/[MITgcm]/manual/s_examples/rotating_tank/tank.tex
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1 % $Header: /u/gcmpack/manual/part3/case_studies/rotating_tank/tank.tex,v 1.10 2004/10/13 18:52:17 afe Exp $
2 % $Name: $
3
4 \bodytext{bgcolor="#FFFFFFFF"}
5
6 %\begin{center}
7 %{\Large \bf Using MITgcm to Simulate a Rotating Tank in Cylindrical
8 %Coordinates}
9 %
10 %\vspace*{4mm}
11 %
12 %\vspace*{3mm}
13 %{\large May 2001}
14 %\end{center}
15
16 \section{A Rotating Tank in Cylindrical Coordinates}
17 \label{sect:eg-tank}
18 \label{www:tutorials}
19 \begin{rawhtml}
20 <!-- CMIREDIR:eg-tank: -->
21 \end{rawhtml}
22
23 This section illustrates an example of MITgcm simulating a laboratory
24 experiment on much smaller scales than those commonly considered in
25 geophysical
26 fluid dynamics.
27
28 \subsection{Overview}
29 \label{www:tutorials}
30
31
32 This example configuration demonstrates using the MITgcm to simulate
33 a laboratory demonstration using a rotating tank of water with an ice
34 bucket in the center. The simulation is configured for a laboratory
35 scale on a
36 $3^{\circ}$ $\times$ 20cm
37 cyclindrical grid with twenty-nine vertical
38 levels.
39 \\
40 example illustration from GFD lab here
41 \\
42
43
44
45
46
47 \subsection{Equations Solved}
48 \label{www:tutorials}
49
50
51 \subsection{Discrete Numerical Configuration}
52 \label{www:tutorials}
53
54 The domain is discretised with
55 a uniform cylindrical grid spacing in the horizontal set to
56 $\Delta a=1$~cm and $\Delta \phi=3^{\circ}$, so
57 that there are 120 grid cells in the azimuthal direction and thirty-one grid cells in the radial. Vertically the
58 model is configured with twenty-nine layers of uniform 0.5cm thickness.
59 \\
60 something about heat flux
61
62 \subsection{Code Configuration}
63 \label{www:tutorials}
64 \label{SEC:eg-baro-code_config}
65
66 The model configuration for this experiment resides under the
67 directory {\it verification/rotatingi\_tank/}. The experiment files
68 \begin{itemize}
69 \item {\it input/data}
70 \item {\it input/data.pkg}
71 \item {\it input/eedata},
72 \item {\it input/bathyPol.bin},
73 \item {\it input/thetaPol.bin},
74 \item {\it code/CPP\_EEOPTIONS.h}
75 \item {\it code/CPP\_OPTIONS.h},
76 \item {\it code/SIZE.h}.
77 \end{itemize}
78
79 contain the code customizations and parameter settings for this
80 experiments. Below we describe the customizations
81 to these files associated with this experiment.
82
83 \subsubsection{File {\it input/data}}
84 \label{www:tutorials}
85
86 This file, reproduced completely below, specifies the main parameters
87 for the experiment. The parameters that are significant for this configuration
88 are
89
90 \begin{itemize}
91
92 \item Line 10, \begin{verbatim} viscAh=5.0E-6, \end{verbatim} this line sets
93 the Laplacian friction coefficient to $6 \times 10^{-6} m^2s^{-1}$,
94 which is ususally
95 low because of the small scale, presumably.... qqq
96
97 \item Line 19, \begin{verbatim}f0=0.5 , \end{verbatim} this line sets the
98 coriolis term, and represents a tank spinning at 2/s
99 \item Line 20, \begin{verbatim} beta=1.E-11, \end{verbatim} this line sets
100 $\beta$ (the gradient of the coriolis parameter, $f$) to $10^{-11} s^{-1}m^{-1}$
101
102 \item Lines 27 and 28
103 \begin{verbatim}
104 rigidLid=.TRUE.,
105 implicitFreeSurface=.FALSE.,
106 \end{verbatim}
107
108 qqq these lines do the opposite of the following:
109 suppress the rigid lid formulation of the surface
110 pressure inverter and activate the implicit free surface form
111 of the pressure inverter.
112
113 \item Line 44,
114 \begin{verbatim}
115 nIter=0,
116 \end{verbatim}
117 this line indicates that the experiment should start from $t=0$
118 and implicitly suppresses searching for checkpoint files associated
119 with restarting an numerical integration from a previously saved state.
120
121 \item Line 47,
122 \begin{verbatim}
123 deltaT=0.1,
124 \end{verbatim}
125 This line sets the integration timestep to $0.1s$. This is an unsually
126 small value among the examples due to the small physical scale of the
127 experiment.
128
129 \item Line 58,
130 \begin{verbatim}
131 usingCylindricalGrid=.TRUE.,
132 \end{verbatim}
133 This line requests that the simulation be performed in a
134 cylindrical coordinate system.
135
136 \item Line 60,
137 \begin{verbatim}
138 dXspacing=3,
139 \end{verbatim}
140 This line sets the azimuthal grid spacing between each $x$-coordinate line
141 in the discrete grid. The syntax indicates that the discrete grid
142 should be comprise of $120$ grid lines each separated by $3^{\circ}$.
143
144
145
146 \item Line 61,
147 \begin{verbatim}
148 dYspacing=0.01,
149 \end{verbatim}
150 This line sets the radial cylindrical grid spacing between each $a$-coordinate line
151 in the discrete grid to $1cm$.
152
153 \item Line 62,
154 \begin{verbatim}
155 delZ=29*0.005,
156 \end{verbatim}
157 This line sets the vertical grid spacing between each z-coordinate line
158 in the discrete grid to $5000m$ ($5$~km).
159
160 \item Line 68,
161 \begin{verbatim}
162 bathyFile='bathyPol.bin',
163 \end{verbatim}
164 This line specifies the name of the file from which the domain
165 ``bathymetry'' (tank depth) is read. This file is a two-dimensional
166 ($a,\phi$) map of
167 depths. This file is assumed to contain 64-bit binary numbers
168 giving the depth of the model at each grid cell, ordered with the $\phi$
169 coordinate varying fastest. The points are ordered from low coordinate
170 to high coordinate for both axes. The units and orientation of the
171 depths in this file are the same as used in the MITgcm code. In this
172 experiment, a depth of $0m$ indicates an area outside of the tank
173 and a depth
174 f $-0.145m$ indicates the tank itself.
175
176 \item Line 67,
177 \begin{verbatim}
178 hydrogThetaFile='thetaPol.bin',
179 \end{verbatim}
180 This line specifies the name of the file from which the initial values
181 of temperature
182 are read. This file is a three-dimensional
183 ($x,y,z$) map and is enumerated and formatted in the same manner as the
184 bathymetry file.
185
186 \item Line qqq
187 \begin{verbatim}
188 tCyl = 0
189 \end{verbatim}
190 This line specifies the temperature in degrees Celsius of the interior
191 wall of the tank -- usually a bucket of ice water.
192
193
194 \end{itemize}
195
196 \noindent other lines in the file {\it input/data} are standard values
197 that are described in the MITgcm Getting Started and MITgcm Parameters
198 notes.
199
200 \begin{small}
201 \input{part3/case_studies/rotating_tank/input/data}
202 \end{small}
203
204 \subsubsection{File {\it input/data.pkg}}
205 \label{www:tutorials}
206
207 This file uses standard default values and does not contain
208 customizations for this experiment.
209
210 \subsubsection{File {\it input/eedata}}
211 \label{www:tutorials}
212
213 This file uses standard default values and does not contain
214 customizations for this experiment.
215
216 \subsubsection{File {\it input/thetaPol.bin}}
217 \label{www:tutorials}
218
219 The {\it input/thetaPol.bin} file specifies a three-dimensional ($x,y,z$)
220 map of initial values of $\theta$ in degrees Celsius. This particular
221 experiment is set to random values x around 20C to provide initial
222 perturbations.
223
224 \subsubsection{File {\it input/bathyPol.bin}}
225 \label{www:tutorials}
226
227
228 The {\it input/bathyPol.bin} file specifies a two-dimensional ($x,y$)
229 map of depth values. For this experiment values are either
230 $0m$ or {\bf -delZ}m, corresponding respectively to outside or inside of
231 the tank. The file contains a raw binary stream of data that is enumerated
232 in the same way as standard MITgcm two-dimensional, horizontal arrays.
233
234 \subsubsection{File {\it code/SIZE.h}}
235 \label{www:tutorials}
236
237 Two lines are customized in this file for the current experiment
238
239 \begin{itemize}
240
241 \item Line 39,
242 \begin{verbatim} sNx=120, \end{verbatim} this line sets
243 the lateral domain extent in grid points for the
244 axis aligned with the x-coordinate.
245
246 \item Line 40,
247 \begin{verbatim} sNy=31, \end{verbatim} this line sets
248 the lateral domain extent in grid points for the
249 axis aligned with the y-coordinate.
250
251 \end{itemize}
252
253 \begin{small}
254 \input{part3/case_studies/rotating_tank/code/SIZE.h}
255 \end{small}
256
257 \subsubsection{File {\it code/CPP\_OPTIONS.h}}
258 \label{www:tutorials}
259
260 This file uses standard default values and does not contain
261 customizations for this experiment.
262
263
264 \subsubsection{File {\it code/CPP\_EEOPTIONS.h}}
265 \label{www:tutorials}
266
267 This file uses standard default values and does not contain
268 customizations for this experiment.
269

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