2D CRM

This script details the setup and execution of a steady-state Reynolds-Averaged Navier-Stokes (RANS) simulation for the NASA CRM-HL 2D multi-element airfoil configuration using the Flow360 Python API. It covers geometry import and preparation, automated mesh generation with multiple refinement zones, definition of simulation parameters using the SI unit system, configuration of the Spalart-Allmaras turbulence model, and submission of the simulation case.

import flow360 as fl
from flow360.examples import Tutorial2DCRM

Tutorial2DCRM.get_files()

project = fl.Project.from_geometry(Tutorial2DCRM.geometry, name="Tutorial 2D CRM from Python")
geometry = project.geometry

# show face and edge groupings
geometry.show_available_groupings(verbose_mode=True)
geometry.group_faces_by_tag("faceName")
geometry.group_edges_by_tag("edgeName")


with fl.SI_unit_system:
    cylinders = [
        fl.Cylinder(
            name=f"cylinder{i+1}",
            axis=[0, 1, 0],
            center=[0.7, 0.5, 0],
            outer_radius=outer_radius,
            height=1.0,
        )
        for i, outer_radius in enumerate([1.1, 2.2, 3.3, 4.5])
    ]
    cylinder5 = fl.Cylinder(
        name="cylinder5", axis=[-1, 0, 0], center=[6.5, 0.5, 0], outer_radius=6.5, height=10
    )
    farfield = fl.AutomatedFarfield(method="quasi-3d")
    params = fl.SimulationParams(
        meshing=fl.MeshingParams(
            defaults=fl.MeshingDefaults(
                surface_edge_growth_rate=1.17,
                surface_max_edge_length=1.1,
                curvature_resolution_angle=12 * fl.u.deg,
                boundary_layer_growth_rate=1.17,
                boundary_layer_first_layer_thickness=1.8487111e-06,
            ),
            refinement_factor=1.35,
            gap_treatment_strength=0.5,
            volume_zones=[farfield],
            refinements=[
                fl.UniformRefinement(name="refinement1", spacing=0.1, entities=[cylinders[0]]),
                fl.UniformRefinement(name="refinement2", spacing=0.15, entities=[cylinders[1]]),
                fl.UniformRefinement(name="refinement3", spacing=0.225, entities=[cylinders[2]]),
                fl.UniformRefinement(name="refinement4", spacing=0.275, entities=[cylinders[3]]),
                fl.UniformRefinement(name="refinement5", spacing=0.325, entities=[cylinder5]),
                fl.SurfaceRefinement(name="wing", max_edge_length=0.74, faces=[geometry["wing"]]),
                fl.SurfaceRefinement(
                    name="flap-slat",
                    max_edge_length=0.55,
                    faces=[geometry["flap"], geometry["slat"]],
                ),
                fl.SurfaceRefinement(
                    name="trailing",
                    max_edge_length=0.36,
                    faces=[
                        geometry["*Trailing"],
                    ],
                ),
                fl.SurfaceEdgeRefinement(
                    name="edges",
                    method=fl.HeightBasedRefinement(value=0.0007),
                    edges=[
                        geometry["*trailingEdge"],
                        geometry["*leadingEdge"],
                    ],
                ),
                fl.SurfaceEdgeRefinement(
                    name="symmetry", method=fl.ProjectAnisoSpacing(), edges=[geometry["symmetry"]]
                ),
            ],
        ),
        reference_geometry=fl.ReferenceGeometry(
            moment_center=[0.25, 0, 0], moment_length=[1, 1, 1], area=0.01
        ),
        operating_condition=fl.operating_condition_from_mach_reynolds(
            mach=0.2,
            reynolds=5e6,
            project_length_unit=1 * fl.u.m,
            temperature=272.1,
            alpha=16 * fl.u.deg,
            beta=0 * fl.u.deg,
        ),
        time_stepping=fl.Steady(
            max_steps=3000, CFL=fl.RampCFL(initial=20, final=300, ramp_steps=500)
        ),
        models=[
            fl.Wall(
                surfaces=[
                    geometry["*"],
                ],
            ),
            fl.Freestream(surfaces=farfield.farfield),
            fl.SlipWall(surfaces=farfield.symmetry_planes),
            fl.Fluid(
                navier_stokes_solver=fl.NavierStokesSolver(
                    absolute_tolerance=1e-11,
                    linear_solver=fl.LinearSolver(max_iterations=35),
                    kappa_MUSCL=0.33,
                ),
                turbulence_model_solver=fl.SpalartAllmaras(
                    absolute_tolerance=1e-10,
                    linear_solver=fl.LinearSolver(max_iterations=25),
                    equation_evaluation_frequency=1,
                ),
            ),
        ],
        outputs=[
            fl.VolumeOutput(
                output_fields=[
                    "primitiveVars",
                    "vorticity",
                    "residualNavierStokes",
                    "residualTurbulence",
                    "Cp",
                    "Mach",
                    "qcriterion",
                    "mut",
                ],
            ),
            fl.SurfaceOutput(
                surfaces=geometry["*"],
                output_fields=["primitiveVars", "Cp", "Cf", "CfVec", "yPlus"],
            ),
        ],
    )


project.run_case(params=params, name="Case of tutorial 2D CRM from Python")

Notes

• fl.AutomatedFarfield with method="quasi-3d" is employed to generate farfield and symmetry boundary conditions suitable for this 2D configuration.

• Multiple mesh refinement strategies (fl.UniformRefinement, fl.SurfaceRefinement, fl.SurfaceEdgeRefinement) are used to control grid resolution near the airfoil surfaces and in the wake.

• The simulation utilizes the Spalart-Allmaras turbulence model (fl.SpalartAllmaras).