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Changeset 3294 for trunk/DOC/TexFiles/Chapters/Annex_A.tex – NEMO

Ignore:
Timestamp:
2012-01-28T17:44:18+01:00 (12 years ago)
Author:
rblod
Message:

Merge of 3.4beta into the trunk

File:
1 edited

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  • trunk/DOC/TexFiles/Chapters/Annex_A.tex

    • Property svn:executable deleted
    r2282 r3294  
    1313% Chain rule 
    1414% ================================================================ 
    15 \section{Chain rule of $s-$coordinate} 
     15\section{The chain rule for $s-$coordinates} 
    1616\label{Apdx_A_continuity} 
    1717 
    18 In order to establish the set of Primitive Equation in curvilinear $s-$coordinates 
     18In order to establish the set of Primitive Equation in curvilinear $s$-coordinates 
    1919($i.e.$ an orthogonal curvilinear coordinate in the horizontal and an Arbitrary Lagrangian  
    2020Eulerian (ALE) coordinate in the vertical), we start from the set of equations established  
     
    6262% continuity equation 
    6363% ================================================================ 
    64 \section{Continuity Equation in $s-$coordinate} 
     64\section{Continuity Equation in $s-$coordinates} 
    6565\label{Apdx_A_continuity} 
    6666 
     
    128128Here, $w$ is the vertical velocity relative to the $z-$coordinate system.  
    129129Introducing the dia-surface velocity component, $\omega $, defined as  
    130 the velocity relative to the moving $s-$surfaces and normal to them: 
     130the volume flux across the moving $s$-surfaces per unit horizontal area: 
    131131\begin{equation} \label{Apdx_A_w_s} 
    132132\omega  = w - w_s - \sigma _1 \,u - \sigma _2 \,v    \\ 
     
    429429This formulation of the pressure gradient is characterised by the appearance of a term depending on the  
    430430the sea surface height only (last term on the right hand side of expression \eqref{Apdx_A_grad_p}). 
    431 This term will be abusively named \textit{surface pressure gradient} whereas the first term will be named  
     431This term will be loosely termed \textit{surface pressure gradient} 
     432whereas the first term will be termed the  
    432433\textit{hydrostatic pressure gradient} by analogy to the $z$-coordinate formulation.  
    433434In fact, the the true surface pressure gradient is $1/\rho_o \nabla (\rho \eta)$, and  
     
    451452To sum up, in a curvilinear $s$-coordinate system, the vector invariant momentum equation  
    452453solved by the model has the same mathematical expression as the one in a curvilinear  
    453 $z-$coordinate, but the pressure gradient term : 
     454$z-$coordinate, except for the pressure gradient term : 
    454455\begin{subequations} \label{Apdx_A_dyn_vect} 
    455456\begin{multline} \label{Apdx_A_PE_dyn_vect_u} 
     
    495496\end{subequations} 
    496497Both formulation share the same hydrostatic pressure balance expressed in terms of 
    497 hydrostatic pressure and density anmalies, $p_h'$ and $d=( \frac{\rho}{\rho_o}-1 )$: 
     498hydrostatic pressure and density anomalies, $p_h'$ and $d=( \frac{\rho}{\rho_o}-1 )$: 
    498499\begin{equation} \label{Apdx_A_dyn_zph} 
    499500\frac{\partial p_h'}{\partial k} = - d \, g \, e_3 
     
    502503It is important to realize that the change in coordinate system has only concerned 
    503504the position on the vertical. It has not affected (\textbf{i},\textbf{j},\textbf{k}), the  
    504 orthogonal curvilinear set of unit vector. ($u$,$v$) are always horizontal velocities 
     505orthogonal curvilinear set of unit vectors. ($u$,$v$) are always horizontal velocities 
    505506so that their evolution is driven by \emph{horizontal} forces, in particular  
    506507the pressure gradient. By contrast, $\omega$ is not $w$, the third component of the velocity, 
    507 but the dia-surface velocity component, $i.e.$ the velocity relative to the moving  
    508 $s-$surfaces and normal to them.  
     508but the dia-surface velocity component, $i.e.$ the volume flux across the moving  
     509$s$-surfaces per unit horizontal area.  
    509510 
    510511 
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