Changes between Version 33 and Version 34 of u/erica/PoissonSolver


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Timestamp:
08/20/13 10:40:31 (11 years ago)
Author:
Erica Kaminski
Comment:

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  • u/erica/PoissonSolver

    v33 v34  
    2929The solutions to both Poisson's and Laplace's equations satisfy the Uniqueness theorem (see Griffith's E&M textbook). That is, if the solution satisfies the aforementioned 2 conditions, it is the ''unique'' solution to the equation.
    3030
    31 As is, Poisson's equation is set up to solve for f (be it charge density, or matter density, etc.) given some potential (e.g. electrical or gravitational, etc.). However, in most situations we have the opposite information about a system -- given the density, we seek the potential. This requires some numerical techniques for solving this 2nd order differential equation, especially for those systems that do not admit closed-form solutions.
     31As is, Poisson's equation is set up to solve for f (be it charge density, or matter density, etc.) given some u (e.g. potential- either electrical or gravitational, etc.). However, in most situations we have the opposite information about a system -- given the density, we seek the potential. This requires some numerical techniques for solving this 2nd order differential equation, especially for those systems that do not admit closed-form solutions.
    3232
    3333= Equation Discretization =
     
    8888= Poisson Equation Physical Meaning =
    8989
    90 While the interpretation of Laplace's equation and the harmonic functions are nice, the same does not seem to apply for the more general Poisson's equation. Instead, the solutions to Poisson's equation are called Green's functions, and they are stitched together out of the solutions to the homogenous part of the PDE (namely, Laplace's equation. Here are some references:
     90While the interpretation of Laplace's equation and the harmonic functions are nice, the same does not seem to apply for the more general Poisson's equation. Instead, the solutions to Poisson's equation are called Green's functions, and they are stitched together out of the solutions to the homogenous part of the PDE (namely, Laplace's equation). Here are some references:
     91
     92[http://www.math.osu.edu/~gerlach.1/math/BVtypset/node87.html constructing Green's functions]
     93
     94[http://farside.ph.utexas.edu/teaching/em/lectures/node31.html related to Poisson's equation]
    9195
    9296= Boundary Conditions =
     
    117121This also has a closed-form solution which I then used to check the code. It performed correctly.
    118122
    119 Here is the initial condition:
     123Here is the forcing function:
    120124
    121125[[Image(simpleInit.png, 40%)]]
     
    131135Lastly, I used a more complicated forcing function (refer to the reference). It also performed well.
    132136
    133 Here is the initial condition:
     137Here is the forcing function:
    134138
    135139[[Image(complexInit.png, 40%)]]
     
    139143[[Image(complexFinal.png, 40%)]]
    140144
    141 Attached to this page is the .out file for my program which shows the number of iterations until convergence for the different mesh sizes, and the max error of the final iteration.
     145'''Attached to this page is the .out file''' for my program which shows the number of iterations until convergence for the different mesh sizes, and the max error of the final iteration.
    142146
    143147
     
    150154
    151155= References =
     156
     157Here are some of my electronic references:
     158
     159- [https://en.wikipedia.org/wiki/Order_of_accuracy Order of accuracy]
     160
     161- [http://farside.ph.utexas.edu/teaching/em/lectures/node31.html Green's functions and Poisson's equation]
     162
     163- [http://www.math.osu.edu/~gerlach.1/math/BVtypset/node87.html Constructing Green's functions]
     164
     165- [http://www.rsmas.miami.edu/personal/miskandarani/Courses/MSC321/Projects/prjpoisson.pdf Exercises I followed for my Poisson solver]
     166
     167
     168- [http://hipacc.ucsc.edu/html/HIPACCLectures/lecture_source.pdf Poisson solver info]
     169
     170- [http://geo.mff.cuni.cz/~lh/GUCAS/PDEwPGI3.pdf more PS info]
     171
     172- [http://people.sc.fsu.edu/~jburkardt/presentations/jacobi_poisson_1d.pdf more PS info]
     173
     174- [http://jupiter.ethz.ch/~pjt/FORTRAN/Class6.pdf more PS info]
     175
     176(The .pdf's are also attached to this page, in case they get taken down)
     177
     178As far as books, I referenced:
     179
     180- Numerical Recipes in Fortran - chapter 19 on PDE's
     181
     182- Leveque's Finite Differences
     183