Example 11.21.  Find the electrical potential  [Graphics:Images/MathModelsMod_gr_88.gif]  in the disk  [Graphics:Images/MathModelsMod_gr_89.gif]  that satisfies the boundary values

            [Graphics:Images/MathModelsMod_gr_90.gif]  

[Graphics:Images/MathModelsMod_gr_91.gif]

            Figure 11.38  The potentials  [Graphics:Images/MathModelsMod_gr_106.gif]  and  [Graphics:Images/MathModelsMod_gr_107.gif].  

Explore Solution 11.21.

Construct the solution with a conformal mapping.  This example is similar to Example 11.8.

[Graphics:../Images/MathModelsMod_gr_108.gif]




[Graphics:../Images/MathModelsMod_gr_109.gif]

 

 

 

Use Mathematica to make a contour plot of the temperature.  For computational purposes we use the following formula   [Graphics:../Images/MathModelsMod_gr_110.gif].  

[Graphics:../Images/MathModelsMod_gr_111.gif]




[Graphics:../Images/MathModelsMod_gr_112.gif]

[Graphics:../Images/MathModelsMod_gr_113.gif]

 

 

 

The following commands will graph the contours as parametric curves.

[Graphics:../Images/MathModelsMod_gr_114.gif]




[Graphics:../Images/MathModelsMod_gr_115.gif]

 

 

 

[Graphics:../Images/MathModelsMod_gr_116.gif]




[Graphics:../Images/MathModelsMod_gr_117.gif]

Hence the electrical potential  [Graphics:../Images/MathModelsMod_gr_118.gif]  is harmonic in the disk |z| < 1 and has the desired boundary values.  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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