2D GA(W)-2

This document details the setup and execution of a steady-state simulation for flow over a 2D General Aviation (Whitcomb)-2 airfoil using the Flow360 Python API. The process begins with importing the geometry, followed by automated mesh generation incorporating several refinement strategies. Simulation parameters, including the operating conditions and reference geometry, are defined using the SI unit system. The Spalart-Allmaras turbulence model is employed, and specific output fields are requested before the case is submitted for execution.

import flow360 as fl
from flow360.examples import Tutorial2DGAW2

Tutorial2DGAW2.get_files()

project = fl.Project.from_geometry(Tutorial2DGAW2.geometry, name="Tutorial 2D GA(W)-2 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=1.12,
                boundary_layer_first_layer_thickness=2.8089171e-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",
                    max_edge_length=0.55,
                    faces=[geometry["flap"]],
                ),
                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=0.13,
            reynolds=2.2e06,
            project_length_unit=1 * fl.u.m,
            temperature=288.16,
            alpha=4 * 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 GA(W)-2 from Python")

Notes

• fl.AutomatedFarfield with method="quasi-3d" is used to establish the farfield boundary conditions appropriate for a 2D simulation setup.

• Multiple mesh refinement strategies are employed, including fl.UniformRefinement around cylindrical regions, and fl.SurfaceRefinement and fl.SurfaceEdgeRefinement on specific airfoil surfaces and edges to enhance mesh resolution in critical areas.

• The Spalart-Allmaras turbulence model (fl.SpalartAllmaras) is utilized for modeling turbulent flow characteristics.