updated: spalart allmaras documentation with some verification data
git-svn-id: http://svn.sintef.no/trondheim/IFEM/trunk@1263 e10b68d5-8a6e-419e-a041-bce267b0401d
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							@@ -1,20 +1,24 @@
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\documentclass[twoside, 11pt, a4paper]{article}
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\usepackage{amsmath,amsfonts,amssymb,graphicx,parskip}
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\usepackage[utf8]{inputenc}
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\usepackage{subfigure}
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\DeclareMathOperator{\eps}{\epsilon}
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\newcommand{\dee}{\mathrm{d}}
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\title{Spalart-Allmaras turbulence model - SplineFEM implementation}
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\title{Spalart-Allmaras turbulence model - IFEM implementation}
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\author{Arne Morten Kvarving}
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\begin{document}
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\maketitle
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This document describe the derivation of the weak form, and the associated
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Jacobian, for the Spalart-Allmaras turbulence model given in \cite{sa}.
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It is implemented in SplineFEM in the SpalartAllmaras
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Integrand, see src/Integrands/SpalartAllmaras.h/C, while
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you can find a test application (and SIM classes) in Apps/SpalartAllmaras.
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\section{Equations}
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Initial expression:
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\begin{equation}
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	\frac{\partial\tilde{\nu}}{\partial t} + \mathbf{u}\cdot\nabla\tilde{\nu} = c_{b1}\tilde{S}\tilde{\nu}+\frac{1}{\sigma}\left(\nabla\cdot\left(\nu + \tilde{\nu}\right)\nabla\tilde{\nu} + c_{b2}\left|\nabla\tilde{\nu}\right|^2\right) - c_{w1}f_w\left(\frac{\tilde{\nu}}{d}\right)^2.
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@@ -115,6 +119,73 @@ The weak form gives a simple mass term.
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\bf Weak form, second term:\rm \\
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Straight forward, no integration by parts have to be performed.
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\newpage
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\section{Verification}
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We have performed some verification studies to confirm that the model 
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The first one is a two-dimensional backward facing step with a sharp step. The grid and
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geometry definition can be found in Figure \ref{fig:bfsgrid}.
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\begin{figure}[h]
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    \begin{center}
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        \includegraphics[width=14cm]{bfs2dgrid}
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    \end{center}
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    \caption{The geometry (and) grid used for BFS2D code validation test. The grid consists of 18751 nodes.}
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    \label{fig:bfsgrid}
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\end{figure}
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The boundary conditions for the velocity and pressure are given in Figure \ref{fig:bfsupbc}.
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\begin{figure}[h]
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    \begin{center}
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        \includegraphics[width=14cm]{bfs2dupbc}
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    \end{center}
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    \caption{The boundary conditions for the velocity and pressure in the BFS2D code validation test.}
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    \label{fig:bfsupbc}
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\end{figure}
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\begin{figure}[h]
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    \begin{center}
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        \includegraphics[width=8cm]{inflow}
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    \end{center}
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    \caption{The inflow velocity profile.}
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    \label{fig:bfsinflow}
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\end{figure}
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The boundary conditions for the turbulent viscosity are given in Figure \ref{fig:bfsnutbc}.
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\begin{figure}[h]
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    \begin{center}
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        \includegraphics[width=14cm]{bfs2dnutbc}
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    \end{center}
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    \caption{The boundary conditions for the turbulent viscosity in the BFS2D code validation test.}
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    \label{fig:bfsnutbc}
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\end{figure}
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Some important parameters;
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\[
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    \begin{split}
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        u_{\infty} &= 1 \\
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        \nu &= 0.000331 \\
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        \rho &= 1 \\
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        Re &= 3025 \\
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        \Delta t &= 0.005
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    \end{split}
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\]
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The following results were obtained using a second order scheme with SUPG stabilization for both the
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turbulence model and the velocity solver. No substantial differences compared to the results without
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can be observed using the naked eye.
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\newpage
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\begin{figure}[h]
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    \begin{center}
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        \subfigure[$\frac{x}{S}=4$]{\includegraphics[width=5.5cm]{x0}}
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        \subfigure[$\frac{x}{S}=6$]{\includegraphics[width=5.5cm]{x2}}
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        \subfigure[$\frac{x}{S}=8$]{\includegraphics[width=5.5cm]{x4}}
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        \subfigure[$\frac{x}{S}=10$]{\includegraphics[width=5.5cm]{x6}}
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        \subfigure[$\frac{x}{S}=12$]{\includegraphics[width=5.5cm]{x8}}
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        \subfigure[$\frac{x}{S}=16$]{\includegraphics[width=5.5cm]{x12}}
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    \end{center}
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    \caption{Comparison of velocity profiles.}
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    \label{fig:bfsx1}
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\end{figure}
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\end{document}
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