Section 26.7

Laplace's Equation

What does the heat distribution look like when it stops changing?

1

Introduction

In 2D, the steady state Heat Equation () becomes:

Solutions are called Harmonic Functions. They have the Mean Value Property.

2

Rectangular Domain

Solution Form

Assume . We get and .

One direction will have sines/cosines (to fit 0 BCs), the other will have or exponentials.

3

Worked Examples

Example 1: Top Edge Hot

Square plate. Left, Right, Bottom = 0. Top = .

X-direction has 0 BCs .

Y-direction has 0 at bottom .

.

Example 2: Symmetry

What if on top is ?

Only the term survives.

.

Find by setting .

Example 3: Visual Field

Isotherms curve away from the hot edge.

4

Practice Quiz

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