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Ocean Engineering

# Mitigation of Vortex-Induced Motion (VIM) on a Monocolumn Platform: Forces and Movements

[+] Author and Article Information
Rodolfo T. Gonçalves

TPN–Numerical Offshore Tank, Department of Naval Architecture and Ocean Engineering, Escola Politécnica, University of São Paulo, Avenue Professor Mello Moraes, 2231, Cidade Universitária, São Paulo, SP, 05508-900, Brazilrodolfo_tg@tpn.usp.br

André L. C. Fujarra

TPN–Numerical Offshore Tank, Department of Naval Architecture and Ocean Engineering, Escola Politécnica, University of São Paulo, Avenue Professor Mello Moraes, 2231, Cidade Universitária, São Paulo, SP, 05508-900, Brazilafujarra@usp.br

Guilherme F. Rosetti

TPN–Numerical Offshore Tank, Department of Naval Architecture and Ocean Engineering, Escola Politécnica, University of São Paulo, Avenue Professor Mello Moraes, 2231, Cidade Universitária, São Paulo, SP, 05508-900, Brazilguilherme.feitosa@tpn.usp.br

Kazuo Nishimoto

TPN–Numerical Offshore Tank, Department of Naval Architecture and Ocean Engineering, Escola Politécnica, University of São Paulo, Avenue Professor Mello Moraes, 2231, Cidade Universitária, São Paulo, SP, 05508-900, Brazilknishimo@usp.br

J. Offshore Mech. Arct. Eng 132(4), 041102 (Sep 24, 2010) (16 pages) doi:10.1115/1.4001440 History: Received September 22, 2009; Revised February 03, 2010; Published September 24, 2010; Online September 24, 2010

## Abstract

A great deal of works has been developed on the spar vortex-induced motion (VIM) issue. There are, however, very few published works concerning VIM of monocolumn platforms, partly due to the fact that the concept is fairly recent and the first unit was only installed last year. In this context, a meticulous study on VIM for this type of platform concept is presented here. Model test experiments were performed to check the influence of many factors on VIM, such as different headings, wave/current coexistence, different drafts, suppression elements, and the presence of risers. The results of the experiments presented here are motion amplitudes in both in-line and transverse directions, forces and added-mass coefficients, ratios of actual oscillation and natural periods, and motions in the $XY$ plane. This is, therefore, a very extensive and important data set for comparisons and validations of theoretical and numerical models for VIM prediction.

Copyright © 2010 by American Society of Mechanical Engineers
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## Figures

Figure 1

Sketch of the main dimensions of the unit

Figure 2

Plot presents the range of Reynolds numbers that were tested

Figure 3

Roughness of the model in detail (k/D=4×10−3)

Figure 4

Picture of the model made with polyvinyl chloride (PVC)

Figure 5

Sketch of the equivalent mooring system composed of four lines

Figure 6

Variation of the nondimensional amplitudes as a function of the reduced velocities for the 0-deg incidence

Figure 7

Variation of the nondimensional amplitudes as a function of the reduced velocities for the 45-deg incidence

Figure 8

Variation of the nondimensional amplitudes as a function of the reduced velocities for the 135-deg incidence

Figure 9

Variation of the nondimensional amplitudes as a function of the reduced velocities for the 180-deg incidence

Figure 10

Variation of the nondimensional amplitudes as a function of reduced velocities for the 315-deg incidence

Figure 11

Variation of the nondimensional periods as a function of the reduced velocities for the 45-deg incidence

Figure 12

Variation of the nondimensional periods as a function of the reduced velocities for the 135-deg incidence

Figure 13

Variation of the nondimensional periods as a function of the reduced velocities for the 180-deg incidence

Figure 14

Variation of the nondimensional periods as a function of the reduced velocities for the 315-deg incidence

Figure 15

Motion on the XY plane for the 0-deg incidence

Figure 16

Motion on the XY plane for the (a) 45-deg and (b) 135-deg incidences

Figure 17

Motion on the XY plane for the (a) 180-deg and (b) 315-deg incidences

Figure 18

Variation of drag coefficients as a function of reduced velocities for the 0-deg incidence

Figure 19

Variation of drag coefficients as a function of reduced velocities for the 45-deg incidence

Figure 20

Variation of drag coefficients as a function of reduced velocities for the 135-deg incidence

Figure 21

Variation of drag coefficients as a function of reduced velocities for the 180-deg incidence

Figure 22

Variation of drag coefficients as a function of reduced velocities for the 315-deg incidence

Figure 23

Variation of the lift coefficient (CL) above, and the added (Ca) below, as a function of the reduced velocity for the 0-deg incidence

Figure 24

Variation of the lift coefficient (CL) above, and the added (Ca) below, as a function of the reduced velocity for the 45-deg incidence

Figure 25

Variation of the lift coefficient (CL) above, and the added (Ca) below, as a function of the reduced velocity for the 135-deg incidence

Figure 26

Variation of the lift coefficient (CL) above, and the added (Ca) below, as a function of the reduced velocity for the 180-deg incidence

Figure 27

Variation of the lift coefficient (CL) above, and the added (Ca) below, as a function of the reduced velocity for the 315-deg incidence

Figure 28

Sketch of the distribution of the spoiler plates at the monocolumn

Figure 29

Variation in the nondimensional amplitudes as a function of the reduced velocity for the 0-deg incidence in the presence of spoiler plates

Figure 30

Variation in the nondimensional periods as a function of the reduced velocity for the 0-deg incidence in the presence of spoiler plates

Figure 31

Motions on the XY plane (in-line and cross-flow) for the 0-deg incidence; (a) with and (b) without presence of spoiler plates

Figure 32

Variation of drag coefficients as a function of reduced velocities for the 0-deg incidence in the presence of the spoiler plates

Figure 33

Variation of the lift coefficient (CL) above, and the added (Ca) below, as a function of the reduced velocity for the 0-deg incidence in the presence of the spoiler plates

Figure 34

Complementary distribution of the risers incorporated to the MonoBR, with (a) only the risers and (b) with the entire set

Figure 35

Variation of the nondimensional amplitudes as a function of the reduced velocity for the 0-deg incidence with external damping

Figure 36

Variation of the nondimensional periods as a function of the reduced velocity for the 0-deg incidence with external damping

Figure 37

Motions on the XY plane (in-line and cross-flow) for the 0-deg incidence; (a) without and (b) with the presence of external damping (risers)

Figure 38

Variation of drag coefficients as a function of reduced velocities for the 0-deg incidence with external damping

Figure 39

Variation of the lift coefficient (CL) above, and the added (Ca) below, as a function of the reduced velocity for the 0-deg incidence with external damping

Figure 40

Variation of the nondimensional amplitudes as a function of reduced velocity for the 0-deg incidence with simultaneous waves present

Figure 41

Variation of the nondimensional periods as a function of the reduced velocity for the 0-deg incidence with simultaneous waves present

Figure 42

Comparison between the heave response amplitude operator (RAO), numerically obtained and the experimental values obtained in the tests

Figure 43

Motions on the XY plane (in-line and cross-flow) for the 0-deg incidence, in three sea conditions

Figure 44

Variation of drag coefficients as a function of reduced velocities for the 0-deg incidence with simultaneous waves present

Figure 45

Variation of the lift coefficient (CL) above, and the added (Ca) below, as a function of the reduced velocity for the 0-deg incidence with simultaneous waves present

Figure 46

Variation of the nondimensional amplitudes as a function of the reduced velocity for the 0-deg incidence varying draft

Figure 47

Variation of the nondimensional periods as a function of the reduced velocity for the 0-deg incidence varying draft

Figure 48

Motions on the XY plane (in-line and cross-flow) for the 0-deg incidence; in two drafts: (a) operational and (b) light weight

Figure 49

Variation of drag coefficients as a function of reduced velocities for the 0-deg incidence varying draft

Figure 50

Variation of the lift coefficient (CL) above, and the added (Ca) below, as a function of the reduced velocity for the 0-deg incidence varying draft

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