Example 11.8.  Find a function  [Graphics:Images/DirichletProblemMod_gr_203.gif]  that is harmonic in the unit disk  [Graphics:Images/DirichletProblemMod_gr_204.gif],  which takes on the boundary values

(11-8)            [Graphics:Images/DirichletProblemMod_gr_205.gif]  

Figure 11.8  The Dirichlet problems for [Graphics:Images/DirichletProblemMod_gr_220.gif] and [Graphics:Images/DirichletProblemMod_gr_221.gif].  

Explore Solution 11.8.

Construct the solution via a known conformal mapping.  This example is similar to Example 11.21.

[Graphics:../Images/DirichletProblemMod_gr_222.gif]




[Graphics:../Images/DirichletProblemMod_gr_223.gif]

 

 

 

The above solution is theoretical, it can be used for computations.  If the trigonometric identity  [Graphics:../Images/DirichletProblemMod_gr_224.gif]  is used we get a version that plots the boundary values better.  Then use Mathematica to make a contour plot of the solution.

[Graphics:../Images/DirichletProblemMod_gr_225.gif]





[Graphics:../Images/DirichletProblemMod_gr_226.gif]

[Graphics:../Images/DirichletProblemMod_gr_227.gif]

 

 

 

Next, use Mathematica to make a 3D plot of the solution.

[Graphics:../Images/DirichletProblemMod_gr_228.gif]





[Graphics:../Images/DirichletProblemMod_gr_229.gif]

[Graphics:../Images/DirichletProblemMod_gr_230.gif]

The function  [Graphics:../Images/DirichletProblemMod_gr_231.gif]  is harmonic in the unit disk  [Graphics:../Images/DirichletProblemMod_gr_232.gif],  and takes on the desired boundary values.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

(c) 2006 John H. Mathews, Russell W. Howell