flow.omega_from_viscosity
flow.omega_from_viscosity(viscosity)BGK relaxation rate for a kinematic viscosity in lattice units.
The Chapman-Enskog expansion gives nu = cs^2 (1/omega - 1/2), so a viscosity fixes the single BGK relaxation rate.
Parameters
| Name | Type | Description | Default |
|---|---|---|---|
| viscosity | float | Kinematic viscosity in lattice units (cells^2 per step). | required |
Returns
| Name | Type | Description |
|---|---|---|
| float | The relaxation rate omega, in (0, 2). |
Raises
| Name | Type | Description |
|---|---|---|
| ValueError | If the viscosity puts omega outside its stable range. |