Changes between Version 6 and Version 7 of u/erica/PoissonSolver


Ignore:
Timestamp:
08/19/13 12:36:43 (11 years ago)
Author:
Erica Kaminski
Comment:

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  • u/erica/PoissonSolver

    v6 v7  
    55Elliptic equations can be thought of as being the steady state limit of the diffusion equation,
    66
    7 [[latex($u_t = (\kappa u_x)_x + (\kappa u_y)_y + \psi$)]]
     7[[latex($u_t = (\kappa u_x)_x + (\kappa u_y)_y + f$)]]
    88
    9 when both the 1) boundary conditions and 2) the source (or forcing term) [[latex($\psi$)]] are time-independent. Under these conditions, the time-dependent terms vanish as the system relaxes to steady state (in the limit t [[latex($\rightarrow \infty$)]]), and we are led to the elliptic equation (here in 2D),
     9when both the boundary conditions and the source (or "forcing") term  are time in-dependent. Under these conditions, the time dependent terms vanish as the system relaxes to steady state (in the limit t [[latex($\rightarrow \infty$)]]), and we are led to the elliptic equation (here in 2D),
    1010
    1111[[latex($(\kappa u_x)_x + (\kappa u_y)_y = f $)]]
    1212
    13 where u is the dependent variable we are solving for, and here f is the forcing term.
     13where u is the dependent variable we are solving for, and f is the forcing term.
    1414
    15 This equation needs to 1) be satisfied by all points within a bounding region and 2) satisfy the boundary conditions on that region. This then can be interpreted as an instantaneous constraint on the system, much different than the wave-like solutions of hyperbolic equations which travel with finite speed.
     15The solution to this equation needs to simultaneously 1) satisfy this equation at all points within a bounding region and 2) satisfy the boundary conditions on that region. This then can be interpreted as an instantaneous system, much different than the wave-like solutions of hyperbolic equations which travel with finite speed.
    1616
    17 Some special cases for elliptic equations are when [[latex($\kappa = 1$)]]. When f is non-zero, we have the Poisson equation,
     17Some special cases for elliptic equations occur when [[latex($\kappa = 1$)]]; when f is non-zero, we have the Poisson equation,
    1818
    1919[[latex($\triangledown ^2 u = f$)]]