Compile-time options¶

Compile-time options are set in the case’s GNUmakefile (Setting up a case) or on the make command line, for example make -j4 DIM=3 USE_OMP=TRUE. Changing one requires a rebuild. Everything else is chosen at run time (Run-time options).

Model¶

The model is fixed at compile time because the number of state variables differs between models. Each option is a line DEFINES += -D<NAME>=<value> in the GNUmakefile. When a line is absent, the default in include/Macros.H applies.

Option	Values	Default	Meaning
`DEFINES += -DPHYSICS=`	`FIVEEQS`, `FIVEEQS_NPHASE`, `SIXEQS`, `SIXEQS_IE_NPHASE`	`FIVEEQS`	multiphase model (Models and equations)
`DEFINES += -DNPHASE=`	integer	`2`	number of phases for the N-phase models
`DEFINES += -DADVECTION=`	`true` / `false`	`true`	hyperbolic fluxes
`DEFINES += -DDIFFUSION=`	`true` / `false`	`false`	viscous and conductive fluxes
`DEFINES += -DNONCONSERVATIVE=`	`true` / `false`	`true`	non-conservative terms of the model

ADVECTION and NONCONSERVATIVE are normally left true. DIFFUSION=true applies to every model; the six-equation models give each phase its own stress and heat flux (Viscous and conductive fluxes in the six-equation models). NPHASE is used by FIVEEQS_NPHASE and SIXEQS_IE_NPHASE. The two-phase models ignore it.

The number of state variables in $d$ dimensions is

`PHYSICS`	State variables	Count
`FIVEEQS`	$\alpha_1\rho_1,\ \alpha_2\rho_2,\ \rho\vec u,\ \rho E,\ \alpha_1$	$4+d$
`FIVEEQS_NPHASE`	$\alpha_k\rho_k\ (k=1..N),\ \rho\vec u,\ \rho E,\ \alpha_k\ (k=1..N)$	$2N+d+1$
`SIXEQS`	$\alpha_1\rho_1,\ \alpha_2\rho_2,\ \rho\vec u,\ \alpha_1\rho_1E_1,\ \alpha_2\rho_2E_2,\ \alpha_1$	$5+d$
`SIXEQS_IE_NPHASE`	$\alpha_k,\ \alpha_k\rho_k,\ \alpha_k\rho_ke_k\ (k=1..N),\ \rho\vec u,\ \rho E$	$3N+d+1$

The names of these variables in plotfiles and refinement criteria are listed under Output variables.

Build¶

These are AMReX build options, set as NAME = value lines in the GNUmakefile.

Option	Values	Meaning
`DIM`	`2`, `3`	spatial dimension
`USE_MPI`, `USE_OMP`	`TRUE` / `FALSE`	parallel backends
`USE_CUDA`, `USE_HIP`, `USE_SYCL`	`TRUE` / `FALSE`	GPU backend
`DEBUG`	`TRUE` / `FALSE`	debug build with assertions and array bounds checks, run with checkpoints off (`amr.chk_int = -1`)

The case GNUmakefiles also set COMP = gnu, PRECISION = DOUBLE and PROFILE = FALSE, which are passed to the AMReX build system unchanged. How the executable name records these options is described under The executable name.

Paths¶

exec/Make.exec, which every case includes, sets two paths.

Variable	Default	Meaning
`COMPAS_HOME`	the repository that contains `exec/Make.exec`	COMPAS source tree
`AMREX_HOME`	`$(COMPAS_HOME)/../amrex`, a checkout next to COMPAS	AMReX source tree

Both can be set in the environment or on the make line. A case kept outside the repository includes $(COMPAS_HOME)/exec/Make.exec and is built with make COMPAS_HOME=/path/to/COMPAS (Starting a new case).

Macros in the case files¶

Some options are macros defined in the case’s prob/ProblemICBC.H instead of the GNUmakefile. They enable the optional hooks for source terms, boundary conditions, refinement and output, described under Optional hooks, and the error norms of a convergence study (CONVERGENCE), described under Convergence studies.

`PHYSICS`	State variables	Count
`FIVEEQS`	\(\alpha_1\rho_1,\ \alpha_2\rho_2,\ \rho\vec u,\ \rho E,\ \alpha_1\)	\(4+d\)
`FIVEEQS_NPHASE`	\(\alpha_k\rho_k\ (k=1..N),\ \rho\vec u,\ \rho E,\ \alpha_k\ (k=1..N)\)	\(2N+d+1\)
`SIXEQS`	\(\alpha_1\rho_1,\ \alpha_2\rho_2,\ \rho\vec u,\ \alpha_1\rho_1E_1,\ \alpha_2\rho_2E_2,\ \alpha_1\)	\(5+d\)
`SIXEQS_IE_NPHASE`	\(\alpha_k,\ \alpha_k\rho_k,\ \alpha_k\rho_ke_k\ (k=1..N),\ \rho\vec u,\ \rho E\)	\(3N+d+1\)