% $Id: exercise_neutral.tex 1228 2013-09-19 15:14:26Z witha $ \input{header_tmp.tex} %\input{../header_lectures.tex} \usepackage[utf8]{inputenc} \usepackage{ngerman} \usepackage{pgf} \usetheme{Dresden} \usepackage{subfigure} \usepackage{units} \usepackage{tabto} \usepackage{multimedia} \usepackage{hyperref} \newcommand{\event}[1]{\newcommand{\eventname}{#1}} \usepackage{xmpmulti} \usepackage{tikz} \usetikzlibrary{shapes,arrows,positioning} \usetikzlibrary{decorations.markings} %neues paket \usetikzlibrary{decorations.pathreplacing} %neues paket \def\Tiny{\fontsize{4pt}{4pt}\selectfont} \usepackage{amsmath} \usepackage{amssymb} \usepackage{multicol} \usepackage{pdfcomment} \usepackage{graphicx} \usepackage{listings} \lstset{showspaces=false,language=fortran,basicstyle= \ttfamily,showstringspaces=false,captionpos=b} \institute{Institut für Meteorologie und Klimatologie, Leibniz Universität Hannover} \date{last update: \today} \event{PALM Seminar} \setbeamertemplate{navigation symbols}{} \setbeamertemplate{footline} { \begin{beamercolorbox}[rightskip=-0.1cm]& {\includegraphics[height=0.65cm]{imuk_logo.pdf}\hfill \includegraphics[height=0.65cm]{luh_logo.pdf}} \end{beamercolorbox} \begin{beamercolorbox}[ht=2.5ex,dp=1.125ex, leftskip=.3cm,rightskip=0.3cm plus1fil]{title in head/foot} {\leavevmode{\usebeamerfont{author in head/foot}\insertshortauthor} \hfill \eventname \hfill \insertframenumber \; / \inserttotalframenumber} \end{beamercolorbox} \begin{beamercolorbox}[colsep=1.5pt]{lower separation line foot} \end{beamercolorbox} } %\logo{\includegraphics[width=0.3\textwidth]{luhimuk_logo.pdf}} \title[Exercise 2: Neutrally Stratified Boundary Layer]{Exercise 2: Neutrally Stratified Boundary Layer} \author{Siegfried Raasch} \setbeamersize{text margin left=.2cm,text margin right=.2cm} \begin{document} \footnotesize % Folie 1 \begin{frame} \titlepage \end{frame} \section{Exercise} \subsection{Exercise} % Folie 2 \begin{frame} \frametitle{Exercise 2: Neutrally Stratified Atmospheric Boundary Layer} \begin{itemize} \item A neutrally stratified atmospheric boundary layer shall be simulated. \item<2-> The flow shall be driven by a constant large-scale pressure gradient, i.e. a geostrophic wind. \item<3-> At the end of the simulation, turbulence as well as the mean flow should be in a stationary state. \end{itemize} \onslide<4->\textbf{Simulation features:} \begin{itemize} \item<4-> geostrophic wind: \tabto{3cm} $u_\mathrm{g} = \unit[5]{m\ s^{-1}}, v_\mathrm{g} = \unit[0]{m\ s^{-1}}$ \item<5-> initial velocity: \tabto{3cm} try constant velocity ($u = u_\mathrm{g}, v = v_\mathrm{g}$, everywhere)\\ \tabto{3cm} or a mean vertical profile created by the 1D-model \item<6-> roughness length: \tabto{3cm} $z_0 = \unit[0.1]{m}$ \end{itemize} \onslide<7->Please choose domain size, grid size and time to be simulated appropriately. \end{frame} % Folie 3 \begin{frame} \frametitle{Questions to be Answered:} \begin{itemize} \item<1-> How long do you have to simulate until turbulence / mean flow become stationary? \vspace{1em} \item<2-> How do the horizontally and temporally averaged vertical velocity and momentum flux profiles look like? \vspace{1em} \item<3-> Is it really a large-eddy simulation, i.e. are the subgrid-scale fluxes much smaller than the resolved-scale fluxes? \vspace{1em} \item<4-> How do the turbulence spectra of $u$, $v$, $w$ along $x$ and along $y$ look like?\\ Can you identify the inertial subrange? \end{itemize} \end{frame} % Folie 4 \begin{frame} \frametitle{Hints (I)} \begin{itemize} \item<1-> Please remember hints given for the previous exercise! \item<2-> \textbf{Initial profiles:} \begin{itemize} \tiny \item<3-> The 1D-model (\texttt{\textcolor{blue}{initializing\_actions} = 'set\_1d-model\_profiles'}) is mainly controlled by parameters \texttt{\textcolor{blue}{end\_time\_1d}} and \texttt{\textcolor{blue}{damp\_level\_1d}}. Please keep in mind that the profiles from the 1D-model should also be in a stationary state. \vspace{0.5em} \item<3-> Output of vertical profile data generated by the 1D-model is controlled by parameter \texttt{\textcolor{blue}{dt\_pr\_1d}}. It is in ASCII-format and it is written into a separate file. You can include the profiles of the 1D-model, which are used to initialize the 3D-model, in the standard profile data output of the 3D-model (which is controlled by parameter \texttt{\textcolor{blue}{data\_output\_pr}}) by adding a \texttt{'\#'} sign to the respective output quantity, e.g. \texttt{\textcolor{blue}{data\_output\_pr} = '\#u'}. \vspace{0.5em} \item<3-> For the 1D-model, please set \texttt{\textcolor{blue}{mixing\_length\_1d} = 'blackadar'} and \texttt{\textcolor{blue}{dissipation\_1d} = 'detering'} in order to get a correct mean boundary layer wind profile. The default settings of these parameters would switch the turbulence parameterization of the 1D-model to the SGS-parameterization of the 3D-LES-model, which represents only the SGS-parts of turbulence. However, for this exercise the 1D-model has to parameterize all scales of turbulence (i.e. it should be used as a RANS-model). \end{itemize} \item<4-> \textbf{Stationary state:} \begin{itemize} \tiny \item<4-> You probably will find it difficult to get the mean flow to a stationary state (for the 1D-model as well as for the 3D-model. Can you identify the mechanism responsible for this? Try parameters \texttt{\textcolor{blue}{damp\_level\_1d}} (for the 1D-model) and \texttt{\textcolor{blue}{rayleigh\_damping\_factor}} (for the 3D-model; this is a \texttt{inipar}-parameter!) to overcome this problem. \vspace{0.5em} \item<5-> You can switch on a Galilei-transformation in order to save CPU-time (see parameter \texttt{\textcolor{blue}{galilei\_transformation}}). \end{itemize} \end{itemize} \end{frame} % Folie 5 \begin{frame} \frametitle{Hints (II)} \begin{itemize} \item<1-> \textbf{Spectra:} \begin{itemize} \scriptsize \item<2-> Output of spectra requires to switch on the spectra-package using \textbf{mrun}-option \texttt{-p}:\\ \texttt{mrun ... -p spectra -r \dq d3\# sp\# ...\dq} \vspace{0.5em} \item<3-> Spectra output is controlled by parameters \texttt{\textcolor{blue}{data\_output\_sp}}, \texttt{\textcolor{blue}{dt\_dosp}}, etc. These package-parameters have to be given in a separate NAMELIST-block which has to follow the \texttt{d3par}-block:\\ \texttt{\&d3par end\_time = ... /}\\ \texttt{\&spectra\_par data\_output\_sp = ... /}\\ \end{itemize} \end{itemize} \end{frame} % Folie 6 \section{Results} \subsection{Results} % Folie 7 \begin{frame} \frametitle{Time series of TKE} \begin{center} \includegraphics[width=1.0\textwidth]{exercise_neutral_figures/ts.eps} \end{center} \end{frame} % Folie 8 \begin{frame} \frametitle{Vertical profiles of $\overline{w'u'}$, $\overline{w'v'}$} \begin{center} \includegraphics[width=0.50\textwidth]{exercise_neutral_figures/pr_wu.eps} \includegraphics[width=0.50\textwidth]{exercise_neutral_figures/pr_wv.eps}\\ \end{center} \end{frame} % Folie 9 \begin{frame} \frametitle{Vertical profiles of $\overline{w'u'}$, $\overline{w'v'}$} \begin{center} \includegraphics[width=0.36\textwidth]{exercise_neutral_figures/pr_wu_sgs.eps} \includegraphics[width=0.36\textwidth]{exercise_neutral_figures/pr_wv_sgs.eps}\\ \vspace{-0.3em} \includegraphics[width=0.36\textwidth]{exercise_neutral_figures/pr_wu_resolved.eps} \includegraphics[width=0.36\textwidth]{exercise_neutral_figures/pr_wv_resolved.eps}\\ \end{center} \end{frame} % Folie 10 \begin{frame} \frametitle{Spectra of $u$, $v$ and $w$} \hspace{-1em} \includegraphics[width=0.36\textwidth]{exercise_neutral_figures/sp_u.eps} \hspace{-2em} \includegraphics[width=0.36\textwidth]{exercise_neutral_figures/sp_v.eps} \hspace{-2em} \includegraphics[width=0.36\textwidth]{exercise_neutral_figures/sp_w.eps} \end{frame} \end{document}