Comparison of the Hydrodynamic Performance of Ten Underwater Vehicles by CFD Analysis

The present work aims to determine the efficient hydrodynamic shape of an underwater vehicle with minimal energy consumption throughcomputational fluid dynamicsanalysis.The study examines five axisymmetric bow-stern shape combinations, viz., elliptical-elliptical, spherical-conical,conical-conical, elliptical-conical, and elliptical-curved, for a cylindrical midsection with a diameter of 2.33 m.A study was conducted with two fineness ratios, 2 and 3,corresponding to midsection lengths of 2 m and 4.33 m, respectively, while keeping the bow and stern lengths constant. Ansys Fluent software is used for analysis, solving the Reynolds-averaged Navier-Stokesequations with the k-ε turbulence model. The drag coefficient, drag force, form drag, viscous resistance, lift coefficient, and lift forceare calculated for all the different combinations. Pressure contours, velocity contours, and velocity streamlines are plotted to visualize the flow characteristics. The velocity streamlines clearly reveal a wake region near the stern of the vehicle, indicating the occurrence of flow separation.Results reveal that the elliptical bow and curved sternexperience the least resistance, indicating the besthydrodynamically efficient shape among the combinations of shapes investigated.An increase in the fineness ratio leads to a decrease in both the drag coefficient and drag force of the underwater vehicle.