDE and why is it important in scientific research?

A PDE, or partial differential equation, is a type of mathematical equation that involves multiple variables and their partial derivatives. It is important in scientific research because it is used to model various physical phenomena, such as heat transfer, fluid dynamics, and quantum mechanics.

2. How does one explore the shape of characteristic curves for a PDE?

To explore the shape of characteristic curves for a PDE, one must first solve the PDE using appropriate methods, such as separation of variables or numerical techniques. Then, the characteristic curves can be traced by plotting the solution in the space of independent variables.

3. What information can be gained by exploring the shape of characteristic curves for a PDE?

By exploring the shape of characteristic curves for a PDE, one can gain insights into the behavior of the solution and how it changes with respect to the independent variables. This information can be used to analyze the stability, convergence, and accuracy of the solution.

4. Are there any limitations to exploring the shape of characteristic curves for a PDE?

Yes, there are limitations to exploring the shape of characteristic curves for a PDE. This method may not be applicable to all types of PDEs, such as nonlinear or nonhomogeneous equations. Additionally, the accuracy of the results may be affected by the chosen discretization method and the grid resolution.

5. How can the results from exploring the shape of characteristic curves for a PDE be validated?

The results from exploring the shape of characteristic curves for a PDE can be validated by comparing them with analytical solutions, if available, or by conducting convergence studies with decreasing grid resolutions. Additionally, the results can be verified by using different numerical methods to solve the PDE and comparing the solutions.

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