Electromagnetic Field Simulator

A 3D FDM electromagnetic solver with real-time visualization. Inputs into the simulation are time-varying charge density and current density fields. Boundaries are absorbing. A CPU implementation (NumPy) and a GPU implementation (PyCUDA) are available.

This is a work in progress. Currently the CUDA implementation only follows Gauss's and Ampere's laws. NumPy implementation is complete, but unverified.

An incomplete simulation of a dipole radiator

Usage

Refer to example.py for a concrete example that was used to render the simulation shown above.

Solver

1. Create an EM field domain

from src import emfield

field = emfield.Field(
    size,       # Grid size [x size, y size, z size],
    scale,      # Spatial resolution
    timestep,   # Time resolution
    compute     # Solver implementation, "numpy" or "cuda"
)

2. Modify the charge density and current density fields

field.charge_density[...] = 0   # 3D scalar field,
                                # NumPy array (x size, y size, z size)

field.current_density[...] = 0  # 3D vector field,
                                # NumPy array (x size, y size, z size, 3)

3. Compute a simulation time step

field.update()

4. Retrieve resulting E and B fields

E_field = field.efield[1, ...]  # 3D vector field,
                                # NumPy array (x size, y size, z size, 3)

B_field = field.bfield[1, ...]  # 3D vector field,
                                # NumPy array (x size, y size, z size, 3)

# efield[0, ...] and bfield[0, ...] contain the previous values
# of the fields

Visualization

1. Create a window

from src import gui, fieldvis

window = gui.Window(
    size    # Size in pixels [width, height]
)

2. Create a visualizer instance

visualizer = fieldvis.FieldVisualizer(
    field   # EM field domain
)

3. Clear the window

window.fill(
    color=[0, 0, 0] # Integer color values from 0 to 255 [R, G, B]
)

4. Render a slice of the domain into a 2D pixel array

array = visualizer.eFieldRgb(
    index,      # Index (depth) of the desired 2D slice
    axis,       # Axis along which to slice (0: x, 1: y, 2: z)
    intensity   # Brightness scale
    )

5. Draw the array onto the window

window.drawArray(
    array,      # 2D pixel array
    size,       # Scale of the drawn array as a factor of window size
                # from 0 to 1 [x scale, y scale]
    position    # Position of the drawn array as a factor of window size
                # from 0 to 1 [x position, y position]
)

6. Throttle the refresh rate

window.sleep(
    fps # Desired frames per second (or slower if simulation cannot keep up)
)

6. Refresh the window

# Boolean, False if exit button was pressed, True otherwise
app_continue = window.update()

7. Close the window

window.close()

Available visualization functions

Function	Description	Formula
FieldVisualizer.eFieldRgb	E (vector) field	R,G,B = intensity * X,Y,Z
FieldVisualizer.bFieldRgb	B (vector) field	R,G,B = intensity * X,Y,Z
FieldVisualizer.eFieldMagnitude	E magnitude (scalar) field	R=G=B = intensity * |X,Y,Z|
FieldVisualizer.bFieldMagnitude	B magnitude (scalar) field	R=G=B = intensity * |X,Y,Z|
FieldVisualizer.chargeDensity	Charge density (scalar) field	R = intensity * |X| * (X > 0) G = 0 B = intensity * |X| * (X < 0)
FieldVisualizer.currentDensity	Current density (vector) field	R,G,B = intensity * X,Y,Z
FieldVisualizer.chargeDensityTransparent	Charge density (scalar) field	R = (X > 0) G = 0 B = (X < 0) A = intensity * |X|
FieldVisualizer.currentDensityTransparent	Current density (vector) field	R,G,B = X,Y,Z / |X,Y,Z| A = intensity * |X,Y,Z|