Large eddy simulations of flow around underwater gliders and the impact on sensor measurements

Numerical studies of the flow over an underwater glider was simulated to investigate; 1) the extent to which the measurements of sensors (including turbulence sensors) on an AUV are affected by the distortion of the flow around the vehicle body, 2) the occurrence of bioluminescence in the wakes of autonomous vehicles, and 3) the quantification of the hydrodynamic forces on AUV’s. Two example simulations were conducted. In both cases the flow around a Slocum Mk II glider was simulated and the second example included a MicroRider turbulence package mounted on top of the glider. Our preliminary results suggest that the usual position of the oxygen sensor on a Slocum glider may be within a separated wake that could significantly affect the data quality. Flow distortion at the location of the shear probes on the turbulence package is low but could result in a small underestimation of the magnitude of dissipation. We also find that the shear stress on the wing edges of a glider could be sufficient to stimulate bioluminescence in certain environments but is at the lower end the range at which bioluminescence occurs. Lift and drag forces diagnosed from the simulations were consistent with data from gliders but a more detailed study is needed to assess the quantitative accuracy of these results