Defining the domain

All simulations, whether using an embedded boundary (EB) or not, are specified on a simple cuboid domain. The low and high corners of the cuboid are defined by the prob_lo and prob_hi inputs.

The following inputs are defined using the prefix geometry:

	Description	Type	Default
coord_sys	Coordinate system used in simulation. Only Cartesian coordinates (coord_sys = 0) are supported.	Int	0
is_periodic	1 for true, 0 for false (one value for each coordinate direction)	Ints<3>	0 0 0
prob_lo	Low corner of physical domain (physical not index space)	Reals<3>	0 0 0
prob_hi	High corner of physical domain (physical not index space)	Reals<3>	0 0 0

Attention

MFIX-Exa geometry restrictions:

• There is no support for 1D or 2D simulation domains.

• Cartesian is the only supported coordinate system.

Mesh

The following inputs are defined using the prefix amr:

	Description	Type	Default
n_cell	Number of cells at level 0 in each coordinate direction.	Ints<3>	0 0 0

The base mesh spacing is computed for each direction by dividing the domain length by the number of cells. The mesh spacing is required to be the same in all directions:

\[\frac{\text{prob_hi[0] - prob_lo[0]}}{\text{n_cell[0]}} = \frac{\text{prob_hi[1] - prob_lo[1]}}{\text{n_cell[1]}} = \frac{\text{prob_hi[2] - prob_lo[2]}}{\text{n_cell[2]}}\]

The inputs for defining the mesh for a single-level simulation are demonstrated in the following example and illustrated in Fig. 1. In this example, the domain is a \(4 \times 1 \times 1\) cuboid, and there are \(32 \times 8 \times 8\) cells in the X, Y, and Z directions, respectively. The result is a uniform mesh spacing of \(0.125\) m in all three directions.

Listing 1 Snippet of intpus for mesh example. This is not a complete input file.

# Define periodicity and domain extents
# -------------------------------------------------------------
geometry.coord_sys   =  0           # Cartesian coordinates
geometry.is_periodic =  0   0   0   # periodicity for each direction
geometry.prob_lo     =  0.  0.  0   # lo corner of physical domain.
geometry.prob_hi     =  4.  1.  1.  # hi corner of physical domain

# Define the maximum level of refinement and number of cells
# -------------------------------------------------------------
amr.n_cell = 32  8  8

Fig. 1 Example of a single-level mesh.

Warning

MFIX-Exa simulations with a non-uniform mesh will not run.