File sheath_boundary_simple.hxx

Defines

SHEATH_BOUNDARY_SIMPLE_H

struct SheathBoundarySimple : public Component 

#include <sheath_boundary_simple.hxx>

Boundary condition at the wall in Y

This is a collective component, because it couples all charged species

This implements a simple boundary condition, where each species goes to their own sound velocity at the sheath entrance.

Notes:

It is recommended to use SheathBoundary rather than SheathBoundarySimple; this is here for comparison to that more complete model.

Public Functions

SheathBoundarySimple(std::string name, Options &options, Solver*)

Input options

<name> e.g. “sheath_boundary_simple”
- lower_y Boundary on lower y?
- upper_y Boundary on upper y?
- gamma_e Electron sheath heat transmission coefficient
- gamma_i Ion sheath heat transmission coefficient
- sheath_ion_polytropic Ion polytropic coefficient in Bohm sound speed. Default 1.
- wall_potential Voltage of the wall [Volts]
- secondary_electron_coef Effective secondary electron emission coefficient
- sin_alpha Sine of the angle between magnetic field line and wall surface (0 to 1)
- always_set_phi Always set phi field? Default is to only modify if already set

virtual void transform(Options &state) override

Inputs

species
- e
  - density
  - temperature
  - pressure Optional
  - velocity Optional
  - mass Optional
  - adiabatic Optional. Ratio of specific heats, default 5/3.
- <ions> if charge is set (i.e. not neutrals)
  - charge
  - mass
  - density
  - temperature
  - pressure Optional
  - velocity Optional. Default 0
  - momentum Optional. Default mass * density * velocity
  - adiabatic Optional. Ratio of specific heats, default 5/3.
fields
- phi Optional. If not set, calculated at boundary (see note below)

Outputs

species
- e
  - density Sets boundary
  - temperature Sets boundary
  - velocity Sets boundary
  - energy_source
- <ions>
  - density Sets boundary
  - temperature Sets boundary
  - velocity Sets boundary
  - momentum Sets boundary
  - energy_source
fields
- phi Sets boundary

If the field phi is set, then this is used in the boundary condition. If not set, phi at the boundary is calculated and stored in the state. Note that phi in the domain will not be set, so will be invalid data.

Private Members

BoutReal Ge

BoutReal sin_alpha

BoutReal gamma_e: Electron sheath heat transmission.

BoutReal gamma_i: Ion sheath heat transmission.

BoutReal sheath_ion_polytropic: Polytropic coefficient in sheat velocity.

bool lower_y

bool upper_y

bool always_set_phi: Set phi field?

Field3D wall_potential: Voltage of the wall. Normalised units.