Numerical study on the maneuvering of a container ship in shallow water waves

Abstract

Numerous practical and mathematical techniques have been piloted for studying the ships’ behavior in deep water conditions with and without waves, and shallow water conditions without waves, while limited investigations have only been carried out for the assessment of ships’ behavior in shallow waters with wave conditions as the flow around stern region, appendages and interaction effects are intricate. Therefore, an attempt has been made to understand the infrequently reconnoitered subset i.e. a vessel’s behavior in regular waves in shallow water condition (channel depth to ship draft ratio taken as 1.5). A container ship (S175) model of scale ratio 1:36 has been considered for numerical studies which is subjected to static and dynamic maneuver simulations in head sea condition. The waves have been induced using the dispersion relationship of waves in a given depth. The trends of forces and moments acting on the hull while undergoing maneuvering motions have been obtained using smooth particle hydrodynamics based CFD solver. The resulting periodic trends of forces and moments were analyzed using Fourier series method to extract the Fourier coefficients and in turn calculate the hydrodynamic derivatives.

The trajectories in turning circle and zig-zag maneuvers have also been simulated using a MATLAB code. This paper demonstrates an increase in trajectory parameters and improvement in counter maneuverability owing to the complex flow physics around the hull while encountering regular waves in shallow water condition when compared to those with waves in deep water and without waves in shallow waters.