source: palm/trunk/TUTORIAL/SOURCE/topography.tex @ 1434

Last change on this file since 1434 was 1226, checked in by fuhrmann, 11 years ago

several updates in the tutorial

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1%$Id: topography.tex 1226 2013-09-18 13:19:19Z keck $
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|handout:0>[width=\textwidth]{topography_figures/technical_implementation_grid/technical_implementation_grid_1.png}
219      \includegraphics<2|handout:0>[width=\textwidth]{topography_figures/technical_implementation_grid/technical_implementation_grid_2.png}
220      \includegraphics<3|handout:0>[width=\textwidth]{topography_figures/technical_implementation_grid/technical_implementation_grid_3.png}
221      \includegraphics<4|handout:0>[width=\textwidth]{topography_figures/technical_implementation_grid/technical_implementation_grid_4.png}
222      \includegraphics<5|handout:1>[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 will be interpolated, if required.}
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 (only if Piacsek-Williams advection scheme is used)}
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         \item{The default Wicker-Skamarock scheme does not show any instabilities}
267      \end{itemize}
268   \end{itemize}
269\end{frame}
270
271% Folie 10
272\begin{frame}
273   \frametitle{Summary: Strengths (+) and Limitations (–)}
274   \small
275   \begin{itemize}
276      \item[+]{Horizontal and vertical surfaces can be exactly resolved (thanks to the finite difference Cartesian model architecture)}
277      \item[+]{Optimization also for scalar computer architectures}
278      \item[+]{Conforms with \dq 2.5D\dq format of Digital Elevation Models (DEM)} 
279      \par\bigskip
280      \item[-]{Obstacles must be surface-mounted}
281      \item[-]{Grid boxes can only be 100\% fluid or 100\% obstacle \\ \par\smallskip
282              \begin{footnotesize} Obstacle surfaces that do not match the grid are approximated by grid boxes like a step-function, which
283              modifies the real obstacle size \end{footnotesize}}
284      \item[-]{Overhanging structures, holes etc. are not permitted due to the \dq 2.5D\dq format}
285   \end{itemize}
286\end{frame}
287
288% Folie 11
289\begin{frame}
290   \frametitle{Take a Short Break... Urban Flow Visualization}
291   \begin{columns}[c]
292   \column{0.42\textwidth}
293      \includegraphics<1>[width=\textwidth]{topography_figures/hannover_1.png}
294      \href{.html}{\includegraphics<2>[width=\textwidth]{topography_figures/hannover_2.png}}
295   \column{0.58\textwidth}
296      Set-up: neutral boundary layer
297      \begin{itemize}
298         \item{Particle = passive tracer}
299         \item{Colour $\sim$ particle height}
300         \item{Tail length ~ particle velocity}         
301      \end{itemize}     
302      \par\bigskip
303      \begin{itemize}
304         \item{Flow past office tower:}
305         \begin{itemize}
306            \item{initially laminar: not yet an LES}
307            \item{intermittent: different episodes}
308         \end{itemize}
309         \item{Broad street canyon flow:}
310         \begin{itemize}
311            \item{channeling}
312            \item{low-level upstream flow}
313         \end{itemize}
314      \end{itemize}
315   \end{columns}
316\end{frame}
317
318% Folie 12
319\begin{frame}
320   \frametitle{Required Topography Control Parameters}
321    \footnotesize
322   {\tt topography =} 
323   \begin{itemize}
324      \item{{\tt 'flat'} \hspace{3cm} no topography (default)}
325      \item{{\tt 'single\_building'} \hspace{1.2cm} \textcolor{red}{generic} single building} 
326      \item{{\tt 'single\_street\_canyon'} \hspace{0.4cm} \textcolor{red}{generic} single quasi-2D street canyon}
327      \item{{\tt 'read\_from\_file'} \hspace{1.4cm} \textcolor{blue}{rastered} ASCII file, e.g. {\tt example\_topo}}
328      \item{any other string \hspace{1.8cm} processed by user subroutine user\_init\_grid}
329   \end{itemize}
330   {\tt topography\_grid\_convention =}
331   \begin{itemize}
332      \item{{\tt '\textcolor{red}{cell\_edge}'} \hspace{2.2cm} default for \textcolor{red}{generic} topography: \textcolor{red}{$\leftrightarrow$}}
333      \item{{\tt '\textcolor{blue}{cell\_center}'} \hspace{1.9cm} default for \textcolor{blue}{rastered} topography: \textcolor{blue}{$\bigcirc$ $\leftrightarrow$}} 
334   \end{itemize}
335   \includegraphics<1|handout:0>[width=0.5\textwidth]{topography_figures/control_parameters_1.png}
336   \includegraphics<2|handout:0>[width=0.5\textwidth]{topography_figures/control_parameters_2.png}
337   \includegraphics<3|handout:0>[width=0.5\textwidth]{topography_figures/control_parameters_3.png}
338   \includegraphics<4|handout:1>[width=0.5\textwidth]{topography_figures/control_parameters_4.png}
339\end{frame}
340
341% Folie 13
342\begin{frame}
343   \frametitle{Optional Topography Control Parameters (I)}
344   \small
345   \textbf{Generic topography}   
346   \scriptsize
347   \begin{itemize}
348      \item{topography = {\tt 'single\_building'}} 
349      \begin{itemize}
350         \scriptsize
351         \item{building\_height = 50.0 \hspace{0.67cm} height of the building}
352         \item{building\_length\_x = 50.0 \hspace{0.43cm} length of the building in x-direction}
353         \item{building\_length\_y = 50.0 \hspace{0.43cm} length of the building in y-direction}
354         \item{building\_wall\_left \hspace{1.4cm} (default is building centered in x-direction)}
355         \item{building\_wall\_south \hspace{1.13cm} (default is building centered in y-direction)}
356      \end{itemize}
357      \item{topography = {\tt 'single\_street\_canyon'}}
358      \begin{itemize}
359         \scriptsize
360         \item{canyon\_height = 50.0 \hspace{0.45cm} height of the canyon \\
361               and}
362         \item{canyon\_width\_x = 50.0 \hspace{0.3cm} implies canyon axis orientation in y-direction}
363         \item{canyon\_wall\_left \hspace{1.17cm} (default is canyon centered in x-direction) \\
364               or}
365         \item{canyon\_width\_y = 50.0 \hspace{0.3cm} implies canyon axis orientation in x-direction}
366         \item{canyon\_wall\_south \hspace{0.9cm} (default is canyon centered in y-direction)}
367      \end{itemize}
368   \end{itemize}
369\end{frame}
370
371% Folie 14
372\begin{frame}
373   \frametitle{Optional Topography Control Parameters (II)}
374   \scriptsize   
375   \textbf{Rastered topography}\\
376   \begin{minipage}{0.7\textwidth}
377      \begin{itemize}
378         \scriptsize
379         \item{{\tt topography} = 'read\_from\_file'} 
380         \begin{itemize}
381            \footnotesize
382            \item{requires an external ASCII file, e.g. {\tt example\_topo:}}
383         \end{itemize}
384      \end{itemize}
385   \end{minipage}
386   \begin{minipage}{0.2\textwidth}
387      \includegraphics[width=0.5\textwidth]{topography_figures/optional_control_parameters_1.png}
388   \end{minipage}
389   \begin{center}
390      \includegraphics[width=0.85\textwidth]{topography_figures/optional_control_parameters_2.png}
391   \end{center}
392   \begin{itemize}
393      \item[]{}
394      \begin{itemize} 
395         \scriptsize         
396         \item{layout must conform to domain size and grid size dx and dy.}
397         \item{height data}
398         \begin{itemize}
399            \scriptsize
400            \item{in m above ground (INTEGER or REAL)}
401            \item{do not need to match the vertical grid}
402         \end{itemize}
403      \end{itemize}
404   \end{itemize}
405\end{frame}
406
407% Folie 15
408\begin{frame}
409   \frametitle{Optional Topography Control Parameters (III)}
410   \small
411   \textbf{Rastered topography}
412   \begin{itemize}
413      \item{{\tt topography} = 'read\_from\_file'}
414      \par\smallskip
415      \begin{itemize}
416         \item{\textbf{mrun}-call: \\
417               {\tt mrun ... -r 'd3\# ...'}}
418         \par\medskip
419         \item{{\tt .mrun.config:}}
420      \end{itemize}
421   \end{itemize} 
422   \begin{center} \includegraphics[width=0.7\textwidth]{topography_figures/optional_control_parameters_3.png} \end{center}
423\end{frame}
424
425% Folie 16   
426\begin{frame}
427   \frametitle{General Control Parameters (I): Suitable Driving Methods}
428   \scriptsize
429   \begin{itemize}
430      \item{\textbf{\dq Meteorological\dq set-up M: geostrophic wind / Coriolis force}}
431      \begin{itemize}
432         \scriptsize
433         \item{Set {\tt omega $ \neq$ 0.0}}
434         \item{Construct a non-zero profile of geostrophic wind $u_g$ and/or $v_g$ using {\tt ug\_surface}, {\tt ug\_vertical\_gradient}
435               and {\tt ug\_vertical\_gradient\_level} and/or the respective parameter set for $v_g$}
436      \end{itemize}
437      \par\bigskip
438      \item{\textbf{\dq Engineering\dq set-up E: direct external pressure gradient / no Coriolis force}}
439      \begin{itemize}
440         \scriptsize
441         \item{Set {\tt omega = 0.0}}
442         \item{Set-up E1: direct external pressure gradient that does not change with time
443                 (the bulk velocity fluctuates with time)}
444         \begin{itemize}
445            \scriptsize
446            \item{Parameters: {\tt dp\_external}, {\tt dp\_smooth}, {\tt dp\_level\_b}, {\tt dpdxy}}
447         \end{itemize}
448         \item{Set-up E2: maintain a constant bulk velocity
449                 (the direct external pressure gradient fluctuates with time)}
450         \begin{itemize}
451             \scriptsize
452             \item{Parameters: {\tt conserve\_volume\_flow}, {\tt conserve\_volume\_flow\_mode}, {\tt u\_bulk}, {\tt v\_bulk}}
453         \end{itemize}
454      \end{itemize}
455      \par\bigskip
456      \item{\textbf{\dq Thermal\dq set-up T: directly prescribe sensible heatflux}}
457      \begin{itemize}
458         \item[]{}
459         \begin{itemize}
460            \scriptsize
461            \item{surface\_heatflux at ground level only} 
462            \item{wall\_heatflux(0:4) at top/left/right/South/North obstacle face}
463         \end{itemize}
464      \end{itemize}
465   \end{itemize}
466\end{frame}
467
468% Folie 17
469\begin{frame}
470   \frametitle{General Control Parameters (II): Initialization}
471   \scriptsize
472   \begin{itemize}
473      \item{\textbf{\dq Meteorological\dq set-up M }\\
474            Initialize a non-zero profile of geostrophic wind $u_g$ and/or $v_g$ using}
475      \begin{itemize}
476         \scriptsize
477         \item{{\tt initializing\_actions =} \textbf{'set\_constant\_profiles' (e.g. for convective BL)}}
478         \begin{itemize}
479            \scriptsize
480            \item{Parameters: {\tt ug\_surface $ \neq $ 0.0} and/or {\tt vg\_surface $\neq $ 0.0}}
481         \end{itemize}
482         \item{{\tt initializing\_actions =} \textbf{'set\_1d-model\_profiles' (e.g. for neutral BL)}}
483         \begin{itemize}
484            \scriptsize
485            \item{1D model prerun parameters with suffix {\tt \_1d} (e.g. {\tt end\_time\_1d}, {\tt damp\_level\_1d)}}
486         \end{itemize}
487      \end{itemize} 
488      \par\bigskip
489      \item{\textbf{\dq Engineering\dq set-up E} \\
490            Good initialization may require a priori knowlegde, e.g. from previous test runs.
491            Here, {\tt ug\_}... and {\tt vg\_}... don't refer to geostrophic wind but to the initial wind profile.} 
492      \begin{itemize}
493         \scriptsize
494         \item{{\tt initializing\_actions} = \textbf{'set\_constant\_profiles'}}
495         \begin{itemize}
496            \scriptsize
497            \item{Parameter set: {\tt ug\_surface}, {\tt ug\_vertical\_gradient}[{\tt \_level}] and/or the respective set for $v_g$}
498         \end{itemize}
499         \item{{\tt initializing\_actions} = \textbf{'set\_1d-model\_profiles'}}
500         \item{{\tt initializing\_actions} = \textbf{'by\_user' – processed by user\_init\_3d\_model}}
501      \end{itemize}
502      \par\bigskip
503      \item{\textbf{\dq Thermal\dq set-up T} \\
504            Any of the above may apply}
505   \end{itemize}
506\end{frame}
507
508% Folie 18
509\begin{frame}
510   \frametitle{General Control Parameters (III): Boundary Conditions}
511   \footnotesize
512   \begin{itemize}
513      \item{Lateral boundary conditions}
514      \begin{itemize}
515         \item{Cyclic / non-cyclic: cf. lecture on \dq non-cyclic boundary conditions\dq}
516      \end{itemize} 
517      \item{Bottom boundary conditions}
518      \begin{itemize}
519         \item{Cf. lecture on \dq numerics and boundary conditions\dq}
520      \end{itemize}
521      \item{Top boundary conditions}
522      \begin{itemize}
523         \footnotesize
524         \item{\textbf{Channel}: {\tt bc\_uv\_t =} \textbf{'dirichlet\_0' (no-slip)}}
525         \item{\textbf{Open channel}: {\tt bc\_uv\_t =} \textbf{'neumann' (slip)}}
526         \item{\textbf{\dq Constant flux\dq layer} (not yet published): {\tt bc\_uv\_t =} \textbf{'neumann' (slip)} \\
527                with set-up E1 where {\tt dp\_level\_b >> 0} and {\tt dp\_smooth = .T.}}
528      \end{itemize}
529   \end{itemize}
530\end{frame}
531
532% Folie 19
533\begin{frame}
534   \frametitle{General Control Parameters (IV): Pressure Solver} 
535   {\tt psolver =}
536   \par\medskip
537   \begin{itemize}
538      \item{'poisfft' (FFT scheme)} 
539      \begin{itemize}
540         \item{Good performance for urban PALM version}
541         \item{Cannot be used with non-cyclic boundary conditions}
542      \end{itemize}
543      \par\bigskip
544      \item{'multigrid' (Multigrid scheme)}
545      \begin{itemize}
546         \item{Performance for very large number of grid points may be better than FFT}
547         \item{This is the only possible choice for non-cyclic boundary conditions}
548      \end{itemize}
549   \end{itemize}
550\end{frame}
551
552% Folie 20
553\begin{frame}
554   \frametitle{Data Analysis / Output – Some Considerations (I)}
555   \scriptsize
556   \begin{itemize}
557      \item{How to get turbulence statistics?}
558      \begin{itemize}
559         \scriptsize
560         \item{Phase averaging if a direction of homogeneity exists}
561         \item{Temporal averaging}
562         \item{Ensemble averaging}
563      \end{itemize} 
564      \item{Definition of turbulent fluctuations}\\
565      \textbf{Spatial fluctuations:} deviation from representative instantaneous spatial average
566      \begin{itemize}
567         \scriptsize
568         \item{PALM: many statistics calculated on-the-fly as time series, 1D vertical profiles}
569         \item{Not suitable for topography unless a direction of homogeneity exists}
570      \end{itemize}
571      \textbf{Temporal fluctuations}: deviation from representative local temporal average
572      \begin{itemize}
573         \scriptsize
574         \item{Suitable for all applications including topography}
575         \item{Requires much hard disk space and post-processing CPU time}
576         \item{PALM: not natively supported, but following procedure works:}
577         \begin{itemize}
578            \scriptsize
579            \item{Collect time-series during the simulation (2D/3D data output or user-defined time series)}
580            \item{Check for (quasi-)steady turbulent state and sufficient averaging time}
581            \item{Calculate statistics by post-processing making use of the Reynolds decomposition: \\ \par\medskip
582                  $\overline{w'\theta'} = \overline{w\theta} - \overline{w} \overline{\theta} $}
583         \end{itemize}
584      \end{itemize}   
585   \end{itemize}
586\end{frame}
587
588% Folie 21
589\begin{frame}
590   \frametitle{Your Responsibility and Contribution}
591   \footnotesize
592   \par\medskip
593   In most cases, a new parameter is added to PALM for one specific purpose.
594   \par\bigskip
595   Beyond this one purpose, each new parameter normally gives many other new feature/parameter combinations in PALM.
596   We are unable to check all these combinations by ourselves and rely on your help!
597   \par\bigskip
598%    For example, the combination of topography and non-cyclic lateral boundary conditions has not yet been tested
599%    because both features have originally been introduced separately for different research projects.
600%    \par\bigskip
601   Therefore, we ask you for your responsibility and contribution:
602   \begin{itemize}
603      \item{Please always check your PALM setup carefully. PALM is not a black box.} 
604      \item{For example, design a simple case and test your expectation.}
605      \item{Please report potential bugs – thank you!}
606      \begin{itemize}
607         \item{PALM developer team}
608         \item{PALM user community (via trac-system)}
609      \end{itemize}
610   \end{itemize}
611\end{frame}
612
613% Folie 22
614\begin{frame}
615   \Large
616   \begin{center} \textcolor{blue!90!black!100}{Topography - Scenario examples} \end{center}
617\end{frame}
618
619% Folie 23
620\begin{frame}
621   \frametitle{Set-up Scenario: Single Street Canyon (I)}
622   \par\smallskip
623   \textbf{Single quasi-2D street canyon in neutral open channel flow with constant bulk velocity}
624   \par\smallskip
625   \begin{itemize}
626      \item{{\tt trunk/EXAMPLES/canyon/}}
627      \begin{itemize}
628         \item{Parameter file \hspace{2cm} {\tt example\_canyon\_p3d}}
629         \item{Run-control file \hspace{1.78cm} {\tt example\_canyon\_rc}}
630         \item{Some documentation \hspace{0.95cm} {\tt example\_canyon.odt}}
631      \end{itemize}
632   \end{itemize}
633   \begin{center}
634      \includegraphics[width=0.85\textwidth]{topography_figures/scenario_ssc_1.png}
635   \end{center}
636\end{frame}
637
638% Folie 24
639\begin{frame}
640   \frametitle{Set-up Scenario: Single Street Canyon (II)}
641   \textbf{The phase average makes use of homogeneity in y-direction:} \\
642   {\tt section\_xz = -1}, {\tt data\_output = \textbf{'u\_xz\_av'}}, {\tt 'v\_xz\_av'}, {\tt 'w\_xz\_av'}
643   \begin{center}
644      \includegraphics[width=0.85\textwidth]{topography_figures/scenario_ssc_2.png}
645   \end{center}
646\end{frame}
647
648% Folie 25
649\begin{frame}
650 \begin{tikzpicture}[remember picture, overlay]
651      \node [shift={(6.5 cm, 5cm)}]  at (current page.south west)
652         {%
653         \begin{tikzpicture}[remember picture, overlay]
654            \uncover<1>{\node at (0,-0.5) {\includegraphics[width=0.7\textwidth]{topography_figures/scenario_ssc_example_1.png}};}
655            \uncover<2>{\node at (0,-0.5) {\includegraphics[width=0.7\textwidth]{topography_figures/scenario_ssc_example_2.png}};}
656            \uncover<3->{\node at (0,-0.5) {\includegraphics[width=0.7\textwidth]{topography_figures/scenario_ssc_example_3.png}};}
657            \uncover<4->{\node at (-3.5,-0.2) {\includegraphics[width=0.48\textwidth]{topography_figures/scenario_ssc_example_4.png}};}
658            \uncover<5->{\node at (3.5,-0.2) {\includegraphics[width=0.38\textwidth]{topography_figures/scenario_ssc_example_5.png}};}
659         \end{tikzpicture}
660         };
661  \end{tikzpicture}
662\end{frame}
663
664% Folie 26
665\begin{frame}
666   \frametitle{Set-up Scenario: Constant Flux Layer}
667   \small
668   \textbf{Single surface-mounted cube in neutral open channel flow with a constant flux layer}
669   \begin{itemize}
670      \item{{\tt trunk/EXAMPLES/constant\_flux\_layer/}}
671      \begin{itemize}
672         \footnotesize
673         \item{Parameter file \hspace{2cm} {\tt example\_constant\_flux\_layer\_p3d}}
674         \item{Run-control file \hspace{1.79cm} {\tt example\_constant\_flux\_layer\_rc}}
675         \item{Some documentation \hspace{1.02cm} {\tt example\_constant\_flux\_layer.odt}}
676      \end{itemize}
677   \end{itemize}
678   \begin{center}
679      \includegraphics[width=0.85\textwidth]{topography_figures/scenario_cfl.png}
680   \end{center}
681\end{frame}
682
683% Folie 27
684\begin{frame}
685 \begin{tikzpicture}[remember picture, overlay]
686      \node [shift={(6.5 cm, 5cm)}]  at (current page.south west)
687         {%
688         \begin{tikzpicture}[remember picture, overlay]
689            \uncover<1->{\node at (0,-0.5) {\includegraphics[width=0.7\textwidth]{topography_figures/scenario_cfl_example_1.png}};}
690            \uncover<2->{\node at (-3.5,-0.2) {\includegraphics[width=0.45\textwidth]{topography_figures/scenario_cfl_example_2.png}};}
691            \uncover<3->{\node at (3.5,-0.2) {\includegraphics[width=0.38\textwidth]{topography_figures/scenario_cfl_example_3.png}};}
692         \end{tikzpicture}
693         };
694  \end{tikzpicture}
695\end{frame}
696
697% Folie 28
698\begin{frame}
699   \frametitle{Rules of Good Practise}
700   \small
701   \begin{itemize}
702      \item{If you run PALM with topography, make sure that it is really LES...}
703      \begin{itemize}
704         \item{''Large eddies'' are ''small'' between obstacles}
705         \begin{itemize}
706            \item{use fine grid length to resolve turbulence there}
707         \end{itemize}
708         \item{Ratio of resolved to SGS fluxes}
709      \end{itemize} 
710      \item{Check for (quasi-)steady turbulent state and sufficient averaging time.}
711      \begin{itemize}
712         \item{Fluctuations of time series of E, E*, maximum velocity components etc.}
713      \end{itemize}
714      \item{Make sure that your PALM result is independent of numerical parameters such as domain size and grid size.}
715      \begin{itemize}
716         \item{Sensitivity studies}
717      \end{itemize}
718      \item{If you intend to do a comparison with some kind of reference data, it is essential to configure the set-up of PALM
719           in the same way as the reference experiment.}
720      \begin{itemize}
721         \item{For example, if you compare PALM with wind tunnel results, you have to follow the wind tunnel set-up for setting up PALM.}
722      \end{itemize}
723   \end{itemize}
724\end{frame}
725
726\end{document}
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