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| 6 | <title>PALM chapter 3.0</title> |
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| 8 | <meta name="AUTHOR" content="Marcus Oliver Letzel"> |
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| 11 | <meta name="KEYWORDS" content="parallel LES model"> |
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| 18 | <body dir="ltr" lang="en-US"> |
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| 19 | <h2 style="font-style: normal; line-height: 100%;"><font size="4">3.0 |
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| 20 | Execution of model runs</font></h2> |
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| 21 | <p style="line-height: 100%;">Given that the model was |
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| 22 | installed by the user (look at <a href="chapter_5.0.html">chapter |
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| 23 | 5.0</a>) and that it is clear, which phenomenon is to be simulated, |
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| 24 | there is a whole set of questions which must be answered before |
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| 25 | executing |
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| 26 | the actual application run, e.g.: </p> |
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| 27 | <ul> |
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| 28 | <li> |
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| 29 | <p |
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| 30 | style="margin-bottom: 0cm; font-style: normal; line-height: 100%;">How |
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| 31 | large does the model domain have to be and what grid size does |
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| 32 | phenomenon to be simulated require? </p> |
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| 33 | </li> |
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| 34 | <li> |
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| 35 | <p |
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| 36 | style="margin-bottom: 0cm; font-style: normal; line-height: 100%;">How |
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| 37 | long is the time which should be simulated, i.e. which typical time |
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| 38 | scale does the phenomenon have? </p> |
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| 39 | </li> |
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| 40 | <li> |
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| 41 | <p |
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| 42 | style="margin-bottom: 0cm; font-style: normal; line-height: 100%;">Which |
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| 43 | boundary conditions and initial conditions are to be selected? </p> |
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| 44 | </li> |
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| 45 | <li> |
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| 46 | <p style="font-style: normal; line-height: 100%;">Which model |
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| 47 | output data are necessary at which points in time, in order to be able |
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| 48 | to analyze the phenomenon afterwards? </p> |
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| 49 | </li> |
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| 50 | </ul> |
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| 51 | <p style="line-height: 100%;">The answers to these questions |
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| 52 | substantially determine the choice of values for the most important |
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| 53 | model parameters, with which the model run is steered. All possible |
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| 54 | parameters are described in chapters <a href="chapter_4.1.html">4.1</a>, |
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| 55 | <a href="chapter_4.2.html">4.2</a> |
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| 56 | and <a href="chapter_4.3.html">4.3</a>. |
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| 57 | The basic steering of the model with these parameters is explained in |
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| 58 | the introduction to <a href="chapter_4.0.html">chapter |
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| 59 | 4</a>. The user will rarely use all model parameters, since many are |
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| 60 | preset with consistent default values and therefore do not have to be |
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| 61 | changed by the user. Some of the most important parameters are not |
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| 62 | preset with default values and must be adjusted by the user in each |
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| 63 | case. Such a typical, minimum parameter set is described in <a |
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| 64 | href="chapter_4.4.html">chapter |
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| 65 | 4.4</a>. For the subsequent analysis of model runs, graphical |
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| 66 | visualization of model data is particularly important. <a |
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| 67 | href="chapter_4.5.html">Chapter |
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| 68 | 4.5</a> describes, how such outputs are produced with the model. </p> |
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| 69 | <p style="line-height: 100%;">The selected parameters and their values |
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| 70 | have to be supplied to the model as an input file. The |
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| 71 | structure of this file is described in the introduction to <a |
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| 72 | href="chapter_4.0.html">chapter |
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| 73 | 4</a>. The data, produced by the model, are located in a number of |
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| 74 | different output files. The model works with relative file names |
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| 75 | (i.e. without absolute path information). Thus all input and output |
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| 76 | files are |
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| 77 | expected and put in the directory, in which the actual model (the |
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| 78 | executable program created from the FORTRAN source code) is started |
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| 79 | (but also see next paragraph). |
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| 80 | All user-relevant input and output files are described in <a |
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| 81 | href="chapter_3.4.html">chapter |
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| 82 | 3.4</a>. </p> |
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| 83 | <p style="line-height: 100%;">The actual model (the executable |
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| 84 | program) is not started directly via the user, but with the help of |
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| 85 | the shell script <a |
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| 86 | href="http://www.muk.uni-hannover.de/institut/software/mrun_beschreibung.html">mrun</a>,which |
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| 87 | can be called by the user. This script takes over the entire pre- and |
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| 88 | postprocessing work, which is necessary for a model run. In addition |
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| 89 | to this, it generates e.g. automatically batch jobs for model runs on |
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| 90 | remote computers, provides for the appropriate file transfers of the |
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| 91 | input and output files to these computers, secures data on existing |
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| 92 | archives systems, starts if necessary restart jobs, and much more. |
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| 93 | <span style="font-weight: bold;">mrun</span> allows to specify |
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| 94 | individual path names for each simulation and |
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| 95 | for the different types of input/output files. The start of model runs |
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| 96 | with <b>mrun</b> is described in <a href="chapter_3.1.html">chapter |
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| 97 | 3.1</a>. </p> |
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| 98 | <p style="line-height: 100%;">The implementation of user code |
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| 99 | extensions in |
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| 100 | the model is made possible by a set of defined interfaces. You will |
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| 101 | find references to the programming of such extensions in <a |
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| 102 | href="chapter_3.5.html">chapter |
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| 103 | 3.5</a>. Frequently errors arise during the execution of the model |
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| 104 | after such changes, which can often be found only by interactive |
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| 105 | model steering and error tracing (debugging), which are described in |
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| 106 | <a href="chapter_3.6.html">chapter |
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| 107 | 3.6</a>. </p> |
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| 108 | <hr> |
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| 109 | <p style="font-style: normal; line-height: 100%;"><br> |
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| 110 | <font color="#000080"><font color="#000080"><a href="chapter_2.0.html"><font |
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| 118 | </p> |
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| 119 | <p style="font-style: normal; line-height: 100%;"><span |
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| 120 | style="font-style: italic;">Last change:</span> 14/04/05 (SR)<br> |
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