Turbulence models¶

Turbulence is configured with model-specific Python objects. Each object exposes only controls meaningful to that model, so invalid combinations are rejected before a job is submitted.

Enumerations¶

class gradientdynamics.fluxcore.TurbulenceModel¶

Supported turbulence-model families.

LAMINAR = laminar¶

K_OMEGA_SST = k_omega_sst¶

SPALART_ALLMARAS = spalart_allmaras¶

class gradientdynamics.fluxcore.WallTreatment¶

Near-wall modelling policy.

LOW_RE = low_re¶: Resolve the viscous sublayer. Use a mesh with appropriate first-cell height.

WALL_FUNCTION = wall_function¶: Apply a wall-modelled treatment for meshes designed around wall functions.

AUTOMATIC = automatic¶: Select a compatible treatment from mesh resolution and boundary metadata.

RANS models¶

class gradientdynamics.fluxcore.KOmegaSST(*, wall_treatment: WallTreatment | str = 'low_re', inlet_intensity: float = 0.01, inlet_viscosity_ratio: float = 10.0, production_limiter: float | None = None, turbulent_prandtl: float = 0.85, minimum_tke: float | None = None, minimum_specific_dissipation: float | None = None, scale_resolving: DES | DDES | None = None)¶

Two-equation shear-stress-transport turbulence model.

inlet_intensity: float¶: Freestream turbulence intensity as a fraction.

inlet_viscosity_ratio: float¶: Freestream turbulent-to-molecular viscosity ratio.

production_limiter: float | None¶: Optional upper limiter for turbulent production. Omit for the validated model default.

scale_resolving: DES | DDES | None¶: Optional detached-eddy formulation. Requires physical-time advancement.

class gradientdynamics.fluxcore.SpalartAllmaras(*, wall_treatment: WallTreatment | str = 'low_re', inlet_modified_viscosity_ratio: float = 3.0, formulation: str = 'standard', minimum_working_variable: float | None = None, production_limiter: float | None = None, scale_resolving: DES | DDES | None = None)¶

One-equation turbulence model with optional detached-eddy behaviour.

inlet_modified_viscosity_ratio: float¶: Freestream modified turbulent-viscosity ratio.

formulation: Literal['standard', 'negative']¶: Working-variable formulation. The negative variant permits controlled negative values during difficult startup transients.

scale_resolving: DES | DDES | None¶: Optional detached-eddy formulation. Requires physical-time advancement.

Scale-resolving modes¶

class gradientdynamics.fluxcore.DES(*, constant: float | None = None, length_scale: str = 'cell_volume', low_dissipation: bool = True, limiter_relaxation: float = 1.0)¶

Detached Eddy Simulation configuration for supported turbulence models.

constant: float | None¶: Optional model constant override. Omit to use the validated constant for the selected turbulence family.

length_scale: Literal['cell_volume', 'maximum_edge']¶: Grid length used by the scale-resolving model.

low_dissipation: bool¶: Use the time-resolved spatial policy intended to preserve resolved turbulent structures.

class gradientdynamics.fluxcore.DDES(*, constants: Mapping[str, float] | None = None, length_scale: str = 'cell_volume', shielding: str = 'automatic', shielding_strength: float = 1.0, low_dissipation: bool = True, limiter_relaxation: float = 1.0)¶

Delayed Detached Eddy Simulation configuration with near-wall shielding.

constants: Mapping[str, float] | None¶: Optional model-family constants. Unspecified entries use validated defaults.

shielding: Literal['automatic', 'standard', 'strong']¶: Near-wall shielding policy used to protect attached boundary layers from premature grid-induced mode switching.

shielding_strength: float¶: Multiplier applied to the selected shielding policy.

Important

DES and DDES require PhysicalTimeControls. FluxCore rejects these modes for a steady RANS configuration because the resolved turbulent content must evolve in physical time.

DDES example¶

from gradientdynamics.fluxcore import DDES, KOmegaSST, WallTreatment

turbulence = KOmegaSST(
    wall_treatment=WallTreatment.LOW_RE,
    inlet_intensity=0.005,
    inlet_viscosity_ratio=5.0,
    scale_resolving=DDES(
        length_scale="cell_volume",
        shielding="automatic",
        low_dissipation=True,
    ),
)