Experimental investigation of hydrodynamic interaction between a squat submarine operating behind a ship

Abstract

This article experimentally investigates the hydrodynamic interaction of a squat submarine operating behind a ship in various wave and resistance tests. A 0.625 m long (one-tenth scale) captive model of a squat submarine is constructed along with a 1.5 m Fridsma ship to perform 47 unique experiments in a 4 × 6 × 400 m3 tank located in a towing tank center. The submarine is a new midget-submersible, of Apam-Napat SMSD type, with an L/D ratio below four. Wave and resistance tests are performed for various 2D relative lengths and depths at short-distance conditions. A wave of 0.1 m height and 1.5 m wavelength is used in the wave tests, and different operational velocities of 0.5, 1.0, and 1.5 m/s are used in the resistance tests. In each case, drag and heave forces are recorded and presented for the vessels using non-dimensional units. Finally, outputs are extended to develop 2D contours to estimate the interactional forces in the full domain. Results show that the interaction between surface waves creates a critical zone behind the ship around the 0.75D depth where the submarine drag forces are increased by up to 41%.