Navier-Stokes Computation of Pitch-Damping Coefficients Using Steady Coning Motions

2004 ◽  
Vol 41 (5) ◽  
pp. 754-761 ◽  
Author(s):  
Soo Hyung Park ◽  
Jang Hyuk Kwon
AIAA Journal ◽  
1968 ◽  
Vol 6 (1) ◽  
pp. 164-165
Author(s):  
EDWARD F. BLICK

1997 ◽  
Author(s):  
N. Qin ◽  
D. Ludlow ◽  
S. Shaw ◽  
J. Edwards ◽  
A. Dupuis ◽  
...  

1987 ◽  
Vol 109 (3) ◽  
pp. 283-288 ◽  
Author(s):  
R. Chilukuri

Added mass and fluid damping coefficients for vibrations of an inner cylinder that is enclosed by a concentric outer cylinder are determined by finite element analysis of the unsteady, laminar, incompressible flow in the annulus. Continuously deforming space-time finite elements are used to track the moving cylinder and the changing shape of the space domain. For small cylinder vibration amplitudes, the present results agree well with the work of earlier investigators who solved the linearized Navier-Stokes equations on a fixed mesh. Fluid damping coefficients are shown to increase with vibration amplitude. Added mass coefficients may either increase or decrease with increasing vibration amplitude.


2005 ◽  
Vol 42 (5) ◽  
pp. 865-872 ◽  
Author(s):  
Paul Weinacht ◽  
James E. Danberg

Author(s):  
Helge Rathje ◽  
Ole Hympendahl ◽  
Jan Kaufmann ◽  
Thomas E. Schellin

New minimum intact stability criteria are presented to ensure safety against capsizing invoked by sudden loss of crane load during heavy lifts at sea, followed by typical sample stability assessments for a lifting operation on four multipurpose ships. For added stability, two of these ships had a pontoon attached at their sides opposite the lift. Two numerical time-domain methods assessed the transient dynamic heel after a sudden loss of crane load. With the ship at equilibrium, both analyses started by releasing the crane load, simulating a sudden failure of the lifting gear. The first method solved the roll motion equation as a one-degree-of-freedom system; the second method used a Reynolds-averaged Navier-Stokes equations solver. The first method relied on appropriately chosen linearized roll damping coefficients, and the nonlinearity of the righting moment function had to be accounted for. The second method required creating extensive numerical grids to idealize the ship’s hull, including the counter balancing stability pontoon, rudder and bilge keels, as well as all parts of the ship’s superstructure that effect the righting moment at large heeling angles.


2017 ◽  
Vol 372 ◽  
pp. 81-90 ◽  
Author(s):  
Rodrigo C. Lisboa ◽  
Paulo R.F. Teixeira ◽  
Eric Didier

This paper describes the analysis of the propagation of regular and irregular waves in a flume by using Fluent® model, which is based on the Navier-Stokes (NS) equations and employs the finite volume method and the Volume of Fluid (VoF) technique to deal with two-phase flows (air and water). At the end of the flume, a numerical beach is used to suppress wave reflections. The methodology consists of adding a damping sink term to the momentum equation. In this study, this term is calibrated for three cases of regular incident waves (H = 1 m, T = 5, 7.5, and 12 s) by varying the linear and quadratic damping coefficients of the formulation. In general, while lower values of damping coefficients cause residuals on the free surface elevation due to wave interactions with the outlet boundary, reflection occurs on the numerical beach when higher values are used. A range of optimal damping coefficients are found considering one of them null. In one of these cases, temporal series of free surface elevation are compared with theoretical ones and very good agreement is reached. Afterwards, an irregular wave propagation, characterized by a JONSWAP spectrum, is investigated. Several gauges along the flume are evaluated and good agreement between the spectrum obtained numerically and the ones imposed at beginning of the flume is verified. This study shows the capacity of NS models, such as Fluent®, to simulate adequately regular and irregular wave propagations in a flume with numerical beach to avoid reflections.


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