A CUDA-accelerated electromagnetostatics solver.
GPUfield is a small CUDA C program for calculating magnetic fields around direct current electromagnets.
GPUfield reads a pretty terse yet flexible scripting language that allows the user to define coil geometries in 3D space, and then take 2D slices of the resulting magnetic fields. It's pretty quick and dirty, but useful enough for designing coil geometries for earth's field NMR spectroscopy (EFNMR).
As an example, the following gpufield script computes the magnetic field around an 'infinitely' long wire:
current 1
moveto 0 0 -1e6
lineto 0 0 1e6
moveto 0 0 0
file 'field.dat'
grid z 1 1 256 256
clear
end
The resulting file field.dat will contain nine columns of data:
i x y z Bx By Bz |B|
where the indices i and j will run from 0 to 255, x and y will run
from -0.5 to 0.5, and z will equal 0. The components of the magnetic field
will be stored in Bx, By and Bz, and the magnitude of the field will be
stored in |B|. (This is just a simple example, of course)
The GPUfield program was spawned out of my search for a faster way to compute magnetic fields of direct current electromagnets than from the magnetic scalar potential. Finally, I ran across this paper:
Rashdi Shah Ahmad, Amiruddin Bin Shaari, Chew Teong Han, Magnetic Field Simulation of Golay Coil, Journal of Fundamental Sciences, 2008.
After seeing how much faster and simpler the computations could be, I had to write my own program. However, there's really no reason to burn CPU cycles on such an embarrassingly parallel problem, so I hooked into the NVIDIA CUDA API to accelerate the computations.
Sets the current for subsequent wires to 'i', in Amperes.
current [i]
Sets the filename for subsequent writes.
file '[filename]'
Moves the wire tracer to (x,y,z).
moveto [x] [y] [z]
Traces a line from the current location to (x,y,z).
lineto [x] [y] [z]
Draws a circle of 'n' segments along 'dir'.
circle [dir] [radius] [n]
Draws an arc of 'n' segments from angles 't1' to 't2' along 'dir'.
arc [dir] [radius] [t1] [t2] [n]
Draws a solenoid of 'n' line segments along 'dir'.
solenoid [dir] [radius] [pitch] [turns] [n]
Draws a helmholtz coil pair of 'n' segments along 'dir'.
helmholtz [dir] [radius] [pitch] [turns] [n]
Draws a maxwell coil triple of 'n' segments along 'dir'.
maxwell [dir] [radius] [pitch] [turns] [n]
Draws a golay coil of 'n' segments per arc with longitudinal axis +z and gradient axis 'dir'.
golay [dir] [a] [b] [c] [theta] [radius] [pitch] [turns] [n]
Computes the field along a straight line from the current point to (x,y,z), with 'n' equally spaced points along the line.
traj [x] [y] [z] [n]
Computes the field over a two-way grid having constant-dimension 'dim' and second- and third- dimension extents (u,v) and counts (unum,vnum).
grid [dim] [u] [v] [unum] [vnum]
Writes the current wire list to the current filename.
wires
Clears the wire list.
clear
Turns on verbose messages.
verbose
Turns off verbose messages.
quiet
Quits the application.
end
stop
quit
halt