radarfdtd.txt

The purpose of this program is to enable building a config file to the radarFDTD package using a mo

NAME
    radarFDTD - a full 3D simulation of electromagnetic waves with efficient
    absorbing boundary conditions

SYNOPSIS
    radarFDTD directory [configuration file]

DESCRIPTION
    When started the program needs a directory as a command line parameter.
    If there is no second parameter defined it assumes the file is named
    sim.cfg. After starting it will output quite a few informations about
    the simulation it is going to start. The most important part is the
    section about memory, do not try to run the program in the swap area,
    since this will surely slow it down and may risk your hard disk which
    may start to smoke after a few weeks of hard work :-(.

CONFIGURATION FILE
    In this section there will be a short description of all sections within
    the file sim.cfg. Feel free to experiment with those settings, but do
    not blame me, if something goes entirely wrong... ;-)

    Since I am not a native English speaker, I hope you are not offended if
    I left some mistakes in here.

    Last thing, before we start: all lines which are empty or have a leading
    pound sign '#' are ignored (BTW, can someone explain to me why this
    double cross is called pound sign?).

  VERSION NUMBER
      # version number is...
      3

    This just states the version number this configuration file was written
    for. This is checked by the program and if it does not match the
    internal layout, it will not use it.

  MEMORY
      # maximum number of bytes the program may allocate
      100000000

    This is the number of bytes the program is allowed to allocate. Please
    change this according to your own need (or the memory limits of your
    computer; remember: this limit should be less than the physical amount
    of memory installed)

  MAXIMUM PML CONDUCTIVITY
      # insert maximum pml conductivity here [S/m]
      0.025

    There is a fixed equation which rules the rise of conductivity. If you
    are interested in a more detailed explanation, have a look at the paper
    of Fang and Wu from 1996 (citation can be found in the README file). As
    a good first guess try something between 10 and 50 mS/m, which should be
    reasonable good.

  MAXIMUM STRETCHING
      # insert maximum pml-stretching here [1]
      4.0

    Stretching should prevent evanescent waves to keep on moving within the
    perfectly matched layers, do not use too high values here, 2 to 4 seems
    to be quite reasonable.

  STEEPNESS
      # insert steepness here
      2.0

    The higher the value for steepness is, the less reflection will occur at
    the boundary between the simulation space and the absorbing layer which
    is generally a good thing. But unfortunately a high value here means
    that there will be a high reflection before a wave manages to reach the
    layer, which is a PEC (perfectly conducting layer)

  SIMULATION LENGTH
      # Length of Simulation [s]
      30.0e-9

    This just states the overall time duration of the simulation in seconds.
    Do not try to run a simulation too long, i.e. for a few seconds if your
    simulation space is only a few meters wide... it will take ages

  SIZE OF SIMULATION SPACE
      # size of simulation space (number of boxes in x-, y- and z-direction, respectively
      41 41 41

    These three numbers specify how man cells are used in each direction
    (let us call them x,y and z for the time being). I usually use odd
    numbers, so I can place the transmitter in the very middle of the
    simulation box, but handle this as you like to

  CELL SIZES
      # real size of a box [m] (x,y,z)
      0.025 0.025 0.025

    Here you specify how big (or small) a single Yee-cell should be, in this
    example this is about 2.5 cm (which is roughly an inch ;-)). Be careful
    with this selection, since you should have at least 10 boxes per main
    wavelength you want to simulate, otherwise you might get strange wavy
    things out of the simulation.

  TIME STEP SIZE
      # this number is a bit special: if positive it is the size of a time steps in seconds,
      # if negative, a matching time step is computed via the Courant-criterion
      # and finally divided by this number, i.e.