37. Use of RigidBody Probes

The identification tag for this tutorial is PDS-ABA. Pregenerated input files for this tutorial are found in the folder named PDS-ABA in the provided tutorial input files.

37.1. Tutorial overview

This tutorial covers:

  • DObject probes
  • Probe data files in the results folder

37.2. Using probes to output DObject data

Note

  • Probes can be used to report information about a specified DObject. For RigidBody DObjects the following probes can be used: $ArcPointProbe, $AirGapProbe, $BodyAccelProbe, $GlobalAccelProbe, and $PositionProbe.
  • $ArcPointProbe can be used to report the 3D Cartesian location of the point along the cable at the arc length specified.
  • $AirGapProbe can be used to report the air gap and relative velocity between the point specified in the body coordinate frame and the water surface.
  • $BodyAccelProbe and $GlobalAccelProbe can be used to report the accelerations of the point specified in either the body coordinate frame or the global coordinate frame.
  • $PositionProbe can be used to report the position of the point specified in the global coordinate frame.
  • Similar to the environmental probes, all DObject probes have files written to the DObject subfolder within the results subfolder.
  • In PST, create a RigidBody DObject.
  • Create a cylinder feature with a length of 10 m and a diameter of 5 m coincident with the rigid body frame.
  • Set the initial position of the RigidBody to (3,3,-5) m with a roll of 45 degrees.
  • Add the property $AirGapProbe with the location (0,0,-5) m and $BodyAccelProbe with the location (0,0,2) m to the RigidBody DObject input file.
  • Run the simulation.
  • Navigate to the DObject subfolder within the results subfolder and view the probe results.

Note

  • Notice the air gap and acceleration data reported.
  • RigidBody probes are useful for determining the acceleration and position of points of interest within an advanced RigidBody structure (multiple rigid body features). The acceleration at the body coordinate frame origin is always reported in the results.dat output file, however, points of interest such as rotor tips for turbines or the deck of a large vessel would benefit from the use of probes.