source: palm/trunk/TUTORIAL/SOURCE/topography.tex @ 1033

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1%$Id: topography.tex 973 2012-08-07 16:03:47Z letzel $
2\input{header_tmp.tex}
3%\input{../header_lectures.tex}
4
5\usepackage[utf8]{inputenc}
6\usepackage{ngerman}
7\usepackage{pgf}
8\usetheme{Dresden}
9\usepackage{subfigure}
10\usepackage{units}
11\usepackage{multimedia}
12\usepackage{hyperref}
13\newcommand{\event}[1]{\newcommand{\eventname}{#1}}
14\usepackage{xmpmulti}
15\usepackage{tikz}
16\usetikzlibrary{shapes,arrows,positioning,decorations.pathreplacing}
17\def\Tiny{\fontsize{4pt}{4pt}\selectfont}
18
19%---------- neue Pakete
20\usepackage{amsmath}
21\usepackage{amssymb}
22\usepackage{multicol}
23\usepackage{pdfcomment}
24\usepackage{xcolor}
25
26\institute{Institut fÌr Meteorologie und Klimatologie, Leibniz UniversitÀt Hannover}
27\date{last update: \today}
28\event{PALM Seminar}
29\setbeamertemplate{navigation symbols}{}
30\setbeamersize{text margin left=.5cm,text margin right=.2cm}
31\setbeamertemplate{footline}
32  {%
33    \begin{beamercolorbox}[rightskip=-0.1cm]&
34     {\includegraphics[height=0.65cm]{imuk_logo.pdf}\hfill \includegraphics[height=0.65cm]{luh_logo.pdf}}
35    \end{beamercolorbox}
36    \begin{beamercolorbox}[ht=2.5ex,dp=1.125ex,%
37      leftskip=.3cm,rightskip=0.3cm plus1fil]{title in head/foot}%
38      {\leavevmode{\usebeamerfont{author in head/foot}\insertshortauthor} \hfill \eventname \hfill \insertframenumber \; / \inserttotalframenumber}%
39    \end{beamercolorbox}%
40%    \begin{beamercolorbox}[colsep=1.5pt]{lower separation line foot}%
41%    \end{beamercolorbox}
42  }%\logo{\includegraphics[width=0.3\textwidth]{luhimuk_logo.eps}}
43
44\title[PALM - Using Topography]{PALM - Using Topography}
45\author{Siegfried Raasch}
46
47% Notes:
48% jede subsection bekommt einen punkt im menu (vertikal ausgerichtet.
49% jeder frame in einer subsection bekommt einen punkt (horizontal ausgerichtet)
50\begin{document}
51% Folie 1
52\begin{frame}
53\titlepage
54\end{frame}
55
56% Folie 2
57\begin{frame}
58   \frametitle{Contents – Using Topography (I)}
59   \begin{itemize}
60      \item{Purpose of topography in PALM} 
61      \item{Definition}
62      \item{Realization}
63      \begin{itemize}
64         \item{Physical concept}
65         \item{Technical / numerical implementation}
66      \end{itemize}
67      \item{Strengths and limitations}
68      \item{Control parameters}
69      \begin{itemize}
70         \item{Required / optional topography parameters}
71         \item{Topography-related general control parameters}
72         \begin{itemize}
73            \item{Suitable driving methods, initial and boundary conditions}
74            \item{Pressure solver}
75         \end{itemize}
76      \end{itemize}
77      \item{Data output}
78   \end{itemize}
79\end{frame}
80
81% Folie 3
82\begin{frame}
83   \frametitle{Purpose of Topography}
84   \begin{itemize}
85      \item{Optional feature to simulate flow around/above obstacles}
86      \par\bigskip
87      \item{Application fields}
88      \begin{itemize}
89         \item{Urban meteorology, wind engineering}
90         \item{Mesoscale meteorology}
91         \item{Oceanography}
92         \item{...}
93      \end{itemize} 
94   \end{itemize}
95\end{frame}
96
97% Folie 4
98\begin{frame}
99   \frametitle{Definition}   
100   \begin{itemize}
101      \item{The topography definition in PALM covers solid, impermeable, fixed flow obstacles with a volume of at least one grid box.}
102      \par\bigskip
103      \item{The following qualifies as topography: \textcolor{green!50!black!100}{\checkmark}}     
104      \begin{itemize}
105         \footnotesize
106         \item{Human-made obstacles (buildings)}
107         \item{Natural obstacles (hills, mountains)}
108      \end{itemize}
109      \par\bigskip
110      \item{The following does NOT qualify as topography: \textcolor{red}{$\times$}}
111      \begin{itemize}
112         \footnotesize
113         \item{\begin{tabbing}Permeable obstacles (vegetation) $\}$  \= Parameterization options in PALM: \\
114                                                                     \> canopy model, local roughness length  \end{tabbing} } 
115         \item{Small obstacles (signposts)}
116         \item{Moving obstacles (vehicles)}                                                   
117      \end{itemize}
118   \end{itemize}
119\end{frame}
120
121% Folie 5
122\begin{frame}
123   \frametitle{Realization - Physical Concept}
124   \scriptsize
125   \begin{columns}[c]
126   \column{0.8\textwidth}
127      \begin{itemize}
128         \item{Flow cannot enter topography and is forced around/above it.}
129      \end{itemize}
130   \column{0.2\textwidth}
131   \end{columns}
132   \begin{columns}[c]
133   \column{0.6\textwidth}
134      \begin{itemize}
135         \item{Grid boxes are}
136         \begin{itemize}
137            \item{\begin{minipage}{0.1\textwidth} 
138                     \includegraphics[width=0.7\textwidth]{topography_figures/physical_concept_small1.png}
139                  \end{minipage}
140                  \begin{minipage}{0.5\textwidth} \scriptsize
141                     \par\medskip
142                     100\% free fluid, \\
143                  \end{minipage}}
144            \item{\begin{minipage}{0.1\textwidth}
145                     \includegraphics[width=0.7\textwidth]{topography_figures/physical_concept_small2.png}
146                  \end{minipage}
147                  \begin{minipage}{0.5\textwidth} \scriptsize
148                     100\% fluid adjacent to an obstacle, or
149                  \end{minipage}}     
150            \item{\begin{minipage}{0.1\textwidth} 
151                     \includegraphics[width=0.7\textwidth]{topography_figures/physical_concept_small3.png}
152                  \end{minipage}
153                  \begin{minipage}{0.5\textwidth} \scriptsize
154                     \par\medskip
155                     100\% obstacle. \\
156                  \end{minipage}}             
157         \end{itemize}
158         \item{No-slip boundary condition}
159         \begin{itemize}
160            \item{\scriptsize Wall-normal velocity component is zero at obstacle surface \textbf{\textcolor{blue}{---------}}}
161         \end{itemize}
162         \par\bigskip
163         \item{\begin{minipage}{0.75\textwidth}  \scriptsize
164                  Local surface layer for the first grid box \\adjacent to each obstacle surface
165               \end{minipage}
166               \begin{minipage}{0.1\textwidth}
167                  \includegraphics[width=0.7\textwidth]{topography_figures/physical_concept_small2.png}
168               \end{minipage}}
169         \par\smallskip
170         \begin{itemize}
171            \item{\scriptsize Neutral Monin-Obukhov similarity}
172         \end{itemize}
173      \end{itemize}
174   \column{0.4\textwidth}
175      \includegraphics[width=\textwidth]{topography_figures/physical_concept.png}
176   \end{columns}
177\end{frame}
178
179% Folie 6
180\begin{frame}
181   \frametitle{Realization - \\ Numerical /Technical Implementation (I)}
182   \small
183   \begin{columns}[c]
184   \column{0.5\textwidth}
185      \begin{itemize}
186         \item{Obstacles must be surface-mounted}
187         \item{Overhanging structures \textcolor{blue}{$\times$}, holes \textcolor{red}{$\times$} etc. are not permitted.}
188         \begin{itemize}
189            \footnotesize
190            \item{This simplification allows extra performance optimization by reducing the 3D obstacle dimension to a "'2.5D"' dimension.}
191            \item{"'2.5D"' means that each horizontal grid cell is assigned only one height level.}
192            \item{This conforms to the "'2.5D"' format of Digital Elevation Models (DEM).}
193         \end{itemize}
194      \end{itemize}     
195   \column{0.4\textwidth}
196      \par\medskip
197      \includegraphics[width=1.1\textwidth]{topography_figures/technical_implementation.png}
198   \end{columns}
199\end{frame}
200
201% Folie 7
202\begin{frame}
203   \frametitle{Realization - \\ Numerical /Technical Implementation (II)}
204   \begin{columns}[c]
205   \column{0.4\textwidth}
206      \footnotesize     
207      The location of the wall-normal velocity component defines the location of the impermeable obstacle surface. \\
208      \par\smallskip
209      Obstacle surfaces that do not match the grid are approximated by grid boxes like a step-function.
210      \par\bigskip
211      $\bullet$ scalars \\
212      \textcolor{red}{$\bullet$ u (staggered)} \\
213      \textcolor{green!40!black!100}{\textbf{+} v (staggered)}
214%      \includegraphics[width=0.4\textwidth]{topography_figures/technical_implementation_grid/technical_implementation_grid_small1.png} \\
215%      \includegraphics[width=0.6\textwidth]{topography_figures/technical_implementation_grid/technical_implementation_grid_small2.png} \\
216%      \includegraphics[width=0.6\textwidth]{topography_figures/technical_implementation_grid/technical_implementation_grid_small3.png}
217   \column{0.6\textwidth}
218      \includegraphics<1>[width=\textwidth]{topography_figures/technical_implementation_grid/technical_implementation_grid_1.png}
219      \includegraphics<2>[width=\textwidth]{topography_figures/technical_implementation_grid/technical_implementation_grid_2.png}
220      \includegraphics<3>[width=\textwidth]{topography_figures/technical_implementation_grid/technical_implementation_grid_3.png}
221      \includegraphics<4>[width=\textwidth]{topography_figures/technical_implementation_grid/technical_implementation_grid_4.png}
222      \includegraphics<5>[width=\textwidth]{topography_figures/technical_implementation_grid/technical_implementation_grid_5.png}
223   \end{columns}
224\end{frame}
225
226% Folie 8
227\begin{frame}
228   \frametitle{Realization - \\ Numerical / Technical Implementation (III)}
229   \footnotesize
230   \textbf{Rastering GIS data: \dq from GIS data to ASCII raster data\dq}
231   \begin{itemize}
232      \item{In order to process topography from external data sources, the data must be made available
233            to PALM as a rastered ASCII file, e.g. example\_topo.} 
234      \item{The layout of example\_topo must conform to the computational domain size and to the grid size dx and dy.}
235      \item{The rastered height data of example\_topo are given in m above ground and do not need to match
236            the vertical grid, since they are interpolated.}
237      \par\bigskip
238      \item{Software known to be able to perfom the rastering process of GIS data in vector and/or raster format to PALM raster format:}
239      \begin{itemize}
240         \item{ArcGIS (commercial)}
241         \item{GRASS GIS (freeware)}
242         \item{...? (please report to us)}
243      \end{itemize}
244   \end{itemize}
245\end{frame}
246
247% Folie 9
248\begin{frame}
249   \frametitle{Realization – \\ Numerical / Technical Implementation (IV)} 
250   \small
251   \textbf{Potential issues}
252   \begin{itemize}
253      \item{Load imbalance} 
254      \begin{itemize}
255         \item{Leads to inefficient parallelization: \dq fast\dq CPU(s) must wait for \dq slow\dq CPU(s)}
256         \item{Occurs if the CPUs do not share the same workload}
257         \begin{itemize}
258            \item{E.g. if topography is significantly heterogeneous in a large volume fraction of the computational domain}
259         \end{itemize}
260      \end{itemize}     
261      \item{\dq 2 $\Delta$x\dq instabilities}
262      \begin{itemize}
263         \item{Upstream of obstacle walls}
264         \item{Due to second-order finite difference advection scheme}
265         \item{Model remains stable throughout the simulation}
266      \end{itemize}
267   \end{itemize}
268\end{frame}
269
270% Folie 10
271\begin{frame}
272   \frametitle{Summary: Strengths (+) and Limitations (–)}
273   \small
274   \begin{itemize}
275      \item[+]{Horizontal and vertical surfaces can be exactly resolved (thanks to the finite difference Cartesian model architecture)}
276      \item[+]{Optimization also for scalar computer architectures}
277      \item[+]{Conforms with \dq 2.5D\dq format of Digital Elevation Models (DEM)} 
278      \par\bigskip
279      \item[-]{Obstacles must be surface-mounted}
280      \item[-]{Grid boxes can only be 100\% fluid or 100\% obstacle \\ \par\smallskip
281              \begin{footnotesize} Obstacle surfaces that do not match the grid are approximated by grid boxes like a step-function, which
282              modifies the real obstacle size \end{footnotesize}}
283      \item[-]{Overhanging structures, holes etc. are not permitted due to the \dq 2.5D\dq format}
284   \end{itemize}
285\end{frame}
286
287% Folie 11
288\begin{frame}
289   \frametitle{Take a Short Break... Urban Flow Visualization}
290   \begin{columns}[c]
291   \column{0.42\textwidth}
292      \includegraphics<1>[width=\textwidth]{topography_figures/hannover_1.png}
293      \href{.html}{\includegraphics<2>[width=\textwidth]{topography_figures/hannover_2.png}}
294   \column{0.58\textwidth}
295      Set-up: neutral boundary layer
296      \begin{itemize}
297         \item{Particle = passive tracer}
298         \item{Colour $\sim$ particle height}
299         \item{Tail length ~ particle velocity}         
300      \end{itemize}     
301      \par\bigskip
302      \begin{itemize}
303         \item{Flow past office tower:}
304         \begin{itemize}
305            \item{initially laminar: not yet an LES}
306            \item{intermittent: different episodes}
307         \end{itemize}
308         \item{Broad street canyon flow:}
309         \begin{itemize}
310            \item{channeling}
311            \item{low-level upstream flow}
312         \end{itemize}
313      \end{itemize}
314   \end{columns}
315\end{frame}
316
317% Folie 12
318\begin{frame}
319   \frametitle{Required Topography Control Parameters}
320    \footnotesize
321   {\tt topography =} 
322   \begin{itemize}
323      \item{{\tt 'flat'} \hspace{3cm} no topography (default)}
324      \item{{\tt 'single\_building'} \hspace{1.2cm} \textcolor{red}{generic} single building} 
325      \item{{\tt 'single\_street\_canyon'} \hspace{0.4cm} \textcolor{red}{generic} single quasi-2D street canyon}
326      \item{{\tt 'read\_from\_file'} \hspace{1.4cm} \textcolor{blue}{rastered} ASCII file, e.g. {\tt example\_topo}}
327      \item{any other string \hspace{1.8cm} processed by user subroutine user\_init\_grid}
328   \end{itemize}
329   {\tt topography\_grid\_convention =}
330   \begin{itemize}
331      \item{{\tt '\textcolor{red}{cell\_edge}'} \hspace{2.2cm} default for \textcolor{red}{generic} topography: \textcolor{red}{$\leftrightarrow$}}
332      \item{{\tt '\textcolor{blue}{cell\_center}'} \hspace{1.9cm} default for \textcolor{blue}{rastered} topography: \textcolor{blue}{$\bigcirc$ $\leftrightarrow$}} 
333   \end{itemize}
334   \includegraphics<1>[width=0.5\textwidth]{topography_figures/control_parameters_1.png}
335   \includegraphics<2>[width=0.5\textwidth]{topography_figures/control_parameters_2.png}
336   \includegraphics<3>[width=0.5\textwidth]{topography_figures/control_parameters_3.png}
337   \includegraphics<4>[width=0.5\textwidth]{topography_figures/control_parameters_4.png}
338\end{frame}
339
340% Folie 13
341\begin{frame}
342   \frametitle{Optional Topography Control Parameters (I)}
343   \small
344   \textbf{Generic topography}   
345   \scriptsize
346   \begin{itemize}
347      \item{topography = {\tt 'single\_building'}} 
348      \begin{itemize}
349         \scriptsize
350         \item{building\_height = 50.0 \hspace{0.67cm} height of the building}
351         \item{building\_length\_x = 50.0 \hspace{0.43cm} length of the building in x-direction}
352         \item{building\_length\_y = 50.0 \hspace{0.43cm} length of the building in y-direction}
353         \item{building\_wall\_left \hspace{1.4cm} (default is building centered in x-direction)}
354         \item{building\_wall\_south \hspace{1.13cm} (default is building centered in y-direction)}
355      \end{itemize}
356      \item{topography = {\tt 'single\_street\_canyon'}}
357      \begin{itemize}
358         \scriptsize
359         \item{canyon\_height = 50.0 \hspace{0.45cm} height of the canyon \\
360               and}
361         \item{canyon\_width\_x = 50.0 \hspace{0.3cm} implies canyon axis orientation in y-direction}
362         \item{canyon\_wall\_left \hspace{1.17cm} (default is canyon centered in x-direction) \\
363               or}
364         \item{canyon\_width\_y = 50.0 \hspace{0.3cm} implies canyon axis orientation in x-direction}
365         \item{canyon\_wall\_south \hspace{0.9cm} (default is canyon centered in y-direction)}
366      \end{itemize}
367   \end{itemize}
368\end{frame}
369
370% Folie 14
371\begin{frame}
372   \frametitle{Optional Topography Control Parameters (II)}
373   \scriptsize   
374   \textbf{Rastered topography}\\
375   \begin{minipage}{0.7\textwidth}
376      \begin{itemize}
377         \scriptsize
378         \item{{\tt topography} = 'read\_from\_file'} 
379         \begin{itemize}
380            \footnotesize
381            \item{requires an external ASCII file, e.g. {\tt example\_topo:}}
382         \end{itemize}
383      \end{itemize}
384   \end{minipage}
385   \begin{minipage}{0.2\textwidth}
386      \includegraphics[width=0.5\textwidth]{topography_figures/optional_control_parameters_1.png}
387   \end{minipage}
388   \begin{center}
389      \includegraphics[width=0.85\textwidth]{topography_figures/optional_control_parameters_2.png}
390   \end{center}
391   \begin{itemize}
392      \item[]{}
393      \begin{itemize} 
394         \scriptsize         
395         \item{layout must conform to domain size and grid size dx and dy.}
396         \item{height data}
397         \begin{itemize}
398            \scriptsize
399            \item{in m above ground (INTEGER or REAL)}
400            \item{do not need to match the vertical grid}
401         \end{itemize}
402      \end{itemize}
403   \end{itemize}
404\end{frame}
405
406% Folie 15
407\begin{frame}
408   \frametitle{Optional Topography Control Parameters (III)}
409   \small
410   \textbf{Rastered topography}
411   \begin{itemize}
412      \item{{\tt topography} = 'read\_from\_file'}
413      \par\smallskip
414      \begin{itemize}
415         \item{\textbf{mrun}-call: \\
416               {\tt mrun ... -r 'd3\# ...'}}
417         \par\medskip
418         \item{{\tt .mrun.config:}}
419      \end{itemize}
420   \end{itemize} 
421   \begin{center} \includegraphics[width=0.7\textwidth]{topography_figures/optional_control_parameters_3.png} \end{center}
422\end{frame}
423
424% Folie 16   
425\begin{frame}
426   \frametitle{General Control Parameters (I): Suitable Driving Methods}
427   \scriptsize
428   \begin{itemize}
429      \item{\textbf{\dq Meteorological\dq set-up M: geostrophic wind / Coriolis force}}
430      \begin{itemize}
431         \scriptsize
432         \item{Set {\tt omega $ \neq$ 0.0}}
433         \item{Construct a non-zero profile of geostrophic wind $u_g$ and/or $v_g$ using {\tt ug\_surface}, {\tt ug\_vertical\_gradient}
434               and {\tt ug\_vertical\_gradient\_level} and/or the respective parameter set for $v_g$}
435      \end{itemize}
436      \par\bigskip
437      \item{\textbf{\dq Engineering\dq set-up E: direct external pressure gradient / no Coriolis force}}
438      \begin{itemize}
439         \scriptsize
440         \item{Set {\tt omega = 0.0}}
441         \item{Set-up E1: direct external pressure gradient that does not change with time
442                 (the bulk velocity fluctuates with time)}
443         \begin{itemize}
444            \scriptsize
445            \item{Parameters: {\tt dp\_external}, {\tt dp\_smooth}, {\tt dp\_level\_b}, {\tt dpdxy}}
446         \end{itemize}
447         \item{Set-up E2: maintain a constant bulk velocity
448                 (the direct external pressure gradient fluctuates with time)}
449         \begin{itemize}
450             \scriptsize
451             \item{Parameters: {\tt conserve\_volume\_flow}, {\tt conserve\_volume\_flow\_mode}, {\tt u\_bulk}, {\tt v\_bulk}}
452         \end{itemize}
453      \end{itemize}
454      \par\bigskip
455      \item{\textbf{\dq Thermal\dq set-up T: directly prescribe sensible heatflux}}
456      \begin{itemize}
457         \item[]{}
458         \begin{itemize}
459            \scriptsize
460            \item{surface\_heatflux at ground level only} 
461            \item{wall\_heatflux(0:4) at top/left/right/South/North obstacle face}
462         \end{itemize}
463      \end{itemize}
464   \end{itemize}
465\end{frame}
466
467% Folie 17
468\begin{frame}
469   \frametitle{General Control Parameters (II): Initialization}
470   \scriptsize
471   \begin{itemize}
472      \item{\textbf{\dq Meteorological\dq set-up M }\\
473            Initialize a non-zero profile of geostrophic wind $u_g$ and/or $v_g$ using}
474      \begin{itemize}
475         \scriptsize
476         \item{{\tt initializing\_actions =} \textbf{'set\_constant\_profiles' (e.g. for convective BL)}}
477         \begin{itemize}
478            \scriptsize
479            \item{Parameters: {\tt ug\_surface $ \neq $ 0.0} and/or {\tt vg\_surface $\neq $ 0.0}}
480         \end{itemize}
481         \item{{\tt initializing\_actions =} \textbf{'set\_1d-model\_profiles' (e.g. for neutral BL)}}
482         \begin{itemize}
483            \scriptsize
484            \item{1D model prerun parameters with suffix {\tt \_1d} (e.g. {\tt end\_time\_1d}, {\tt damp\_level\_1d)}}
485         \end{itemize}
486      \end{itemize} 
487      \par\bigskip
488      \item{\textbf{\dq Engineering\dq set-up E} \\
489            Good initialization may require a priori knowlegde, e.g. from previous test runs.
490            Here, {\tt ug\_}... and {\tt vg\_}... don't refer to geostrophic wind but to the initial wind profile.} 
491      \begin{itemize}
492         \scriptsize
493         \item{{\tt initializing\_actions} = \textbf{'set\_constant\_profiles'}}
494         \begin{itemize}
495            \scriptsize
496            \item{Parameter set: {\tt ug\_surface}, {\tt ug\_vertical\_gradient}[{\tt \_level}] and/or the respective set for $v_g$}
497         \end{itemize}
498         \item{{\tt initializing\_actions} = \textbf{'set\_1d-model\_profiles'}}
499         \item{{\tt initializing\_actions} = \textbf{'by\_user' – processed by user\_init\_3d\_model}}
500      \end{itemize}
501      \par\bigskip
502      \item{\textbf{\dq Thermal\dq set-up T} \\
503            Any of the above may apply}
504   \end{itemize}
505\end{frame}
506
507% Folie 18
508\begin{frame}
509   \frametitle{General Control Parameters (III): Boundary Conditions}
510   \footnotesize
511   \begin{itemize}
512      \item{Lateral boundary conditions}
513      \begin{itemize}
514         \item{Cyclic / non-cyclic: cf. lecture on \dq non-cyclic boundary conditions\dq}
515      \end{itemize} 
516      \item{Bottom boundary conditions}
517      \begin{itemize}
518         \item{Cf. lecture on \dq numerics and boundary conditions\dq}
519      \end{itemize}
520      \item{Top boundary conditions}
521      \begin{itemize}
522         \footnotesize
523         \item{\textbf{Channel}: {\tt bc\_uv\_t =} \textbf{'dirichlet\_0' (no-slip)}}
524         \item{\textbf{Open channel}: {\tt bc\_uv\_t =} \textbf{'neumann' (slip)}}
525         \item{\textbf{\dq Constant flux\dq layer} (not yet published): {\tt bc\_uv\_t =} \textbf{'neumann' (slip)} \\
526                with set-up E1 where {\tt dp\_level\_b >> 0} and {\tt dp\_smooth = .T.}}
527      \end{itemize}
528   \end{itemize}
529\end{frame}
530
531% Folie 19
532\begin{frame}
533   \frametitle{General Control Parameters (IV): Pressure Solver} 
534   {\tt psolver =}
535   \par\medskip
536   \begin{itemize}
537      \item{'poisfft' (FFT scheme)} 
538      \begin{itemize}
539         \item{Good performance for urban PALM version}
540         \item{Cannot be used with non-cyclic boundary conditions}
541      \end{itemize}
542      \par\bigskip
543      \item{'multigrid' (Multigrid scheme)}
544      \begin{itemize}
545         \item{Performance for very large number of grid points may be better than FFT}
546         \item{This is the only possible choice for non-cyclic boundary conditions}
547      \end{itemize}
548   \end{itemize}
549\end{frame}
550
551% Folie 20
552\begin{frame}
553   \frametitle{Data Analysis / Output – Some Considerations (I)}
554   \scriptsize
555   \begin{itemize}
556      \item{How to get turbulence statistics?}
557      \begin{itemize}
558         \scriptsize
559         \item{Phase averaging if a direction of homogeneity exists}
560         \item{Temporal averaging}
561         \item{Ensemble averaging}
562      \end{itemize} 
563      \item{Definition of turbulent fluctuations}\\
564      \textbf{Spatial fluctuations:} deviation from representative instantaneous spatial average
565      \begin{itemize}
566         \scriptsize
567         \item{PALM: many statistics calculated on-the-fly as time series, 1D vertical profiles}
568         \item{Not suitable for topography unless a direction of homogeneity exists}
569      \end{itemize}
570      \textbf{Temporal fluctuations}: deviation from representative local temporal average
571      \begin{itemize}
572         \scriptsize
573         \item{Suitable for all applications including topography}
574         \item{Requires much hard disk space and post-processing CPU time}
575         \item{PALM: not natively supported, but following procedure works:}
576         \begin{itemize}
577            \scriptsize
578            \item{Collect time-series during the simulation (2D/3D data output or user-defined time series)}
579            \item{Check for (quasi-)steady turbulent state and sufficient averaging time}
580            \item{Calculate statistics by post-processing making use of the Reynolds decomposition: \\ \par\medskip
581                  $\overline{w'\theta'} = \overline{w\theta} - \overline{w} \overline{\theta} $}
582         \end{itemize}
583      \end{itemize}   
584   \end{itemize}
585\end{frame}
586
587% Folie 21
588\begin{frame}
589   \frametitle{Your Responsibility and Contribution}
590   \footnotesize
591   \par\medskip
592   In most cases, a new parameter is added to PALM for one specific purpose.
593   \par\bigskip
594   Beyond this one purpose, each new parameter normally gives many other new feature/parameter combinations in PALM.
595   We are unable to check all these combinations by ourselves and rely on your help!
596   \par\bigskip
597   For example, the combination of topography and non-cyclic lateral boundary conditions has not yet been tested
598   because both features have originally been introduced separately for different research projects.
599   \par\bigskip 
600   Therefore, we ask you for your responsibility and contribution:
601   \begin{itemize}
602      \item{Please always check your PALM setup carefully. PALM is not a black box.} 
603      \item{For example, design a simple case and test your expectation.}
604      \item{Please report potential bugs – thank you!}
605      \begin{itemize}
606         \item{PALM developer team}
607         \item{PALM user community (via trac-system)}
608      \end{itemize}
609   \end{itemize}
610\end{frame}
611
612% Folie 22
613\begin{frame}
614   \Large
615   \begin{center} \textcolor{blue!90!black!100}{Topography - Scenario examples} \end{center}
616\end{frame}
617
618% Folie 23
619\begin{frame}
620   \frametitle{Set-up Scenario: Single Street Canyon (I)}
621   \par\smallskip
622   \textbf{Single quasi-2D street canyon in neutral open channel flow with constant bulk velocity}
623   \par\smallskip
624   \begin{itemize}
625      \item{{\tt trunk/EXAMPLES/canyon/}}
626      \begin{itemize}
627         \item{Parameter file \hspace{2cm} {\tt example\_canyon\_p3d}}
628         \item{Run-control file \hspace{1.78cm} {\tt example\_canyon\_rc}}
629         \item{Some documentation \hspace{0.95cm} {\tt example\_canyon.odt}}
630      \end{itemize}
631   \end{itemize}
632   \begin{center}
633      \includegraphics[width=0.85\textwidth]{topography_figures/scenario_ssc_1.png}
634   \end{center}
635\end{frame}
636
637% Folie 24
638\begin{frame}
639   \frametitle{Set-up Scenario: Single Street Canyon (II)}
640   \textbf{The phase average makes use of homogeneity in y-direction:} \\
641   {\tt section\_xz = -1}, {\tt data\_output = \textbf{'u\_xz\_av'}}, {\tt 'v\_xz\_av'}, {\tt 'w\_xz\_av'}
642   \begin{center}
643      \includegraphics[width=0.85\textwidth]{topography_figures/scenario_ssc_2.png}
644   \end{center}
645\end{frame}
646
647% Folie 25
648\begin{frame}
649 \begin{tikzpicture}[remember picture, overlay]
650      \node [shift={(6.5 cm, 5cm)}]  at (current page.south west)
651         {%
652         \begin{tikzpicture}[remember picture, overlay]
653            \uncover<1>{\node at (0,-0.5) {\includegraphics[width=0.7\textwidth]{topography_figures/scenario_ssc_example_1.png}};}
654            \uncover<2>{\node at (0,-0.5) {\includegraphics[width=0.7\textwidth]{topography_figures/scenario_ssc_example_2.png}};}
655            \uncover<3->{\node at (0,-0.5) {\includegraphics[width=0.7\textwidth]{topography_figures/scenario_ssc_example_3.png}};}
656            \uncover<4->{\node at (-3.5,-0.2) {\includegraphics[width=0.48\textwidth]{topography_figures/scenario_ssc_example_4.png}};}
657            \uncover<5->{\node at (3.5,-0.2) {\includegraphics[width=0.38\textwidth]{topography_figures/scenario_ssc_example_5.png}};}
658         \end{tikzpicture}
659         };
660  \end{tikzpicture}
661\end{frame}
662
663% Folie 26
664\begin{frame}
665   \frametitle{Set-up Scenario: Constant Flux Layer}
666   \small
667   \textbf{Single surface-mounted cube in neutral open channel flow with a constant flux layer}
668   \begin{itemize}
669      \item{{\tt trunk/EXAMPLES/constant\_flux\_layer/}}
670      \begin{itemize}
671         \footnotesize
672         \item{Parameter file \hspace{2cm} {\tt example\_constant\_flux\_layer\_p3d}}
673         \item{Run-control file \hspace{1.79cm} {\tt example\_constant\_flux\_layer\_rc}}
674         \item{Some documentation \hspace{1.02cm} {\tt example\_constant\_flux\_layer.odt}}
675      \end{itemize}
676   \end{itemize}
677   \begin{center}
678      \includegraphics[width=0.85\textwidth]{topography_figures/scenario_cfl.png}
679   \end{center}
680\end{frame}
681
682% Folie 27
683\begin{frame}
684 \begin{tikzpicture}[remember picture, overlay]
685      \node [shift={(6.5 cm, 5cm)}]  at (current page.south west)
686         {%
687         \begin{tikzpicture}[remember picture, overlay]
688            \uncover<1->{\node at (0,-0.5) {\includegraphics[width=0.7\textwidth]{topography_figures/scenario_cfl_example_1.png}};}
689            \uncover<2->{\node at (-3.5,-0.2) {\includegraphics[width=0.45\textwidth]{topography_figures/scenario_cfl_example_2.png}};}
690            \uncover<3->{\node at (3.5,-0.2) {\includegraphics[width=0.38\textwidth]{topography_figures/scenario_cfl_example_3.png}};}
691         \end{tikzpicture}
692         };
693  \end{tikzpicture}
694\end{frame}
695
696% Folie 28
697\begin{frame}
698   \frametitle{Rules of Good Practise}
699   \small
700   \begin{itemize}
701      \item{If you run PALM with topography, make sure that it is really LES...}
702      \begin{itemize}
703         \item{''Large eddies'' are ''small'' between obstacles}
704         \begin{itemize}
705            \item{use fine grid length to resolve turbulence there}
706         \end{itemize}
707         \item{Ratio of resolved to SGS fluxes}
708      \end{itemize} 
709      \item{Check for (quasi-)steady turbulent state and sufficient averaging time.}
710      \begin{itemize}
711         \item{Fluctuations of time series of E, E*, maximum velocity components etc.}
712      \end{itemize}
713      \item{Make sure that your PALM result is independent of numerical parameters such as domain size and grid size.}
714      \begin{itemize}
715         \item{Sensitivity studies}
716      \end{itemize}
717      \item{If you intend to do a comparison with some kind of reference data, it is essential to configure the set-up of PALM
718           in the same way as the reference experiment.}
719      \begin{itemize}
720         \item{For example, if you compare PALM with wind tunnel results, you have to follow the wind tunnel set-up for setting up PALM.}
721      \end{itemize}
722   \end{itemize}
723\end{frame}
724
725\end{document}
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