Apply Boundary Conditions

Apply boundary conditions, such as flow conditions and symmetry, to the fluid domain.

Applying boundary conditions to a fluid domain defines how the fluid flows through or around the model. Common types of boundary conditions include hydrostatic pressure, free streams, intake or exhaust fans, inlet velocities, and outlet pressures.

In this example, the air flows around the nose of the drone toward its tail. You apply velocity and pressure conditions on the bounding box to prescribe the direction and speed of the airflow around the drone. Then, you define symmetry and wall boundary conditions to more realistically represent the behavior of the airflow at the surfaces of the bounding box.

  1. From the Boundaries section of the Assistant, click Velocity Inlet .
  2. Select the outer side of the bounding box (that is, the blue rectangular glyph) that is in front of the drone's nose as the support.

    Tip: You can also expand Model > Drone A.1 > Airflow Mesh A.1 > Abstractions > Physical Environment.1 > Bounding Box.1 in the tree, and select Bounding box face.6.

    A set of orange arrows appears in the 3D area. These arrows, which represent the direction of airflow, point toward the drone's nose.
  3. Enter 22.352m_s in the Velocity field, and click OK.
  4. From the Boundaries section of the Assistant, click Pressure Outlet .
  5. Select the outer side of the bounding box that is behind the drone's tail as the support, and click OK.

    0 N/m2 static gauge pressure is representative of atmospheric pressure, which is a typical flight condition for this drone's missions.

    A second set of arrows, which represent the pressure, appears in the 3D area, as shown below.

  6. From the Boundaries section of the Assistant, click Symmetry .
  7. Select the side of the bounding box that divides the drone into symmetrical halves, and click OK.
    A semitransparent cuboid, which represents the symmetry condition, appears on the selected face of the bounding box.
  8. From the Boundaries section of the Assistant, click Wall .
  9. Select the top, bottom, and side of the bounding box as the support, as shown below.
  10. From the Wall type options, select Slip.

    A slip wall type prevents fluid from sticking to the selected surface. Since the drone is in an open environment, a boundary layer at any of the bounding box's surfaces is undesirable.