Page 446 - Practical Design Ships and Floating Structures

Practical Design of Ships and Other Floating Structures 42 I
You-Sheng Wu, Wei-Cheng Cui and Guo-Jun Zhou (Eds)
0 200 I Elsevier Science Ltd. All rights reserved

VISCOUS FLOW AROUND ROTATING SHIPS

Carlos Levi and Juan B. Villa Wanderley

Department of Ocean Engineering, Universidade Federal do Rio de Janeiro
Rio de Janeiro - 21945-970. Brazil

ABSTRACT

The present stage of viscous flow numerical analysis combined with computer technology latest
advances made viable the mathematical treatment of robust and complex problems. Many heavy
numerical problems that solutions would be just unthinkable not more than ten years ago may be now
dealt with in a reliable and fairly accurate manner. A truly example of this kind of problem would be
the calculation of hydrodynamic loads acting on rotating ships.
This paper discusses the numerical solution of viscous flow around slowly rotating arbitrary floating
bodies in the presence of an incident flow. The solution of such a problem raises practical interest due
to applications, for instance, as in the case of FPSOESO ships used in deep water oil production
offshore.
In the present solution, the complete incompressible Navier-Stokes equations will be solved through a
Finite Difference based-solver using generalized coordinates defined on a moving grid. The
constitutive equations will be discretised in the space by second order central differences. Euler
Explicit method performs the time-marching and the Successive Over Relaxation method solves the
Poisson Equation at each iteration to calculate pressure distribution.

KEYWORDS

Viscous Flow, Rotating Ships, Finite Difference, Moving Grid

1 INTRODUCTION

Offshore oil and gas production is advancing fast towards water depth deeper and deeper. In the last
couple of years, world records have been successively superceded. Oil industry is about to achieve
production in fields approaching 2000m water depth while keeping on exploring new oil reservoirs in
regions close to 3000m deep.
As water depth increases, the distance from oil field to mainland depots increases at similar rates and
more hostile the ocean environment becomes. In such operational conditions the use of VLCC ship
tanker has been proved to be technical and economically appealing.