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--- software:mag:start [2013/12/31 00:15]
emheien
+++ software:mag:start [2020/12/29 01:00] (current)
ljhwang
@@ Line 1: / Line 1: @@
 ====== MAG ======
+//This content has been moved to hubzero. LJ Hwang 2020.12.28//
 [[http://geodynamics.org/cig/software/mag|MAG Software Page]]
@@ Line 12: / Line 14: @@
 A high-resolution version of the above phenomenon. ({{:software:mag:magmv500.mov|original hi-res}}, {{:software:mag:magmv315l.mov|original low-res}})
+===== Tutorials =====
+The following tutorials demonstrate (1) how to run the prepackaged benchmark data, and (2) how to produce a magnetic field reversal.
+==== Prerequisites and Run Notes ====
+  * **Install MAG** - The following tutorials assume you have already installed MAG following the instructions in Chapter 2 in the [[http://geodynamics.org/cig/software/mag/mag_book.pdf|MAG User Manual]].
+  * **Delete, Move, or Rename Output Files** - After each run, you must delete, move, or rename all of the output files in the current directory before re-running with the same "output" filename. Retaining same-named output files in the current directory causes MAG to crash.
+  * **Changing Parameters** - Physical and time-step parameters can be changed in the par-file namelist without re-compiling MAG. See Appendix B in the [[http://geodynamics.org/cig/software/mag/mag_book.pdf|MAG User Manual]] for a list of the input parameter names and definitions. Grid parameters must be changed in param.f and MAG must be then re-compiled. There are some numerical restrictions on the grid parameter combinations, which are given in Appendix A.
+==== Tutorial 1: Running Benchmarks ====
+Uncompress all files, and create a path (see Chapter 2 of [[http://geodynamics.org/cig/software/mag/mag_book.pdf|MAG User Manual]])
+Link the grid parameter file to param.f, which enters into most subroutines through "include" statements. For example, a grid parameter file named 'param32f4.f' (32 is the spherical harmonics truncation degree; 4 is the longitude symmetry) is linked using:
+    $ ln -sf param32s4.f param.f
+Compile the program as follows (renaming the executable in line 2 is optional):
+    $ make
+    $ mv magx magx32s4
+MAG uses a standard input file. Background execute using par.XXX as the input file and .YYY as the output file's extension, e.g., '$ magx32s4 <par.XXX >p.YYY &', so to run with the benchmark input files (par.bnch0 or par.bnch1), the execution statement should be:
+    $ magx32s4 <par.bnch0 >p.bench0 &
+If there is a problem with the input file list, it is often the final three lines; with some systems, a "$" may be required at the end.
+MAG produces a series of output files. For example, when using input file par.bnch0 (the example in step 4) MAG generates: 'l.bench0, ls.bench0, g[i].bench0 and d[i].bench0', where i=0,1,2...9. See Appendix B in the [[http://geodynamics.org/cig/software/mag/mag_book.pdf|MAG User Manual]] for details on MAG's output files. Compare your output files with the data provided in the directory ~/bench-data/data_bench0.
+==== Tutorial 2: Reversal Dynamo Case ====
+In this example, we produce a magnetic field reversal using MAG. The input parameter in the source directory for this case is ~/src/par.Rev. There is no longitudinal symmetry in this case, so when you compile MAG, use param32s1.f linking to param.f. The Ekman number is E=0.02, the Prandtl number is Pr=1 and the magnetic Prandtl number is Pm=10. The Rayleigh number is Ra=12000.
+Link param32s1.f  to param.f:
+    $ ln -sf param32s1.f  param.f
+Compile the program with:
+    $ make
+    $ mv magx magx32s4
+Background execute using par.Rev as the input file and p.rev as the output file (Note: The output file's extension is specified in the par-file, e.g., here par.Rev specifies that the outfile should be named *filename*.rev):
+    $ magx32s4 <par.Rev >p.rev &
+MAG will then execute and produce datafiles in the same directory. See Appendix B in the [[http://geodynamics.org/cig/software/mag/mag_book.pdf|MAG User Manual]] for details on MAG's output files.
+=== Results and Discussion ===
+This case has run on 32-bit and 64-bit Intel processors. Figure 1 below shows a plot of mean velocity Vrms, mean magnetic field Brms, the axial dipole and the dipole tilt on the outer boundary. It indicated a magnetic field reversal between time steps 25 and 30.
+{{:software:mag:tutorial:field-64.gif?300|Figure 1}}
+Figure 2 shows a longer run of MAG, where we see the magnetic field reversed again. At this time, the magnetic field had weakened substantially.
+{{:software:mag:tutorial:field-64-revr.gif?300|Figure 2}}
+In Figures 3 and 4 (below), the top figure is the pole plot before the second field reversal and the bottom is the pole plot after the second field reversal.
+{{:software:mag:tutorial:g1revr.gif?300|Figure 3}}
+{{:software:mag:tutorial:g7revr.gif?300|Figure 4}}
+An additional tutorial on creating a Reversal Dynamo movie is found in Chapter 5 of the [[http://geodynamics.org/cig/software/mag/mag_book.pdf|MAG User Manual]].

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