Boundary Conditions for an infinite rectangular pipe

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Homework Help Overview

The discussion revolves around setting up boundary conditions for a potential problem in an infinite rectangular pipe, specifically considering the implications of the pipe's infinite length on the dimensional analysis and boundary conditions applied.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants are exploring the assignment of axes and the implications of the pipe being infinite in one direction. There is discussion about whether the problem should be treated as a 2-D Laplace equation due to the infinite length along the z-axis.

Discussion Status

Participants are actively questioning the setup of the axes and the corresponding boundary conditions. Some have provided clarifications on their interpretations of the axes, while others are considering the independence of the potential from the z-axis due to the pipe's infinite nature. No consensus has been reached yet, but there is a productive exploration of the problem's setup.

Contextual Notes

There are indications of confusion regarding the assignment of axes and the definition of boundary conditions, which may affect the overall understanding of the problem. Participants are referencing a diagram and textbook examples to guide their reasoning.

guyvsdcsniper
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Homework Statement
An infinite rectangular pipe with sides a, has two opposite sides at voltage V
(front and back) and at voltage V=0 (top and bottom).

Find the potential inside the pipe.
Relevant Equations
Fourier Sine Trick
Does setting up the problem symmetrically on this axis and the boundary conditions applied make sense? I don't believe I will have a problem solving for the potential inside, but i just want to make sure I have my B.C and axis correct before proceeding.

IMG_0381.jpg


EDIT:

Or should this be a 2-D lapace equation since the pipe is infinitely long, making this independent of the z axis?
 
Last edited:
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I'm a bit confused about how you are assigning the axes.
I'll call the left right axis X, the vertical axis Z and the lower left/ upper right axis in the picture Y. From that and the text description, I would say the pipe is infinite in the X axis and width a in the other two. The voltage is V on the faces normal to the Y axis and 0 on those normal to the Z axis.
 
haruspex said:
I'm a bit confused about how you are assigning the axes.
I'll call the left right axis X, the vertical axis Z and the lower left/ upper right axis in the picture Y. From that and the text description, I would say the pipe is infinite in the X axis and width a in the other two. The voltage is V on the faces normal to the Y axis and 0 on those normal to the Z axis.
Sorry I missed that. y is the vertical axis.z is the axis coming out of the page. X is horizontal.

But I think it should be independent of Z since it is infinitely long. It mirrors an example straight out my textbook.
 
quittingthecult said:
z is the axis coming out of the page.
quittingthecult said:
independent of Z since it is infinitely long.
Looking at the diagram, the infinitely long direction is horizontal.
 

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