Run MagneX

In order to run a new simulation:

  1. Create a new directory, where the simulation will be run

  2. Make sure the MagneX executable is copied into this directory

  3. Add an inputs file to the directory

  4. Run

To run the executable, e.g. with MPI:

cd <run_directory>

# run with an inputs file:
mpiexec -n <num_mpi_ranks> ./<MagneX_executable> <input_file>

Simple Testcase Example

You can run the following to simulate muMAG Standard Problem 4 dynamics:

./main3d.gnu.MPI.ex standard_problem_inputs/inputs_std4

Inputs

An input file contains the numerical and physical parameters that define the situation to be simulated.

Many sample inputs files can be found in MagneX/Exec, MagneX/Exec/regression_inputs, and MagneX/Exec/standard_problem_inputs.

A list of parameters, with descriptions, can be found in MagneX/Source/MagneX.cpp. Also, MagneX uses a python-style parser for material properties and external bias field; see MagneX/Source/Initialization.cpp.

Outputs

By default, MagneX will write a status update to the terminal (stdout). Based on plot_int the code will also write out plotfiles. Refer to the following link for several visualization tools that can be used for AMReX plotfiles.

Specific Example: Data Analysis with yt

You can extract simulation data in numpy array format using yt:

import yt
ds = yt.load('./plt00010000/')  # for data at time step 10000
ad0 = ds.covering_grid(level=0, left_edge=ds.domain_left_edge, dims=ds.domain_dimensions)
Mx_array = ad0['Mx'].to_ndarray()  # x-component of magnetization

For more details on data extraction with yt, see the covering grid documentation.

Specific Run Examples

The following examples show how to run MagneX with different build configurations:

GNU Make builds (from Exec directory):

./main3d.gnu.MPI.ex standard_problem_inputs/inputs_std4

CMake builds (from project root directory):

CPU build (NOACC backend):

./build/main3d.gnu.MPI.ex Exec/standard_problem_inputs/inputs_std4

OpenMP build:

./build/main3d.gnu.MPI.OMP.ex Exec/standard_problem_inputs/inputs_std4

CUDA build:

./build/main3d.gnu.MPI.CUDA.ex Exec/standard_problem_inputs/inputs_std4

Using the convenience symlink:

./build/magnex Exec/standard_problem_inputs/inputs_std4