Stability simulation for underwater glider parking on seabed

To investigate the stability parking of an underwater glider, a numerical simulation is carried out. Two types of instability states of the underwater glider are defined, namely, “when the fluid drag exceeds the friction between the hydraulic support and the seabed, sideslip occurs” and “when the fluid torque relatively to the fulcrum exceeds the restoring torque from net gravity, side roll occurs”. The mathematical models of the instability state are established. Considering the coupling of the underwater glider between flow field and seabed, the numerical simulation is carried out with ANSYS-CFX. Under the conditions of different flow velocities (0-2 m/s), distances (0.15-0.5 m) and attitude angles, the curves of the fluid force and torque are completed. It reveals that when the distance between the buoyant and seabed is smaller than 0.3 m, wall effect is obvious, which is helpful in the stability of the glider, and attack angle of the glider greatly reduces the stability of the whole system; when azimuth angle is at 150°-155°, the disturbance of fluid is most obvious. The results can be used for practical design and parking experiment for a new underwater glider.