Defining the Physics Models, Materials, and Boundary Conditions

As the tutorial focuses on the definition of superposed motions, you can reduce the solution time by applying simplified physics. In this simulation, you model the wing as a linear solid surrounded by a fluid in laminar regime. Assuming a laminar regime considerably reduces the computational time. However, for a more accurate FSI analysis, you would include the effect of turbulence on the flow.

The starting simulation contains two physics continua—one for the wing region, and one for the fluid and overset regions.
  1. Expand the Continua node.
  2. For the physics continuum, Fluid Physics, select the following models:
    Group Box Model
    Space Three Dimensional (already selected)
    Time Implicit Unsteady
    Material Gas
    Flow Segregated Flow
    Gradients (selected automatically)
    Overset Conservation (selected automatically)
    Equation of State Constant Density
    Viscous Regime Laminar
Specify the physics models that define the wing behavior:
  1. For the physics continuum, Solid Physics, select the following models:
    Group Box Model
    Space Three Dimensional (already selected)
    Solution Interpolation (already selected)
    Time Implicit Unsteady
    Material Solid
    Optional Models Solid Stress
    Material Law Models (selected automatically)
    Gravity

For the wing, you define a light and stiff material, which ensures that the deformations are small enough to model the wing using a linear geometry assumption.

To specify the material law models:

  1. Expand the Solid Physics > Models > Material Law Models > Material Laws node.
  2. Rename the Material Laws > Default Material Law node to Isotropic Linear Elastic.
  3. For the Isotropic Linear Elastic law node, select the following models:
    Group box Model
    Material Stiffness Models Linear Elasticity
    Material Strain Measures Linear Strain (Small Strain) (selected automatically)
    Linear Elastic Material Models Isotropic Linear Elasticity
Define the material properties:
  1. Expand the Solid Physics > Models > Solid node.
  2. Rename Al to Wing.
  3. Edit the Wing > Material Properties node and set the following properties:
    Node Property Setting
    Material Law Type Isotropic Linear Elastic (selected automatically)
    Density > Constant Value 1000.0 kg/m^3
    Young's Modulus > Constant Value 100.0 GPa
Solid stress analyses require appropriate constraints on the solid parts. In this case, you define a constraint that fixes the wing at the mount:
  1. Right-click the Regions > Wing node and select Create Segment > Surface Segment.
  2. Rename the surface segment Fixed Mount and set the following properties:
    Node Property Setting
    Fixed Mount Surfaces Wing Fixed Mount (all part surfaces)
    Type Constraint
    The default method for setting the Fixed Mount > Physics Conditions > Solid Stress Constraints is Fixed. The default setting is appropriate for this case, as it prevents displacement in any direction. When you assign a motion model to the solid region, the constraint is automatically defined with respect to the prescribed motion.
  3. Save the simulation.