Example 1.  Consider the heat equation where  [Graphics:Images/CrankNicolsonMod_gr_18.gif].   The length of the rod is  [Graphics:Images/CrankNicolsonMod_gr_19.gif].  Assume that the ends of the rod are held at the temperature  [Graphics:Images/CrankNicolsonMod_gr_20.gif].  Assume that the initial temperature distribution is

      [Graphics:Images/CrankNicolsonMod_gr_21.gif].
      
Apply the forward difference method with  [Graphics:Images/CrankNicolsonMod_gr_22.gif]  and  obtain temperature distributions for  [Graphics:Images/CrankNicolsonMod_gr_23.gif].
We will use  [Graphics:Images/CrankNicolsonMod_gr_24.gif] .  This forces  [Graphics:Images/CrankNicolsonMod_gr_25.gif].

Solution 1.

[Graphics:../Images/CrankNicolsonMod_gr_26.gif]


Now set up the table of solutions.

 

 

[Graphics:../Images/CrankNicolsonMod_gr_27.gif]

Next, solve it.

 

 

[Graphics:../Images/CrankNicolsonMod_gr_28.gif]
[Graphics:../Images/CrankNicolsonMod_gr_29.gif]


[Graphics:../Images/CrankNicolsonMod_gr_30.gif]

[Graphics:../Images/CrankNicolsonMod_gr_31.gif]

[Graphics:../Images/CrankNicolsonMod_gr_32.gif]

[Graphics:../Images/CrankNicolsonMod_gr_33.gif]

[Graphics:../Images/CrankNicolsonMod_gr_34.gif]
[Graphics:../Images/CrankNicolsonMod_gr_35.gif]
[Graphics:../Images/CrankNicolsonMod_gr_36.gif]
[Graphics:../Images/CrankNicolsonMod_gr_37.gif]


To see the numerical values enter the command:

[Graphics:../Images/CrankNicolsonMod_gr_38.gif]



[Graphics:../Images/CrankNicolsonMod_gr_39.gif]

[Graphics:../Images/CrankNicolsonMod_gr_40.gif]

[Graphics:../Images/CrankNicolsonMod_gr_41.gif]

[Graphics:../Images/CrankNicolsonMod_gr_42.gif]

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

(c) John H. Mathews 2004