CFD-Based Reduced-Order Modeling for Numerical Prediction of Ships Maneuvering in Waves
Abstract
Approved for Public ReleaseThe design of naval vessels requires understanding of the ship motions and loads whileoperating in the oc,ean. This includes prediction of the ship trajectory, the oscillatory sixdegree-of-freedom motions of heave, pitch and roll etc, the, extreme motions that leadto broaching and capsize, and the resulting structural loads due to the wave action andmotion. It is diffi,cult to accurately predict motions and loads for many reasons. Shipsoperate for years and during their lifetime will experience a wi,de range of seawayconditions. The ocean waves and wind are random, and characterized by a wide rangeof wave lengths, wave amplitude,, wave heading, energy distributions, and winddirection, intensity, and turbulence. Ship motion in waves depends on the couplingbetwe,en the waves, and the forces on the hull, rudders and propellers. In many cases,especially during maneuvers in large seaways, the fl,ow around the ship can exhibitviscous separation, and there is often wave breaking near the hull and there may evenbe green water on, deck. These are but a few of the physical aspects of ship operationthat are complex and challenging to understand and incorporate i,nto design. Thecurrent tools are sufficiently lacking such that current designs are either overlyconservative (heavy and expensive),, or at risk for capsize (DDG100), or vulnerable tostructural failure that would require expensive retrofit and repair (LCS trimaran),.Recent work has been directed towards developing a new method for the prediction ofships maneuvering in waves. The new method uses,CFD and machine learningtechniques to develop a rudder and propeller model. The model is then used with abare-hull CFD simulation so, that maneuvering in waves simulations can be conductedaccurately and efficiently without the need overset grids. The current status, of themodel is to perform turning circles (single rudder angle), and preliminary results areavailable for moving rudder (course kee,ping and zig-zag).In the proposed work the rudder and propeller model will be extended to account forgeneral ship maneuvering in wav,es which includes arbitrary rudder angle throughout awide range of sea states. The model will be extended to assess the flow-fieldpr,ediction due to the modeled rudder. The work will identify the training datarequirement and procedure for a given level of model unc,ertainty.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jul 08, 2022
- Source ID
- N000142212509
Entities
People
- Kevin J. Maki
Organizations
- Board of Regents of the University of Michigan
- Office of Naval Research
- United States Navy