4.3.0.0.3 RK2:

A time-integrator that advances a field \bgroup\color{Green}$ \Phi$\egroupn at time n , to time n + 1 . For the ODE system

$\displaystyle {\frac{{d \mathbf{\Phi}}}{{d t}}}$ = F($\displaystyle \Phi$, t) (4.5)

it adopts the following algorithm
$\displaystyle \Phi$(1) = $\displaystyle \Phi$n + $\displaystyle \Delta$tF($\displaystyle \Phi$n, n$\displaystyle \Delta$t)   Stage 1  
$\displaystyle \Phi$n+1 = $\displaystyle \Phi$n + $\displaystyle {\frac{{\Delta t}}{{2}}}$$\displaystyle \left(\vphantom{ F(\mathbf{\Phi}^n, n
\Delta t) + F(\mathbf{\Phi}^{(1)}, (n+1) \Delta t) }\right.$F($\displaystyle \Phi$n, n$\displaystyle \Delta$t) + F($\displaystyle \Phi$(1),(n + 1)$\displaystyle \Delta$t)$\displaystyle \left.\vphantom{ F(\mathbf{\Phi}^n, n
\Delta t) + F(\mathbf{\Phi}^{(1)}, (n+1) \Delta t) }\right)$ (4.6)

Therefore, the integrator has no idea of the dimensionality of space, but makes copious use of the functionality in the FieldVar for the imposition of boundary conditions and ghost-cell updates.

2010-08-11