Modeling Rigid Body Motion in a Fluid Flow

You can simulate the effects of a rigid body moving through fluid flow. This workflow highlights all of the steps required to define rigid body motion in a flow simulation.

Simulating rigid body motion properly requires several additional steps in your simulation.

  1. Define a rigid body section for a part, positioned such that its boundary interfaces with the fluid domain. You can define multiple rigid body sections, one for each rigid body to consider. For more information, see Defining Rigid Body Section Properties.
  2. Mesh each rigid body part using a volumetric mesh. The rigid body mesh is for tracking the body and visualization purposes; therefore, it does not require a high resolution.
  3. In addition to the fluid physics, you need to create and define the solid physics and enable rigid body motion. The app automatically generates a solid interface with an automatic support type. For more information, see Defining the Solid Physics of a Flow Simulation.
  4. Create a transient flow step. For more information, see Transient Flow Steps.
  5. If desired, specify the initial velocity for the rigid body. For more information, see Defining Initial Rigid Body Velocity.
  6. Specify the force, torque, and displacement restraint for the rigid body. For more information, see Defining a Rigid Body Force, Defining a Rigid Body Torque, and Defining a Rigid Body Displacement Restraint.
  7. Specify the output requests for the simulation. The output available depends on your choice of support:
    • For the whole model or a part representing the body, you can request velocity and displacements as field output.
    • For the rigid body section, you can request history output related to the rigid body reference point, such as its translations, rotations, velocities, and angular velocities.

    For more information, see Defining Output Requests.

When the simulation results are available, you can plot the displacement and velocity field output for the rigid body. You can also create history plots of the displacement, rotational angle, velocity, and angular velocity of each body's center of gravity. The app expresses the rotation angles and angular velocities in intrinsic angles using the Tait-Bryan convention, also known as Cardan angles or nautical angles. These angles express rotation and angular velocity in terms of yaw, pitch, and roll.