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PARTICLE_DOMAIN

Particle

*PARTICLE_DOMAIN
entype, enid, N${}_p$, $\mu$, $pfac$, $c_{dec}$, xsmooth, $t_{end}$
$x_0$, $y_0$, $z_0$, $x_1$, $y_1$, $z_1$
bc${}_{x0}$, bc${}_{y0}$, bc${}_{z0}$, bc${}_{x1}$, bc${}_{y1}$, bc${}_{z1}$
$\delta_0^{max}$, ctype, SPH${}_{uniform}$

Parameter definition

Variable
Description
entype
Structure entity type for particle structure interaction
options: P, PS, ALL
enid
Structure entity ID
N${}_p$
Total number of particles
$\mu$
Particle-structure contact friction
$pfac$
Particle-structure contact stiffness
$c_{dec}$
Impulse transfer smoothing time (gas-structure)
xsmooth
Spatial impulse smoothing level
default: inactive
$t_{end}$
Particle deactivation time
$x_0$
Particle domain minimum x-coordinate
$y_0$
Particle domain minimum y-coordinate
$z_0$
Particle domain minimum z-coordinate
$x_1$
Particle domain maximum x-coordinate
$y_1$
Particle domain maximum y-coordinate
$z_1$
Particle domain maximum z-coordinate
bc${}_{x0}$
Boundary condition at $x=x_0$
options:
0 $\rightarrow$ free
1 $\rightarrow$ rigid reflecting boundary
2 $\rightarrow$ fully clamped (SPH only)
bc${}_{y0}$
Boundary condition at $y=y_0$
options:
0 $\rightarrow$ free
1 $\rightarrow$ rigid reflecting boundary
2 $\rightarrow$ fully clamped (SPH only)
bc${}_{z0}$
Boundary condition at $z=z_0$
options:
0 $\rightarrow$ free
1 $\rightarrow$ rigid reflecting boundary
2 $\rightarrow$ fully clamped (SPH only)
bc${}_{x1}$
Boundary condition at $x=x_1$
options:
0 $\rightarrow$ free
1 $\rightarrow$ rigid reflecting boundary
2 $\rightarrow$ fully clamped (SPH only)
bc${}_{y1}$
Boundary condition at $y=y_1$
options:
0 $\rightarrow$ free
1 $\rightarrow$ rigid reflecting boundary
2 $\rightarrow$ fully clamped (SPH only)
bc${}_{z1}$
Boundary condition at $z=z_1$
options:
0 $\rightarrow$ free
1 $\rightarrow$ rigid reflecting boundary
2 $\rightarrow$ fully clamped (SPH only)
$\delta_0^{max}$
Max allowed initial contact penetration
default: 0
ctype
Particle-structure contact type
options:
0 $\rightarrow$ point to surface
1 $\rightarrow$ sphere to surface
SPH${}_{uniform}$
Flag to swith from uniform SPH node mass to uniform SPH smoothing length
options:
0 $\rightarrow$ uniform SPH node mass
1 $\rightarrow$ uniform SPH smoothing length

Description

This command is used to define a global domain and general settings for SPH and discrete particles. $N_p$ defines the total number of particles. The distribution of particles to the different sub-domains (PARTICLE_HE, PARTICLE_AIR, PARTICLE_SOIL, PARTICLE_SPH) is automatic.

The spatial impulse smoothing option smears out transferred impulses (in the particle-structure interaction) to more than one element face. xsmooth is an integer that defines the size of the region where impulses are distributed. xsmooth=1 means that only the direct neighbours of an impacted face will share a fraction of the impulse. With xsmooth=2 the impulse is distributed to both the direct and to the second level neighbours. Typical xsmooth parameters are in the range 1 to 10.

Particles overlapping the underlying Finite Element mesh by more than $\delta_0^{max}$ will be removed from the model during initialization.

When working with SPH and materials with significanlty different properties (density and/or stiffness), it is adviceable to set SPH${}_{uniform}$=1 and slide=1 (in PARTICLE_SPH). Sticking between materials with significanlty different properties is better modelled using MERGE than through SPH kernel function interactions.