source: palm/trunk/TUTORIAL/SOURCE/topography.tex @ 1679

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\institute{Institute of Meteorology and Climatology, Leibniz UniversitÀt Hannover}
\selectlanguage{english}
\date{last update: \today}
\event{PALM Seminar}
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\title[PALM - Using Topography]{PALM - Using Topography}
\author{PALM group}

% Notes:
% jede subsection bekommt einen punkt im menu (vertikal ausgerichtet.
% jeder frame in einer subsection bekommt einen punkt (horizontal ausgerichtet)
\begin{document}
% Folie 1
\begin{frame}
\titlepage
\end{frame}


% Folie 2
\begin{frame}
   \frametitle{Contents – Using Topography (I)}
   \begin{itemize}
      \item{Purpose of topography in PALM} 
      \item{Realization}
      \begin{itemize}
         \item{Definition}
         \item{Physical concept}
         \item{Technical / numerical implementation}
         \item{Strengths and limitations}
      \end{itemize}
      \item{Control parameters}
      \begin{itemize}
         \item{Required / optional topography parameters}
         \item{Topography-related general control parameters}
         \begin{itemize}
            \item{Suitable driving methods, initial and boundary conditions}
            \item{Pressure solver}
         \end{itemize}
      \end{itemize}
      \item{Data output}
   \end{itemize}
\end{frame}

\section{Purpose}
\subsection{Purpose}

% Folie 3
\begin{frame}
   \frametitle{Purpose of Topography}
   \begin{itemize}
      \item{Optional feature to simulate flow around/above obstacles}
      \par\bigskip
      \item{Application fields}
      \begin{itemize}
         \item{Urban meteorology, wind engineering}
         \item{Mesoscale meteorology}
         \item{Oceanography}
         \item{...}
      \end{itemize} 
   \end{itemize}
\end{frame}

\section{Realization}
\subsection{Realization}

% Folie 4
\begin{frame}
   \frametitle{Definition}   
   \begin{itemize}
      \item{Topography in PALM covers solid, impermeable, fixed flow obstacles with a volume of at least one grid box.}
      \par\bigskip
      \item{Following qualifies as topography: \textcolor{green!50!black!100}{\checkmark}}      
      \begin{itemize}
         \footnotesize
         \item{Artificial obstacles (buildings)}
         \item{Natural obstacles (hills, mountains)}
      \end{itemize}
      \par\bigskip
      \item{The following does NOT qualify as topography: \textcolor{red}{$\times$}}
      \begin{itemize}
         \footnotesize
         \item{\begin{tabbing}Permeable obstacles (vegetation) $\}$  \= Parameterization options in PALM: \\
                                                                     \> canopy model, local roughness length  \end{tabbing} } 
         \item{Small obstacles (signposts)}
         \item{Moving obstacles (vehicles, wind turbine rotors)}                                                    
      \end{itemize}
   \end{itemize}
\end{frame}

% Folie 5
\begin{frame}
   \frametitle{Realization - Physical Concept}
   \scriptsize
   \begin{columns}[c]
   \column{0.8\textwidth}
      \begin{itemize}
         \item{Flow cannot enter topography and is forced around/above it.}
      \end{itemize}
   \column{0.2\textwidth}
   \end{columns}
   \begin{columns}[c]
   \column{0.4\textwidth}
      \begin{itemize}
         \item{Grid boxes are}
         \begin{itemize}
            \item{\begin{minipage}{0.4\textwidth} \scriptsize
                     \par\medskip
                     100\% \\free fluid, \\
                  \end{minipage}}
            \item{\begin{minipage}{0.4\textwidth} \scriptsize
                     100\% \\fluid adjacent to an obstacle, or
                  \end{minipage}}     
            \item{\begin{minipage}{0.4\textwidth} \scriptsize
                     \par\medskip
                     100\% obstacle. \\
                  \end{minipage}}             
         \end{itemize}
      \end{itemize}
   \column{0.6\textwidth}
      \vspace{-2.cm}\includegraphics[angle=90,width=.9\textwidth]{topography_figures/physical_concept.eps}
   \end{columns}
   \begin{columns}[c]
   \column{1.\textwidth}
      \begin{itemize}
         \item{No-slip boundary condition}
         \begin{itemize}
            \item{\scriptsize Wall-normal velocity component is zero at obstacle surface}
         \end{itemize}
         \par\bigskip
         \item{\begin{minipage}{0.8\textwidth}  \scriptsize
                  Local surface layer for the first grid box adjacent to each obstacle surface
               \end{minipage}
               \begin{minipage}{0.1\textwidth}
                  \includegraphics[width=0.35\textwidth]{topography_figures/physical_concept_small.eps}
               \end{minipage}}
         \par\smallskip
         \begin{itemize}
            \item{\scriptsize Neutral Monin-Obukhov similarity}
         \end{itemize}
      \end{itemize}
   \end{columns}
\end{frame}

% Folie 6
\begin{frame}
   \frametitle{Realization - \\ Numerical /Technical Implementation (I)}
   \small
   \begin{columns}[c]
   \column{0.65\textwidth}
      \begin{itemize}
         \item{Obstacles must be surface-mounted}
         \item{Overhanging structures \textbf{\textcolor{blue}{$\times$}}, holes \textbf{\textcolor{red}{$\times$}} etc. are not permitted.}
         \begin{itemize}
            \footnotesize
            \item{This simplification allows extra performance optimization by reducing the 3D obstacle structure to a "'2.5D"' structure.}
            \item{"'2.5D"' means that each surface grid cell is assigned only one building-height value (in m).}
            \item{This conforms to the "'2.5D"' format of Digital Elevation Models (DEM).}
         \end{itemize}
      \end{itemize}     
   \column{0.3\textwidth}
      \par\medskip
      \includegraphics[width=1.\textwidth]{topography_figures/technical_implementation.eps}
   \column{0.05\textwidth}
      \vspace*{2cm}\textcolor{red}{$\times$}
      \textcolor{green!50!black!100}{\checkmark}
   \end{columns}
\end{frame}

% Folie 7
\begin{frame}
   \frametitle{Realization - \\ Numerical /Technical Implementation (II)}
   \small
   \begin{columns}[c]
   \column{0.5\textwidth}
      \begin{itemize}
         \item{The location of the wall-normal velocity component defines the location of the impermeable obstacle surface}
         \item{Obstacle surfaces that do not match the grid are approximated by grid boxes like a step-function}
      \end{itemize}
      \par\bigskip
      \hspace{1cm}$\bullet$ scalars \\
      \hspace{1cm}\textcolor{red}{$\bullet$ u (staggered)} \\
      \hspace{.92cm}\textcolor{green!40!black!100}{\textbf{+} v (staggered)}
   \column{0.5\textwidth}
      \includegraphics[width=\textwidth]{topography_figures/technical_implementation_grid/technical_implementation_grid_5.png}
   \end{columns}
\end{frame}

% Folie 8
\begin{frame}
   \frametitle{Realization - \\ Numerical / Technical Implementation (III)}
   \footnotesize
   \textbf{Rastering GIS data: \dq from GIS data to ASCII raster data\dq}
   \begin{itemize}
      \item{In order to process topography from external data sources, the data must be made available 
            to PALM as a rastered ASCII file:}
      \begin{itemize}
         \item{see e.g. {\tt trunk/EXAMPLES/topo\_file/example\_topo\_file\_topo}.} 
      \end{itemize}
      \item{The layout of this topography file must conform to the computational domain size and to the grid size {\tt dx} and {\tt dy}.}
      \item{The rastered height data of this topo file are given in m above ground and do not need to match
            the vertical grid, since they will be interpolated, if required.}
      \par\bigskip
      \item{Software known to be able to perfom the rastering process of GIS data in vector and/or raster format to PALM raster format:}
      \begin{itemize}
         \item{ArcGIS (commercial)}
         \item{GRASS GIS (freeware)}
      \end{itemize}
   \end{itemize}
\end{frame}

% Folie 9
\begin{frame}
   \frametitle{Realization – \\ Numerical / Technical Implementation (IV)}  
   \small
   \textbf{Potential issue: Load imbalance}
   \begin{columns}[c]
   \column{0.55\textwidth}
      \begin{itemize}
         \item{Since prognostic equations are not calculated inside buildings, \\ \textbf{load imbalance} might occur, if topography is heterogeneously distributed among the subdomains.}
         \begin{itemize}
          \item{This means \dq fast\dq CPU(s) must wait for \dq slow\dq CPU(s), leading to inefficient parallelization.}
         \end{itemize}
      \end{itemize}
   \column{0.45\textwidth}
      \includegraphics[angle=90,width=\textwidth]{topography_figures/load_imbalance.eps}
   \end{columns}
\end{frame}

% Folie 10
\begin{frame}
   \frametitle{Summary: Strengths (+) and Limitations (–)}
   \small
   \begin{itemize}
      \item[+]{Horizontal and vertical surfaces can be exactly resolved (thanks to the finite difference Cartesian model architecture)}
      \item[+]{Optimization also for scalar computer architectures}
      \item[+]{Conforms with \dq 2.5D\dq format of Digital Elevation Models (DEM)} 
      \par\bigskip
      \item[$-$]{Obstacles must be surface-mounted}
      \item[$-$]{Overhanging structures, holes etc. are not permitted due to the \dq 2.5D\dq format}
      \item[$-$]{Grid boxes can only be 100\% fluid or 100\% obstacle \\ \par\smallskip
                \begin{footnotesize} Obstacle surfaces that do not match the grid are approximated by grid boxes like a step-function, which can modify the real obstacle size or the orientation of the obstacle faces\end{footnotesize}}
   \end{itemize}
\end{frame}

% Folie 11
\begin{frame}
   \frametitle{Take a Short Break... Urban Flow Visualization}
   \begin{columns}[c]
   \column{0.5\textwidth}
      \includegraphics<1->[width=.8\textwidth]{topography_figures/hannover_1.png}
      \par\smallskip
      \href{.html}{\includegraphics<2->[width=.8\textwidth]{topography_figures/hannover_2.png}}
   \column{0.5\textwidth}
      \par\smallskip
      \footnotesize
      \uncover<1->{Set-up: neutral boundary layer}
      \begin{itemize}
         \uncover<1->{\item{Particle = passive tracer}}
         \uncover<1->{\item{Colour $\sim$ particle height}}
         \uncover<1->{\item{Tail length ~ particle velocity}}         
      \end{itemize} 
      \begin{itemize}
         \uncover<2>{\item{Flow past office tower:}}
         \begin{itemize}
            \uncover<2>{\item{initially laminar: not yet an LES}}
            \uncover<2>{\item{intermittent: different episodes}}
         \end{itemize}
         \uncover<2>{\item{Broad street canyon flow:}}
         \begin{itemize}
            \uncover<2>{\item{channeling}}
            \uncover<2>{\item{low-level upstream flow}}
         \end{itemize}
      \end{itemize}
   \end{columns}
\end{frame}

\section{Control parameters}
\subsection{Control parameters}

% Folie 12
\begin{frame}
   \frametitle{Required Topography Control Parameters}
    \scriptsize
   \uncover<1->{{\tt topography =}}
   \begin{itemize}
      \uncover<1->{\item{{\tt 'flat'}                   \tabto{4cm} no topography (default)}}
      \uncover<1->{\item{{\tt 'single\_building'}       \tabto{4cm} \textcolor{red}{generic} single building}}
      \uncover<1->{\item{{\tt 'single\_street\_canyon'} \tabto{4cm} \textcolor{red}{generic} single quasi-2D street canyon}}
      \uncover<1->{\item{{\tt 'read\_from\_file'}       \tabto{4cm} \textcolor{blue}{rastered} ASCII file \\ \tabto{4cm}(e.g. {\tt trunk/EXAMPLES/topo\_file})}}
      \uncover<1->{\item{any other string               \tabto{4cm} processed by user subroutine user\_init\_grid}}
   \end{itemize}
   \uncover<2->{{\tt topography\_grid\_convention =}}
   \begin{itemize}
      \uncover<2->{\item{{\tt '\textcolor{red}{cell\_edge}'}    \tabto{4cm} default for \textcolor{red}{generic} topography: \textcolor{red}{$\leftrightarrow$}}}
      \uncover<3->{\item{{\tt '\textcolor{blue}{cell\_center}'} \tabto{4cm} default for \textcolor{blue}{rastered} topography: \textcolor{blue}{$\bigcirc$ $\leftrightarrow$}}}
   \end{itemize}
   \includegraphics<2|handout:0>[width=0.4\textwidth]{topography_figures/control_parameters_2.png}
   \includegraphics<3|handout:1>[width=0.4\textwidth]{topography_figures/control_parameters_4.png}
\end{frame}

% Folie 13
\begin{frame}
   \frametitle{Optional Topography Control Parameters (I)}
   \small
   \textbf{Generic topography}
   \begin{figure}
      \centering\includegraphics[width=.8\textwidth]{topography_figures/single_building_parameters.eps}
   \end{figure}
\end{frame}

% Folie 14
\begin{frame}
   \frametitle{Optional Topography Control Parameters (II)}
   \small
   \textbf{Generic topography}
   \begin{figure}
      \centering\includegraphics[width=.8\textwidth]{topography_figures/single_canyon_parameters.eps}
   \end{figure}
\end{frame}

% Folie 15
\begin{frame}
   \frametitle{Optional Topography Control Parameters (III)}
   \scriptsize   
   \textbf{Rastered topography}\\
   \begin{minipage}{0.8\textwidth}
      \begin{itemize}
         \scriptsize
         \item{{\tt topography} = 'read\_from\_file'} 
         \begin{itemize}
            \footnotesize
            \item{requires an external ASCII file, e.g. {\tt example\_topo:}}
         \end{itemize}
      \end{itemize}
   \end{minipage}
   \begin{minipage}{0.15\textwidth}
      \includegraphics[width=0.5\textwidth]{topography_figures/optional_control_parameters_1.png}
   \end{minipage}
   \begin{center}
      \includegraphics[width=0.75\textwidth]{topography_figures/optional_control_parameters_2.png}
   \end{center}
   \begin{itemize}
      \item[]{}
      \begin{itemize} 
         \scriptsize
         \item{ASCII file {\tt example\_topo} must be available as INPUT file, like {\tt example\_p3d} ({\tt JOBS/example/INPUT/})}     
         \item{layout must conform to domain size and grid size {\tt dx} and {\tt dy}}
         \item{height data in m above ground (INTEGER or REAL) do not need to match the vertical grid}
      \end{itemize}
   \end{itemize}
\end{frame}

% Folie 16
\begin{frame}
   \frametitle{Optional Topography Control Parameters (IV)}
   \small
   \textbf{Rastered topography}
   \begin{itemize}
      \item{{\tt topography} = 'read\_from\_file'}
      \par\smallskip
      \begin{itemize}
         \item{\textbf{mrun}-call: \\
               {\tt mrun ... -r 'd3\# ...'}}
         \par\medskip
         \item{{\tt .mrun.config:}}
      \end{itemize}
   \end{itemize}  
   \begin{center} \includegraphics[width=0.7\textwidth]{topography_figures/optional_control_parameters_3.png} \end{center}
\end{frame}

% Folie 17   
\begin{frame}
   \frametitle{General Control Parameters (I): Suitable Driving Methods}
   \scriptsize
   \begin{itemize}
      \item{\textbf{\dq Meteorological\dq set-up M: geostrophic wind / Coriolis force}}
      \begin{itemize}
         \scriptsize
         \item{Set {\tt omega $ \neq$ 0.0}}
         \item{Construct a non-zero profile of geostrophic wind $u_g$ and/or $v_g$ using {\tt ug\_surface}, {\tt ug\_vertical\_gradient}
               and {\tt ug\_vertical\_gradient\_level} and/or the respective parameter set for $v_g$}
      \end{itemize}
      \par\bigskip
      \item{\textbf{\dq Engineering\dq set-up E: direct external pressure gradient / no Coriolis force}}
      \begin{itemize}
         \scriptsize
         \item{Set {\tt omega = 0.0}}
         \item{Set-up E1: direct external pressure gradient that does not change with time 
                 (the bulk velocity fluctuates with time)}
         \begin{itemize}
            \scriptsize
            \item{Parameters: {\tt dp\_external}, {\tt dp\_smooth}, {\tt dp\_level\_b}, {\tt dpdxy}}
         \end{itemize}
         \item{Set-up E2: maintain a constant bulk velocity 
                 (the direct external pressure gradient fluctuates with time)}
         \begin{itemize}
             \scriptsize
             \item{Parameters: {\tt conserve\_volume\_flow}, {\tt conserve\_volume\_flow\_mode}, {\tt u\_bulk}, {\tt v\_bulk}}
         \end{itemize}
      \end{itemize}
      \par\bigskip
      \item{\textbf{\dq Thermal\dq set-up T: directly prescribe sensible heatflux}}
      \begin{itemize}
         \item[]{}
         \begin{itemize}
            \scriptsize
            \item{surface\_heatflux at ground level only} 
            \item{wall\_heatflux(0:4) at top/left/right/South/North obstacle face}
         \end{itemize}
      \end{itemize}
   \end{itemize}
\end{frame}

% Folie 18
\begin{frame}
   \frametitle{General Control Parameters (II): Initialization}
   \scriptsize
   \begin{itemize}
      \item{\textbf{\dq Meteorological\dq set-up M }\\
            Initialize a non-zero profile of geostrophic wind $u_g$ and/or $v_g$ using}
      \begin{itemize}
         \scriptsize
         \item{{\tt initializing\_actions =} \textbf{'set\_constant\_profiles' (e.g. for convective BL)}}
         \begin{itemize}
            \scriptsize
            \item{Parameters: {\tt ug\_surface $ \neq $ 0.0} and/or {\tt vg\_surface $\neq $ 0.0}}
         \end{itemize}
         \item{{\tt initializing\_actions =} \textbf{'set\_1d-model\_profiles' (e.g. for neutral BL)}}
         \begin{itemize}
            \scriptsize
            \item{1D model prerun parameters with suffix {\tt \_1d} (e.g. {\tt end\_time\_1d}, {\tt damp\_level\_1d)}}
         \end{itemize}
      \end{itemize}  
      \par\bigskip
      \item{\textbf{\dq Engineering\dq set-up E} \\
            Good initialization may require a priori knowlegde, e.g. from previous test runs. 
            Here, {\tt ug\_}... and {\tt vg\_}... don't refer to geostrophic wind but to the initial wind profile.} 
      \begin{itemize}
         \scriptsize
         \item{{\tt initializing\_actions} = \textbf{'set\_constant\_profiles'}}
         \begin{itemize}
            \scriptsize
            \item{Parameter set: {\tt ug\_surface}, {\tt ug\_vertical\_gradient}[{\tt \_level}] and/or the respective set for $v_g$}
         \end{itemize}
         \item{{\tt initializing\_actions} = \textbf{'set\_1d-model\_profiles'}}
         \item{{\tt initializing\_actions} = \textbf{'by\_user' – processed by user\_init\_3d\_model}}
      \end{itemize}
      \par\bigskip
      \item{\textbf{\dq Thermal\dq set-up T} \\
            Any of the above may apply}
   \end{itemize}
\end{frame}

% Folie 19
\begin{frame}
   \frametitle{General Control Parameters (III): Boundary Conditions}
   \footnotesize
   \begin{itemize}
      \item{Lateral boundary conditions}
      \begin{itemize}
         \item{Cyclic / non-cyclic: cf. lecture on \dq non-cyclic boundary conditions\dq}
      \end{itemize} 
      \item{Bottom boundary conditions}
      \begin{itemize}
         \item{Cf. lecture on \dq numerics and boundary conditions\dq}
      \end{itemize}
      \item{Top boundary conditions}
      \begin{itemize}
         \footnotesize
         \item{\textbf{Channel}: {\tt bc\_uv\_t =} \textbf{'dirichlet\_0' (no-slip)}}
         \item{\textbf{Open channel}: {\tt bc\_uv\_t =} \textbf{'neumann' (slip)}}
         \item{\textbf{\dq Constant flux\dq layer}: {\tt bc\_uv\_t =} \textbf{'neumann' (slip)} \\
                with set-up E1 where {\tt dp\_level\_b >> 0} and {\tt dp\_smooth = .T.}}
      \end{itemize}
   \end{itemize}
\end{frame}

% Folie 20
\begin{frame}
   \frametitle{General Control Parameters (IV): Pressure Solver} 
   {\tt psolver =}
   \par\medskip
   \begin{itemize}
      \item{'poisfft' (FFT scheme)} 
      \begin{itemize}
         \item{Good performance for urban PALM version}
         \item{Cannot be used with non-cyclic boundary conditions}
      \end{itemize}
      \par\bigskip
      \item{'multigrid' (Multigrid scheme)}
      \begin{itemize}
         \item{Performance for very large number of grid points may be better than FFT}
         \item{This is the only possible choice for non-cyclic boundary conditions}
      \end{itemize}
   \end{itemize}
\end{frame}

\section{Data output/ Scenarios}
\subsection{Data output/ Scenarios}

% Folie 21
\begin{frame}
   \frametitle{Data Analysis / Output – Some Considerations (I)}
   \scriptsize
   \begin{itemize}
      \item{How to get turbulence statistics?}
      \begin{itemize}
         \scriptsize
         \item{Phase averaging if a direction of homogeneity exists}
         \item{Temporal averaging}
         \item{Ensemble averaging}
      \end{itemize} 
      \item{Definition of turbulent fluctuations}\\
      \textbf{Spatial fluctuations:} deviation from representative instantaneous spatial average
      \begin{itemize}
         \scriptsize
         \item{PALM: many statistics calculated on-the-fly as time series, 1D vertical profiles}
         \item{Not suitable for topography unless a direction of homogeneity exists}
      \end{itemize}
      \textbf{Temporal fluctuations}: deviation from representative local temporal average
      \begin{itemize}
         \scriptsize
         \item{Suitable for all applications including topography}
         \item{Requires much hard disk space and post-processing CPU time}
         \item{PALM: not natively supported, but following procedure works:}
         \begin{itemize}
            \scriptsize
            \item{Collect time-series during the simulation (2D/3D data output or user-defined time series)}
            \item{Check for (quasi-)steady turbulent state and sufficient averaging time}
            \item{Calculate statistics by post-processing making use of the Reynolds decomposition: \\ \par\medskip
                  $\overline{w'\theta'} = \overline{w\theta} - \overline{w} \overline{\theta} $}
         \end{itemize}
      \end{itemize}    
   \end{itemize}
\end{frame}

% Folie 22
\begin{frame}
   \frametitle{Your Responsibility and Contribution}
   \footnotesize
   \par\medskip
   PALM's topography features have been frequently applied within the last years, but there may be still some parameter combinations which have not been used so far, and which may not work properly.
   \par\bigskip
%    For example, the combination of topography and non-cyclic lateral boundary conditions has not yet been tested 
%    because both features have originally been introduced separately for different research projects.
%    \par\bigskip 
   Therefore, we ask you for your responsibility and contribution:
   \begin{itemize}
      \item{Please always check your PALM setup carefully. PALM is not a black box.} 
      \item{For example, design a simple case and test your expectation.}
      \item{Please report potential bugs using our trouble ticket system.}
   \end{itemize}
\end{frame}

% Folie 23
\begin{frame}
   \frametitle{Some recent examples of topography/building applications with PALM}
   
   \scriptsize
   \textbf{Street canyon flows}
   \par\smallskip
   \tiny
   \textbf{Letzel, M.O., M. Krane and S. Raasch 2008}: High resolution urban large-eddy simulation studies from street canyon to neighbourhood scale, Atmos. Env.,
   \textbf{42}, 8770-8784, doi:10.1016/j.atmosenv.2008.08.001.\\
   \par\medskip

   \scriptsize
   \textbf{Turbulence generated by topography}
   \par\smallskip
   \tiny
   \textbf{Esau, I. and I. Repina, 2012}: Wind climate in Kongsfjorden, Svalbard, and attribution of leading wind driving mechanisms through turbulence-resolving simulations. Advances in Meteorology, 
   \textbf{Volume 2012}, Article ID 568454, 16 pages, doi:10.1155/2012/568454.\\
   \par\medskip
   
   \scriptsize
   \textbf{Airflow within or over building arrays}
   \par\smallskip
   \tiny
   \textbf{Abd Razak A., A. Hagishima, N. Ikegaya and J. Tanimoto, 2013}: Analysis of airflow over building arrays for assessment of urban wind environment. Building and Environment,
   \textbf{59}, 56-65, doi:10.1016/j.buildenv.2012.08.007. \\
   \par\smallskip
   \textbf{Kanda, M., A. Inagaki, T. Miyamoto, M. Gryschka and S. Raasch 2013}: A New Aerodynamic Parameterization for Real Urban Surfaces, Boundary-Layer Meteorol.,
    \textbf{148}, 357-377, doi:10.1007/s10546-013-9818-x. \\
   \par\medskip
       
   \scriptsize
   \textbf{Thermal effects of building walls}
   \par\smallskip
   \tiny
   \textbf{Park, S.B., J.J. Baik, S. Raasch and M.O. Letzel 2012}: A large-eddy simulation study of thermal effects on turbulent flow and dispersion in and above a street canyon., J. Appl. Meteor. Climatol.,
   \textbf{51}, 829-841, doi:10.1175/JAMC-D-11-0180.1.\\
   \par\medskip

   \scriptsize
   \textbf{PALM coupled to a building energy model}
   \par\smallskip
   \tiny
   \textbf{Yaghoobian, N., J. Kleissl and K. T. Paw U, 2014}: An Improved Three-Dimensional Simulation of the Diurnally Varying Street-Canyon Flow, Boundary-Layer Meteorol.,
   doi:http://dx.doi.org/10.1007/s10546-014-9940-4.\\
\end{frame}

% Folie 24
\begin{frame}
   \Large
   \begin{center} \textcolor{blue!90!black!100}{Topography - Scenario examples} \end{center}
\end{frame}

% Folie 25
\begin{frame}
   \frametitle{Set-up Scenario: Single Street Canyon (I)}
   \par\smallskip
   \textbf{Single quasi-2D street canyon in neutral open channel flow with constant bulk velocity}
   \par\smallskip
   \begin{itemize}
      \item{{\tt trunk/EXAMPLES/canyon/}}
      \begin{itemize}
         \item{Parameter file \hspace{2cm} {\tt example\_canyon\_p3d}}
         \item{Run-control file \hspace{1.78cm} {\tt example\_canyon\_rc}}
         \item{Some documentation \hspace{0.95cm} {\tt example\_canyon.odt}}
      \end{itemize}
   \end{itemize}
   \begin{center}
      \includegraphics[width=0.85\textwidth]{topography_figures/scenario_ssc_1.png}
   \end{center}
\end{frame}

% Folie 26
\begin{frame}
   \frametitle{Set-up Scenario: Single Street Canyon (II)}
   \textbf{The phase average makes use of homogeneity in y-direction:} \\
   {\tt section\_xz = -1}, {\tt data\_output = \textbf{'u\_xz\_av'}}, {\tt 'v\_xz\_av'}, {\tt 'w\_xz\_av'}
   \begin{center}
      \includegraphics[width=0.85\textwidth]{topography_figures/scenario_ssc_2.png}
   \end{center}
\end{frame}

% Folie 27
\begin{frame}
 \begin{tikzpicture}[remember picture, overlay]
      \node [shift={(6.5 cm, 5cm)}]  at (current page.south west)
         {%
         \begin{tikzpicture}[remember picture, overlay]
            \uncover<1>{\node at (2.75,-0.5) {\includegraphics[width=0.55\textwidth]{topography_figures/scenario_ssc_example_2.png}};}
            \uncover<1>{\node at (-3.25,-0.5) {\includegraphics[width=0.55\textwidth]{topography_figures/scenario_ssc_example_1.png}};}
         \end{tikzpicture}
         };
  \end{tikzpicture}
\end{frame}

% Folie 28
\begin{frame}
 \begin{tikzpicture}[remember picture, overlay]
      \node [shift={(6.5 cm, 5cm)}]  at (current page.south west)
         {%
         \begin{tikzpicture}[remember picture, overlay]
            \uncover<1>{\node at (2.75,-0.5) {\includegraphics[width=0.55\textwidth]{topography_figures/scenario_ssc_example_2.png}};}
            \uncover<1>{\node at (-3.25,-0.5) {\includegraphics[width=0.55\textwidth]{topography_figures/scenario_ssc_example_1.png}};}
            \uncover<1>{\node at (3.5,-0.2) {\includegraphics[width=0.38\textwidth]{topography_figures/scenario_ssc_example_5.png}};}
            \uncover<2>{\node at (-3.5,-0.2) {\includegraphics[width=0.48\textwidth]{topography_figures/scenario_ssc_example_4.png}};}
         \end{tikzpicture}
         };
  \end{tikzpicture}
\end{frame}

% Folie 29
\begin{frame}
   \frametitle{Set-up Scenario: Constant Flux Layer}
   \small
   \textbf{Single surface-mounted cube in neutral open channel flow with a constant flux layer}
   \begin{itemize}
      \item{{\tt trunk/EXAMPLES/constant\_flux\_layer/}}
      \begin{itemize}
         \footnotesize
         \item{Parameter file \hspace{2cm} {\tt example\_constant\_flux\_layer\_p3d}}
         \item{Run-control file \hspace{1.79cm} {\tt example\_constant\_flux\_layer\_rc}}
         \item{Some documentation \hspace{1.02cm} {\tt example\_constant\_flux\_layer.odt}}
      \end{itemize}
   \end{itemize}
   \begin{center}
      \includegraphics[width=0.85\textwidth]{topography_figures/scenario_cfl.png}
   \end{center}
\end{frame}

% Folie 30
\begin{frame}
 \begin{tikzpicture}[remember picture, overlay]
      \node [shift={(6.5 cm, 5cm)}]  at (current page.south west)
         {%
         \begin{tikzpicture}[remember picture, overlay]
            \uncover<1->{\node at (0,-0.5) {\includegraphics[width=0.7\textwidth]{topography_figures/scenario_cfl_example_1.png}};}
         \end{tikzpicture}
         };
  \end{tikzpicture}
\end{frame}

% Folie 31
\begin{frame}
 \begin{tikzpicture}[remember picture, overlay]
      \node [shift={(6.5 cm, 5cm)}]  at (current page.south west)
         {%
         \begin{tikzpicture}[remember picture, overlay]
            \uncover<1->{\node at (0,-0.5) {\includegraphics[width=0.7\textwidth]{topography_figures/scenario_cfl_example_1.png}};}
            \uncover<1->{\node at (3.5,-0.2) {\includegraphics[width=0.38\textwidth]{topography_figures/scenario_cfl_example_3.png}};}
            \uncover<2->{\node at (-3.5,-0.2) {\includegraphics[width=0.45\textwidth]{topography_figures/scenario_cfl_example_2.png}};}
         \end{tikzpicture}
         };
  \end{tikzpicture}
\end{frame}

% Folie 32
\begin{frame}
   \frametitle{Rules of Good Practise}
   \small
   \begin{itemize}
      \item{If you run PALM with topography, make sure that it is really LES...}
      \begin{itemize}
         \item{''Large eddies'' are ''small'' between obstacles}
         \begin{itemize}
            \item{use fine grid length to resolve turbulence there}
         \end{itemize}
         \item{Ratio of resolved to SGS fluxes}
      \end{itemize} 
      \item{Check for (quasi-)steady turbulent state and sufficient averaging time.}
      \begin{itemize}
         \item{Fluctuations of time series of E, E*, maximum velocity components etc.}
      \end{itemize}
      \item{Make sure that your PALM result is independent of numerical parameters such as domain size and grid size.}
      \begin{itemize}
         \item{Sensitivity studies}
      \end{itemize}
      \item{If you intend to do a comparison with some kind of reference data, it is essential to configure the set-up of PALM 
           in the same way as the reference experiment.}
      \begin{itemize}
         \item{For example, if you compare PALM with wind tunnel results, you have to follow the wind tunnel set-up for setting up PALM.}
      \end{itemize}
   \end{itemize}
\end{frame}

\end{document}