- Timestamp:
- Sep 18, 2013 1:19:19 PM (11 years ago)
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palm/trunk/TUTORIAL/SOURCE/non_cyclic_boundary_conditions.tex
r945 r1226 66 66 \item<4->{Non-cyclic boundary conditions give problems:} 67 67 \begin{itemize} 68 \par\smallskip 68 69 \item<5->{If Dirichlet conditions (fixed vertical profiles) are used at the inflow, the inflow is laminar and some (significant) domain space is needed in order to develop turbulence.} 70 \par\smallskip 69 71 \item<6->{At the outflow, a boundary condition is required which allows the eddies to freely leave the domain.} 70 72 \end{itemize} … … 81 83 The main motivation for non-cyclic boundary conditions are studies of isolated phenomena. 82 84 \begin{tabbing} 83 \uncover<2->{\textbf{Example:} \= Turbulence generated by a single obstacle. \\} 85 \uncover<2->{\textbf{Example:} \= Turbulence generated by a single obstacle. \\} 86 \\ 84 87 \uncover<6->{ \> Cyclic boundary conditions along x would allow the generated turbulence\\ 85 88 \> to enter the domain again, and so finally to modify the turbulence \\ … … 87 90 \\ 88 91 \uncover<9>{ \> This wouldn't be a simulation of a single building, but of an\\ 89 \> infinite row of buildings! \\}92 \> infinite row of buildings! } 90 93 \end{tabbing} 91 94 \begin{center} 92 \includegraphics<3 >[width=0.7\textwidth]{non_cyclic_figures/motivation_non_cyclic_1.png}93 \includegraphics<4 >[width=0.7\textwidth]{non_cyclic_figures/motivation_non_cyclic_2.png}94 \includegraphics<5-6 >[width=0.7\textwidth]{non_cyclic_figures/motivation_non_cyclic_3.png}95 \includegraphics<7 >[width=0.7\textwidth]{non_cyclic_figures/motivation_non_cyclic_4.png}96 \uncover<8- >{\begin{center} \includegraphics[width=0.7\textwidth]{non_cyclic_figures/motivation_non_cyclic_5.png} \end{center}}95 \includegraphics<3|handout:0>[width=0.7\textwidth]{non_cyclic_figures/motivation_non_cyclic_1.png} 96 \includegraphics<4|handout:0>[width=0.7\textwidth]{non_cyclic_figures/motivation_non_cyclic_2.png} 97 \includegraphics<5-6|handout:0>[width=0.7\textwidth]{non_cyclic_figures/motivation_non_cyclic_3.png} 98 \includegraphics<7|handout:0>[width=0.7\textwidth]{non_cyclic_figures/motivation_non_cyclic_4.png} 99 \uncover<8-|handout:1>{\begin{center} \includegraphics[width=0.7\textwidth]{non_cyclic_figures/motivation_non_cyclic_5.png} \end{center}} 97 100 \end{center} 98 101 \normalsize … … 105 108 \onslide<2->{Using Dirichlet-conditions (e.g u(z) = const.), there is no turbulence at the inflow. $\rightarrow $the flow is laminar $\rightarrow$ LES approach fails!} 106 109 \par\bigskip 107 \includegraphics<3 >[width=0.8\textwidth]{non_cyclic_figures/implications_non_cyclic_1.png}108 \includegraphics<4 >[width=0.8\textwidth]{non_cyclic_figures/implications_non_cyclic_2.png}109 \uncover<5- >{\includegraphics[width=0.8\textwidth]{non_cyclic_figures/implications_non_cyclic_3.png}}110 \includegraphics<3|handout:0>[width=0.8\textwidth]{non_cyclic_figures/implications_non_cyclic_1.png} 111 \includegraphics<4|handout:0>[width=0.8\textwidth]{non_cyclic_figures/implications_non_cyclic_2.png} 112 \uncover<5-|handout:1>{\includegraphics[width=0.8\textwidth]{non_cyclic_figures/implications_non_cyclic_3.png}} 110 113 \par\bigskip 111 114 \onslide<6->{Flow internal turbulence may develop, but this may require a very long model domain.} 112 115 \par\bigskip 113 \includegraphics<7 >[width=\textwidth]{non_cyclic_figures/implications_non_cyclic_4.png}114 \includegraphics<8 >[width=\textwidth]{non_cyclic_figures/implications_non_cyclic_5.png}115 \uncover<9- >{\includegraphics[width=\textwidth]{non_cyclic_figures/implications_non_cyclic_6.png}}116 \includegraphics<7|handout:0>[width=\textwidth]{non_cyclic_figures/implications_non_cyclic_4.png} 117 \includegraphics<8|handout:0>[width=\textwidth]{non_cyclic_figures/implications_non_cyclic_5.png} 118 \uncover<9-|handout:1>{\includegraphics[width=\textwidth]{non_cyclic_figures/implications_non_cyclic_6.png}} 116 119 \onslide<10->{There is a need to supply turbulence information at the inflow.} 117 120 \end{frame} … … 128 131 \item<3->{by recycling-method (Lund et al., 1998)} 129 132 \end{itemize} 130 \includegraphics<4 >[width=\textwidth]{non_cyclic_figures/create_turbulent_inflow_1/create_turbulent_inflow_1_neu.png}131 \includegraphics<5 >[width=\textwidth]{non_cyclic_figures/create_turbulent_inflow_1/create_turbulent_inflow_2_neu.png}132 \includegraphics<6 >[width=\textwidth]{non_cyclic_figures/create_turbulent_inflow_1/create_turbulent_inflow_3_neu.png}133 \includegraphics<7 >[width=\textwidth]{non_cyclic_figures/create_turbulent_inflow_1/create_turbulent_inflow_4_neu.png}134 \includegraphics<8 >[width=\textwidth]{non_cyclic_figures/create_turbulent_inflow_1/create_turbulent_inflow_5_neu.png}135 \uncover<9- >{\includegraphics[width=\textwidth]{non_cyclic_figures/create_turbulent_inflow_1/create_turbulent_inflow_6.png}}133 \includegraphics<4|handout:0>[width=\textwidth]{non_cyclic_figures/create_turbulent_inflow_1/create_turbulent_inflow_1_neu.png} 134 \includegraphics<5|handout:0>[width=\textwidth]{non_cyclic_figures/create_turbulent_inflow_1/create_turbulent_inflow_2_neu.png} 135 \includegraphics<6|handout:0>[width=\textwidth]{non_cyclic_figures/create_turbulent_inflow_1/create_turbulent_inflow_3_neu.png} 136 \includegraphics<7|handout:0>[width=\textwidth]{non_cyclic_figures/create_turbulent_inflow_1/create_turbulent_inflow_4_neu.png} 137 \includegraphics<8|handout:0>[width=\textwidth]{non_cyclic_figures/create_turbulent_inflow_1/create_turbulent_inflow_5_neu.png} 138 \uncover<9-|handout:1>{\includegraphics[width=\textwidth]{non_cyclic_figures/create_turbulent_inflow_1/create_turbulent_inflow_6.png}} 136 139 \par\bigskip 137 140 \uncover<10>{How do we get the initial turbulence in the recycle area? \\ … … 236 239 \begin{itemize} 237 240 \item<2->{The \textbf{multigrid-method} has to be used for solving the Poisson-equation.} 238 \item<3->{A \textbf{damping zone} has sometimes to be activated in the vicinity of the outflow in order to avoid reflection of outgoinggravity waves.}241 \item<3->{A \textbf{damping zone} has sometimes to be activated in the vicinity of the in- and outflow in order to avoid reflection of gravity waves.} 239 242 \item<4->{\textbf{Volume flow conservation} should be activated, because otherwise flow acceleration or deceleration may occur along the non-cyclic direction.} 240 243 \item<5->{If turbulence recycling is not used, it may be neccessary to \textbf{continuously impose perturbations} on the horizontal velocity field in the vicinity of the … … 308 311 \item<2->{Restart data has to be output and output of instantaneous, horizontally averaged profiles has to be switched on and performed at the end of the run. 309 312 This enables writing of profiles to the restart file, which can then be used by the main run.} 313 \item<3->{Instead of using averaged profiles from the prerun, inflow profiles for the main run can also be prescribed using parameters u\_profile and v\_profile.} 310 314 \end{itemize} 311 315 \tikzstyle{box} = [rectangle, draw, text width=\textwidth, font=\small] … … 376 380 \begin{itemize} 377 381 \item<1->{Non-cyclic boundary conditions and turbulence recycling method require extreme care with setting of the respective parameters.} 378 \item<2->{So far, these methods have been applied only to a few special cases (cold air outbreaks ). Other setups may require modifications.}379 \item<3->{Biggest problems are caused by gravity waves in capping inversions. Simulations with pure neutral stratification are expected tocause less problems.}382 \item<2->{So far, these methods have been applied only to a few special cases (cold air outbreaks, urban canopy layer for neutral stratification). Other setups may require modifications.} 383 \item<3->{Biggest problems are caused by gravity waves in capping inversions. Simulations with pure neutral stratification cause less problems.} 380 384 \end{itemize} 381 385 \end{frame}
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