numerical_dissipation

force_minimum_pdf_value!(f, minval)

Set a minimum value for the pdf-sized array f. Any points less than the minimum are set to the minimum. By default, no minimum is applied. The minimum value can be set by

[ion_numerical_dissipation]
force_minimum_pdf_value = 0.0

force_minimum_pdf_value_neutral!(f, minval)

Set a minimum value for the neutral-pdf-sized array f. Any points less than the minimum are set to the minimum. By default, no minimum is applied. The minimum value can be set by

[neutral_numerical_dissipation]
force_minimum_pdf_value = 0.0

Add diffusion in the r direction to suppress oscillations

Disabled by default.

The diffusion coefficient is set in the input TOML file by the parameter

[ion_numerical_dissipation]
r_dissipation_coefficient = 0.1

Note that the current distributed-memory compatible implementation does not impose a penalisation term on internal or external element boundaries

Add diffusion in the r direction to suppress oscillations for neutrals

Disabled by default.

The diffusion coefficient is set in the input TOML file by the parameter

[neutral_numerical_dissipation]
r_dissipation_coefficient = 0.1

Note that the current distributed-memory compatible implementation does not impose a penalisation term on internal or external element boundaries

Define the dissipation parameters for each species, which means there need to be three sections in each input file that specify the parameters required of each species, as follows:

[ion_numerical_dissipation]
vpa_dissipation_coefficient
...

[electron_numerical_dissipation]
vpa_dissipation_coefficient
...

[neutral_numerical_dissipation]
vz_dissipation_coefficient
...

There will still be the -1.0 default parameters.

Suppress the distribution function by damping towards a Maxwellian in the last element before the vpa boundaries, to avoid numerical instabilities there.

Disabled by default.

The damping rate is set in the input TOML file by the parameter

[ion_numerical_dissipation]
vpa_boundary_buffer_damping_rate = 0.1

Suppress the distribution function by applying diffusion in the last element before the vpa boundaries, to avoid numerical instabilities there.

Disabled by default.

The maximum diffusion rate in the buffer is set in the input TOML file by the parameter

[ion_numerical_dissipation]
vpa_boundary_buffer_diffusion_coefficient = 0.1

Try to suppress oscillations near the boundary by ensuring that every point in the final element is ≤ the innermost value. The distribution function should be decreasing near the boundaries, so this should be an OK thing to force.

Note: not currently used.

Add diffusion in the vpa direction to suppress oscillations

Disabled by default.

The diffusion coefficient is set in the input TOML file by the parameter

[ion_numerical_dissipation]
vpa_dissipation_coefficient = 0.1

Add diffusion in the vperp direction to suppress oscillations

Disabled by default.

The diffusion coefficient is set in the input TOML file by the parameter

[ion_numerical_dissipation]
vperp_dissipation_coefficient = 0.1

Add diffusion in the vz direction to suppress oscillations for neutrals

Disabled by default.

The diffusion coefficient is set in the input TOML file by the parameter

[neutral_numerical_dissipation]
vz_dissipation_coefficient = 0.1

Add diffusion in the z direction to suppress oscillations

Disabled by default.

The diffusion coefficient is set in the input TOML file by the parameter

[ion_numerical_dissipation]
z_dissipation_coefficient = 0.1

Note that the current distributed-memory compatible implementation does not impose a penalisation term on internal or external element boundaries

Add diffusion in the z direction to suppress oscillations for neutrals

Disabled by default.

The diffusion coefficient is set in the input TOML file by the parameter

[neutral_numerical_dissipation]
z_dissipation_coefficient = 0.1

Note that the current distributed-memory compatible implementation does not impose a penalisation term on internal or external element boundaries