Simulate with complex geometries and complex physics
%BND_COLLISION%
velocity boundary condition to represent collisions
Boundary condition to be used for the collisional dynamics in the DROPLETPHASE solver (see DropletCollisions)
BND_COLLISION is a velocity boundary condition for particles within a DROPLETPHASE chamber. Particle dynamic when colliding with a boundary element with this boundary condition is modeled as a mass spring damper model. Additionally, an adhesive force can be applied, friction can be incorporated, energy dissipated at the boundary element can be modeled and a model for the roughness of the boundary element can be employed.
The adhesion/collision model is determined by the first five parameters k_n, e_n, E_a, R_a, mu (see DropletCollisions).
| Parameter | Meaning | Possible Values | Default |
|---|---|---|---|
| k_n | Spring Constant for particle interaction | k_n >= 0.0 | 0.0 (no collision modeling) |
| e_n | if 0 <= e_n <= 1 Coefficient of Restitution (0 ideal plastic, 1.0 ideal elastic), if e_n < 0, negative value of the damping coefficient | between 0 and 1 or negative | 0.0 |
| E_a | Adhesive potential difference relative to the particle mass | non-negative | 0.0 (no adhesion) |
| R_a | Broadness of zone of attraction relative to d30 | non-negative | 1.0 |
| mu | Friction Coefficient | non-negative | 0.0 (off) |
| SplitFactor | Fraction of total dissipated energy in collision dissipated at wall | 0.0 <= SplitFactor <= 1.0 | 0.0 (no energy dissipated at wall) |
| theta | Roughness: maximum angle of random perturbance of normals | 0.0 <= theta <= pi/2 | 0.0 (no roughness) |
| fac_PushBack | Push back factor relative to %ind_d30%: In case of %ind_OrganizeDTB% equal %waspushedback% the particle center is moved to the interior of the computation domain by fac_PushBack times %ind_d30% | 0.0 (no PushBack) <= 1 | 0.5 (particles do not overlap) |
Additionally for particle boundary interaction, the two parameters SplitFactor and theta may be specified:
- SplitFactor determines the fraction of energy dissipated by the wall: The energy calculated within the collision is split up between particle and wall in the given ratio.
- theta is given, the boundary normals will be randomly perturbed in order to model surface roughness. The value of theta, \( \theta\in\lbrack 0, \frac{\pi}{2} \rbrack\), determines the maximum angle between the modified normal vector \( {\bf n^*}\) and the original one \( {\bf n}\):
