| Version 3 (modified by Giersch, 9 years ago) (diff) |
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Topography implementation
The topography implementation described in Sect. boundary conditions allows the use of 2-D topography height data in PALM. Currently, the topography data has to be provided within a rastered ASCII file. After reading and mapping of these data to the horizontal grid in PALM, they can be directly incorporated into the standard loop structure of the Fortran code as lower vertical index for all integration loops. Therefore, PALM employs two 2-D height index arrays (e.g., nzb_w_inner(j, i) and nzb_w_outer(j, i) for the velocity component w) to separate the domain into four regions based on the vertical index k (see Fig. 4 in Sect. boundary conditions):
![\begin{itemize}
\item[A.] \texttt{0 $\leq$ k} $<$ \texttt{nzb\_w\_inner}, grid points
within obstacles or in the ground that are excluded from
calculations,
\item[B.] \texttt{nzb\_w\_inner} \texttt{$\leq$} \texttt{k} $<$
\texttt{nzb\_w\_outer}, grid points next to vertical walls, where
wall-bounded code is executed,
\item[C.] \texttt{k} $=$ \texttt{nzb\_w\_inner} $=$
\texttt{nzb\_w\_outer}, grid points next to horizontal walls, where
wall-bounded code is executed,
\item[D.] all other $k$, grid points in free fluid.
\end{itemize}](/trac/tracmath/51c939794396b365677a5f953f1d9decb01a2036.png)
The additional topography code is executed in regions B and C only. As the velocity components are defined on a different (staggered) grid than the scalar quantities (see Fig. 1 in Sect. discretization), three extra pairs of 2-D height index arrays are defined; two for the horizontal velocities and one for scalar quantities (e.g., nzb_s_inner and nzb_s_outer for scalar quantities).
