57 |
interior of a fluid. Differences arise at boundaries where a boundary |
interior of a fluid. Differences arise at boundaries where a boundary |
58 |
is not positioned on a regular or smoothly varying grid. This method |
is not positioned on a regular or smoothly varying grid. This method |
59 |
is used to represent the topography using lopped cell, see |
is used to represent the topography using lopped cell, see |
60 |
\cite{Adcroft98}. Subtle difference also appear in more than one |
\cite{adcroft:97}. Subtle difference also appear in more than one |
61 |
dimension away from boundaries. This happens because the each |
dimension away from boundaries. This happens because the each |
62 |
direction is discretized independently in the finite difference method |
direction is discretized independently in the finite difference method |
63 |
while the integrating over finite volume implicitly treats all |
while the integrating over finite volume implicitly treats all |
64 |
directions simultaneously. Illustration of this is given in |
directions simultaneously. Illustration of this is given in |
65 |
\cite{Adcroft02}. |
\cite{ac:02}. |
66 |
|
|
67 |
\subsection{C grid staggering of variables} |
\subsection{C grid staggering of variables} |
68 |
|
|
79 |
The basic algorithm employed for stepping forward the momentum |
The basic algorithm employed for stepping forward the momentum |
80 |
equations is based on retaining non-divergence of the flow at all |
equations is based on retaining non-divergence of the flow at all |
81 |
times. This is most naturally done if the components of flow are |
times. This is most naturally done if the components of flow are |
82 |
staggered in space in the form of an Arakawa C grid \cite{Arakawa70}. |
staggered in space in the form of an Arakawa C grid \cite{arakawa:77}. |
83 |
|
|
84 |
Fig. \ref{fig:cgrid3d} shows the components of flow ($u$,$v$,$w$) |
Fig. \ref{fig:cgrid3d} shows the components of flow ($u$,$v$,$w$) |
85 |
staggered in space such that the zonal component falls on the |
staggered in space such that the zonal component falls on the |
400 |
\label{fig:hfacs} |
\label{fig:hfacs} |
401 |
\end{figure} |
\end{figure} |
402 |
|
|
403 |
\cite{Adcroft97} presented two alternatives to the step-wise finite |
\cite{adcroft:97} presented two alternatives to the step-wise finite |
404 |
difference representation of topography. The method is known to the |
difference representation of topography. The method is known to the |
405 |
engineering community as {\em intersecting boundary method}. It |
engineering community as {\em intersecting boundary method}. It |
406 |
involves allowing the boundary to intersect a grid of cells thereby |
involves allowing the boundary to intersect a grid of cells thereby |
524 |
The difference in approach between ocean and atmosphere occurs because |
The difference in approach between ocean and atmosphere occurs because |
525 |
of the direct use of the ideal gas equation in forming the potential |
of the direct use of the ideal gas equation in forming the potential |
526 |
energy conversion term $\alpha \omega$. The form of these conversion |
energy conversion term $\alpha \omega$. The form of these conversion |
527 |
terms is discussed at length in \cite{Adcroft01}. |
terms is discussed at length in \cite{adcroft:02}. |
528 |
|
|
529 |
Because of the different representation of hydrostatic balance between |
Because of the different representation of hydrostatic balance between |
530 |
ocean and atmosphere there is no elegant way to represent both systems |
ocean and atmosphere there is no elegant way to represent both systems |