Effect of amplitudes and frequencies on Virtual Planar Motion Mechanism of AUVs, Part I: Forces, moments and hydrodynamic derivatives

Abstract

Planar motion mechanism tests have been widely used in the virtual form for ocean craft, especially for underwater vehicles. These tests involve a pre-determined sinusoidal trajectory for the AUV. While there are general guidelines for the choice of amplitude and frequency for such trajectories in existing literature, there are minimal to none for smaller submerged ocean craft such as autonomous underwater vehicles. This series of articles analyzes VPMM from the perspective of AUVs and the significance of variation in these parameters. The results in Part I of this series are discussed in terms of forces and moments reconstructed using hydrodynamic derivatives obtained through RANSE. This includes variation in forces and moments, and the possible non-linear effects that cause such variation. The resultant hydrodynamic damping derivatives show upto 50% variation based on parameters that signify pure sway and pure yaw simulations. The resultant added mass derivatives do not vary much among the various VPMM simulations attempted (<2%). The inflow angle to the craft is found to be significant in characterizing pure sway simulations.The results in Part II are discussed in terms of implemented dynamic maneuvers through RANSE and in field.