mpcd.fill¶

Overview

`GeometryFiller`	Virtual-particle filler for a bounce-back geometry.
`VirtualParticleFiller`	Base virtual-particle filler.

Details

MPCD virtual-particle fillers.

Virtual particles are MPCD particles that are added to ensure MPCD collision cells that are sliced by solid boundaries do not become “underfilled”. From the perspective of the MPCD algorithm, the number density of particles in these sliced cells is lower than the average density, and so the transport properties may differ. In practice, this usually means that the boundary conditions do not appear to be properly enforced.

class hoomd.mpcd.fill.GeometryFiller(type, density, kT, geometry)¶

Bases: VirtualParticleFiller

Virtual-particle filler for a bounce-back geometry.

Parameters:

type (str) – Type of particles to fill.
density (float) – Particle number density.
kT (hoomd.variant.variant_like) – Temperature of particles.
geometry (hoomd.mpcd.geometry.Geometry) – Surface to fill around.

Virtual particles are inserted in cells whose volume is sliced by the specified geometry. The algorithm for doing the filling depends on the specific geometry.

Example:

Filler for parallel plate geometry.

plates = hoomd.mpcd.geometry.ParallelPlates(separation=6.0)
filler = hoomd.mpcd.fill.GeometryFiller(
    type="A",
    density=5.0,
    kT=1.0,
    geometry=plates)
simulation.operations.integrator.virtual_particle_fillers = [filler]

geometry¶

Surface to fill around (read only).

Type:: hoomd.mpcd.geometry.Geometry

class hoomd.mpcd.fill.VirtualParticleFiller(type, density, kT)¶

Bases: Operation

Base virtual-particle filler.

Parameters:

type (str) – Type of particles to fill.
density (float) – Particle number density.
kT (hoomd.variant.variant_like) – Temperature of particles.

Virtual particles will be added with the specified type and density. Their velocities will be drawn from a Maxwell–Boltzmann distribution consistent with kT.

type¶

Type of particles to fill.

Example:

filler.type = "A"

Type:: str

density¶

Particle number density.

Example:

filler.density = 5.0

Type:: float

kT¶

Temperature of particles.

Examples:

Constant temperature.

filler.kT = 1.0

Variable temperature.

filler.kT = hoomd.variant.Ramp(1.0, 2.0, 0, 100)

Type:: hoomd.variant.variant_like