| 3 | | = Topography implementation = |
| | 3 | The topography implementation described in Sect. [wiki:/doc/tec/bc#Topography 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 |
| | 4 | horizontal grid in PALM, they can be directly incorporated into the standard loop structure of the Fortran code as lower vertical index |
| | 5 | 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. [wiki:/doc/tec/bc#Topography boundary conditions]): |
| | 6 | {{{ |
| | 7 | #!Latex |
| | 8 | \begin{itemize} |
| | 9 | \item[A.] \texttt{0 $\leq$ k} $<$ \texttt{nzb\_w\_inner}, grid points |
| | 10 | within obstacles or in the ground that are excluded from |
| | 11 | calculations, |
| | 12 | \item[B.] \texttt{nzb\_w\_inner} \texttt{$\leq$} \texttt{k} $<$ |
| | 13 | \texttt{nzb\_w\_outer}, grid points next to vertical walls, where |
| | 14 | wall-bounded code is executed, |
| | 15 | \item[C.] \texttt{k} $=$ \texttt{nzb\_w\_inner} $=$ |
| | 16 | \texttt{nzb\_w\_outer}, grid points next to horizontal walls, where |
| | 17 | wall-bounded code is executed, |
| | 18 | \item[D.] all other $k$, grid points in free fluid. |
| | 19 | \end{itemize} |
| | 20 | }}} |
| | 21 | The additional topography code is executed in regions B and C only. As the velocity components are defined on a different (staggered) grid |
| | 22 | than the scalar quantities (see Fig. 1 in Sect. [wiki:doc/tec/discret 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). |
