marine hydrodynamics -- a memoir - ntnu

Marine Hydrodynamics -- a memoir

70 years anniversary seminar and celebration

for

Professor Odd M. Faltinsen and Professor Torgeir Moan

NTNU, Trondheim

19-20 May 2014

by J. N. Newman

NTNU, MIT, WAMIT Inc

Outline

• Early days of my own career (1955-1960)

• Interactions with Torgeir and Odd (1969 … )

• Computations of 3D wave effects (1980’s … )

• Closing thoughts

EST TAXES

(From CESOS Annual Report 2010 )

1955-1960 Mentors and Heroes

Martin Abkowitz, MIT

Fritz Ursell, Cambridge

Georg Weinblum, Hamburg

M. D. Haskind, Odessa

T. H. Havelock, Newcastle

John Wehausen, Berkeley

Reinier Timman, Delft

Odd’s first visit to MIT – 1971 (en-route home from Ann Arbor)

Photo: Norwegian Petroleum Museum

“The Alexander L. Kielland Accident”, by Torgeir Moan

First Wallace Lecture, MIT, June 1981

Stavanger, June 1982

Sailing in Woods Hole – September 1980 (Visiting Professor, MIT 1980-81)

Welcome to Trondheim -- August 1981

Development of 3D panel codes

Original work by Hess & Smith, JSR 1964 (no waves)

Evolution of radiation/diffraction codes

• Submerged bodies: Halkyard/Milgram (1971)

• Floating bodies: Garrison, Hogben/Standing, v.Oertmerssen, Faltinsen/Michelsen

• Alternative methods (FEM): Bai, EatockTaylor/Wu, Yue/Chen/Mei/Aranha

• Special challenge in 1980’s: TLPs

ISSC TLP comparisons from `Variability of hydrodynamic load predictions for a

tension leg platform’, Eatock Taylor and Jefferies (1986)

ISSC TLP represented by 4048 panels

(OMAE, 1988)

`My’ Computers

Year1950 1960 1970 1980 1990 2000 2010

10-2

10-1

100

101

102

103

104

105

CPU, MHz

RAM, Mbytes

IBM 704

IBM 7090

IBM PC

PC/AT

PC(8 core)

Cray

PC(1 core)

MAINFRAMES

Personal Computers(PC)

`Cloaking’ a circular cylinder in deep water Surrounding structures optimized to minimize scattered energy at

Kd=1 (wavelength = 2𝜋 × draft)

Array of 64 circular cylinders

E/E0 = 2 x 10-8

Ring with varying radius and depth

E/E0 = 5 x 10-9

y

x

y

x

Semi-sub 60 x 60 x 20 m Rings optimized to minimize the drift force

at 8 periods 6(0.5)9.5 sec

Comparison of drift forces black: no rings red: with rings

Period (sec)

DF

x

6 8 10 12

2

4

6

8

10

12

14

semi

semi + rings

More challenging problems

• Forward velocity (ships in waves)

• Nonlinear (steep / breaking waves)

• Viscous effects including separation

Extensive software is now available `off the shelf’

Great assets for offshore engineers and

naval architects,

but also a challenge to use intelligently

Good teaching and good students are vital!

marine hydrodynamics -- a memoir - ntnu

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