Dimensionality

This section describes the handling of dimensionality in WarpX. The velocity space is always three-dimensional: regardless of the dimensionality of the configuration space (position space), particles always carry three velocity (or momentum) components.

Build Options

Dimensions	CMake Option
3D	WarpX_DIMS=3 (default)
2D	WarpX_DIMS=2
1D	WarpX_DIMS=1
RZ	WarpX_DIMS=RZ
RCYLINDER	WarpX_DIMS=RCYLINDER
RSPHERE	WarpX_DIMS=RSPHERE

Note that one can build multiple WarpX dimensions at once via -DWarpX_DIMS="1;2;3;RZ;RCYLINDER;RSPHERE".

See building from source for further details.

Defines

Depending on the build variant of WarpX, the following preprocessor macros will be set:

Macro	3D	2D	1D	RZ	RCYLINDER	RSPHERE
AMREX_SPACEDIM	3	2	1	2	1	1
WARPX_DIM_3D	defined	undefined	undefined	undefined	undefined	undefined
WARPX_DIM_1D_Z	undefined	undefined	defined	undefined	undefined	undefined
WARPX_DIM_XZ	undefined	defined	undefined	undefined	undefined	undefined
WARPX_DIM_RZ	undefined	undefined	undefined	defined	undefined	undefined
WARPX_DIM_RCYLINDER	undefined	undefined	undefined	undefined	defined	undefined
WARPX_DIM_RSPHERE	undefined	undefined	undefined	undefined	undefined	defined
WARPX_ZINDEX	2	1	0	1	undefined	undefined

At the same time, the following conventions will apply:

Convention	3D	2D	1D	RZ	RCYLINDER	RSPHERE
Fields
AMReX Box dimensions	3	2	1	2	1	1
WarpX axis labels	x, y, z	x, z	z	x, z	r	r
Particles
AMReX .pos()	0, 1, 2	0, 1	0	0, 1	0	0
WarpX position names	x, y, z	x, z	z	r, z	r	r
extra SoA attribute				theta	theta	theta, phi

Please see the following sections for particle SoA details.

Conventions

In 2D, we assume that the position of a particle in y is equal to 0. In 1D, we assume that the position of a particle in x and y is equal to 0.