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TECHNICAL PAPERS

# Numerical Analysis of Unsteady Viscous Flow Through a Weis-Fogh-Type Ship Propulsion Mechanism Using the Advanced Vortex Method

[+] Author and Article Information
Kideok Ro1

School of Mechanical and Aerospace Institute of Marine Industry, Gyeongsang National University, Korearokid@gaechuk.gsnu.ac.kr

Baoshan Zhu

Department of Thermal Engineering, Tsinghua University, China

Hokeun Kang

School of Mechanical and Aerospace Institute of Marine Industry, Gyeongsang National University, Korea

1

Corresponding author.

J. Fluids Eng 128(3), 481-487 (Dec 12, 2005) (7 pages) doi:10.1115/1.2174059 History: Received January 05, 2005; Revised December 12, 2005

## Abstract

The velocity and pressure field of a ship’s Weis-Fogh-type propulsion mechanism are studied in this paper using an advanced vortex method. The wing (NACA0010 airfoil) and channel are approximated by source and vortex panels, and free vortices are introduced away from the body surfaces. The viscous diffusion of fluid is represented using the core-spreading model to the discrete vortices. The velocity is calculated on the basis of the generalized Biot-Savart law and the pressure field is calculated from an integral, based on the instantaneous velocity and vorticity distributions in the flow field. Two-dimensional unsteady viscous flow calculations of this propulsion mechanism are shown, and the calculated results agree qualitatively with the measured thrust and drag due to unmodeled large fluctuations in the measured data.

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## Figures

Figure 12

Time variations for thrust coefficients

Figure 13

Time variations for drag coefficients

Figure 5

Surface vorticity distribution for different number of panels and time step size: Re=3000, t=5.0

Figure 4

Comparison of streamlines for Re=3000 at t=5.0, (a) present method, panel number 80, dt=0.02; (b) present method, panel number 160, dt=0.01; (c) flow visualization by Bouard and Coutanceau (9)

Figure 3

Flow field involving vorticity region

Figure 2

Thin vorticity layer and nascent vortex element

Figure 1

A model of propulsion mechanism

Figure 6

Surface pressure distribution for different number of panels and time step size: Re=3000, t=5.0

Figure 7

Time variations in lift and drag coefficients: Re=1000

Figure 8

Streak lines for one stroke of the wing (C=1, h=2.5C, V∕U=1.0, rp=0.75C, and α=30deg)

Figure 9

Flow pattern for one stroke of the wing

Figure 10

Various flowfields at the point 3 of Fig. 8

Figure 11

Pressure distribution around the wing ((a), (b), and (c) in the figure correspond to 1, 3, and 5 points in Fig. 8)

## Errata

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