Seakeeping and Added Resistance of IACC Yachts by a Three-Dimensional Panel Method

1993 ◽  
Author(s):  
P. D. Sclavounos ◽  
D. E. Nakos
Keyword(s):  
Sensitivity Analysis ◽  
Potential Flow ◽  
Three Dimensional ◽  
Panel Method ◽  
Radius Of Gyration ◽  
Experimental Measurements ◽  
Shape Parameters ◽  
Added Resistance ◽  
Pitch Motion ◽  
America’S Cup

A three-dimensional panel method developed for the prediction of the seakeeping properties of conventional ships has been extended to predict the motions and added resistance of IACC Yachts. The method solves the three dimensional unsteady potential flow around the yacht in monochromatic oblique waves. Predicted quantities include the heave and pitch motion amplitudes and phases and added resistance over a broad range of wave frequencies yacht speeds. Computations have been carried out for a series of IACC hull shapes studied by PACT (Partnership for America's Cup Technology) and correlations with experimental measurements are found to be very satisfactory. The same method was also used to study the added-resistance properties of hull shapes supplied by the America3 Foundation. A sensitivity analysis was carried out of the added resistance on the principal yacht hull shape parameters, including the slenderness, displacement, LCB­LCF separation and pitch radius of gyration.

Model Tests of the PACT Base America's Cup Hull in Following Seas

1997 ◽  
Author(s):  
Jesse Falsone
Keyword(s):  
Degrees Of Freedom ◽  
Model Tests ◽  
Response Amplitude ◽  
Scale Model ◽  
Radius Of Gyration ◽  
Added Resistance ◽  
Following Seas ◽  
America’S Cup ◽  
Wave Slope ◽  
Response Amplitude Operators

Model tests were conducted at the Davidson Laboratory to investigate the effect of following seas on the added resistance of the PACT (Partnership for America's Cup Technology) base America's Cup hull. A 1 :8 scale model of an International America's Cup Class yacht was provided by Team Dennis Conner and was refinished with funding from US Sailing to its original lines as the PACT base hull. Using this hull (canoe body with no appendages), model tests were conducted in the following seas condition. Upright, resistance tests were carried out at constant speed in both smooth water and regular waves of varying length and slope. The model was free to heave and pitch while restraining all other degrees of freedom. The data analysis revealed that at wavelengths approximately greater than two model lengths, the added resistance of the model is negative. A negative added resistance implies that the average drag force of the model in a particular following sea is less than the still-water drag of the model at the same speed. At wavelengths below this point, the added resistance of the model is greater than the still-water resistance. Furthermore, the form of the data suggests that at waves longer than were tested in this experiment (wavelengths greater than five model lengths), the added resistance of the model converges to the still­water resistance. The experiment also verifies that the added resistance is proportional to the square of the wave height. The pitch and heave characteristics of the model as expressed in the form of response amplitude operators are independent of wave slope. This is to say that for a particular motion, the response amplitude operators for each wave slope overlap one another. The results of these model tests were to be used as a database for the IMS Pitching Moment Project established in an attempt to quantify the sensitivity of radius of gyration on yacht performance. Also, these results were to be used to validate CFD estimates of added resistance.

scholarly journals Three-dimensional analysis of potential flow in a centrifugal impeller by panel method.

1986 ◽  
Vol 52 (484) ◽  
pp. 3993-4000
Author(s):  
Yutaka MIYAKE ◽  
Kiyoshi BANDOH ◽  
Yoshio MASUDA ◽  
Shigetaka NAGAMATSU
Keyword(s):  
Dimensional Analysis ◽  
Potential Flow ◽  
Three Dimensional ◽  
Panel Method ◽  
Centrifugal Impeller

scholarly journals Aspects of the Application of a Three Dimensional Panel Method Tool in the Design of a Light Aircraft

2005 ◽  
Author(s):  
Paulo Henriques Iscold Andrade De Oliveira ◽  
Marcos Vinícius Bortolus
Keyword(s):  
Three Dimensional ◽  
Panel Method

Upstream motions in stratified flow

1988 ◽  
Vol 187 ◽  
pp. 487-506 ◽  
Author(s):  
I. P. Castro ◽  
W. H. Snyder
Keyword(s):  
Body Height ◽  
Three Dimensional ◽  
Time Dependent ◽  
Experimental Measurements ◽  
Two Dimensional ◽  
Towing Tank ◽  
First Order ◽  
Density Perturbations ◽  
Small Obstacle ◽  
Obstacle Height

In this paper experimental measurements of the time-dependent velocity and density perturbations upstream of obstacles towed through linearly stratified fluid are presented. Attention is concentrated on two-dimensional obstacles which generate turbulent separated wakes at Froude numbers, based on velocity and body height, of less than 0.5. The form of the upstream columnar modes is shown to be largely that of first-order unattenuating disturbances, which have little resemblance to the perturbations described by small-obstacle-height theories. For two-dimensional obstacles the disturbances are similar to those found by Wei, Kao & Pao (1975) and it is shown that provided a suitable obstacle drag coefficient is specified, the lowest-order modes (at least) are quantitatively consistent with the results of the Oseen inviscid model.Discussion of some results of similar measurements upstream of three-dimensional obstacles, the importance of towing tank endwalls and the relevance of the Foster & Saffman (1970) theory for the limit of zero Froude number is also included.

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