scholarly journals Analysis on Rolling Damping of a Conventional Boat fitted with T-shaped Bilge Keels

2018 ◽  
Vol 202 ◽  
pp. 02007
Author(s):  
Yam Ke San ◽  
Gordon Chiew ◽  
Chin Howe ◽  
Vincent Chieng Chen Lee ◽  
Sukanta Roy
Keyword(s):  
Fluid Dynamics ◽  
Aspect Ratio ◽  
Numerical Study ◽  
Large Aspect Ratio ◽  
Roll Damping ◽  
Damping Characteristics ◽  
Grid Approach ◽  
The Impact ◽  
Bilge Keel ◽  
Dynamics Method

This work presents a numerical study on the effect of T-shaped bilge keels on the roll damping of a conventional boat. A scaled boat model with the same dimensions as that of Irkal et al. [2] was fitted with two T-shaped bilge keels at the edges of the model. Computational Fluid Dynamics method was employed to simulate the roll decay motion of the boat. The motion of the boat is captured using a 6DOF model and the Overset grid approach. Comparison was performed on the damping characteristics of the conventional I-shaped and the T-shaped bilge keels. In addition, the impact of the aspect ratio of the keel bilges on the roll damping of the boat was evaluated. It was found that the bilge keel aspect ratio influences the damping coefficient non-linearly. Sufficiently large aspect ratio, i.e. an aspect ratio greater than 2, is necessary in order to obtain an effective damping on the peak angle.

CFD Simulation of Roll Damping Characteristics of a Ship Mid-Section With Bilge Keel

2016 ◽  
Author(s):  
Mohsin A. R. Irkal ◽  
S. Nallayarasu ◽  
S. K. Bhattacharyya
Keyword(s):  
Fluid Dynamics ◽  
Cfd Simulation ◽  
Experimental Studies ◽  
Ship Hull ◽  
Estimation Methods ◽  
Accurate Estimation ◽  
Roll Motion ◽  
Roll Damping ◽  
Damping Characteristics ◽  
Bilge Keel

The prediction of nonlinear roll motion of ships depends highly on the accurate estimation of roll damping. The nonlinear nature of roll damping arises from the viscous flow and the associated phenomenon of flow separation around the ship hull. Roll damping changes noticeably with a slight change in the ship hull geometry and appendages. The estimation methods employed in industry are highly empirical in nature. These empirical methods were derived from combinations of model tests conducted in wave flumes and basins, and some selected formulae used in fluid dynamics. These methods have limitations and the roll damping prediction show large variation with change in the ship parameters. The advances made in Computational Fluid Dynamics (CFD) in recent times, and validation of the CFD results using experimental studies, can help in predicting roll motion and damping more accurately. The present work uses CFD as a tool to estimate roll damping of a ship mid-section with bilge keel with validation using published experimental results.

Effect of Bilge Radius and Bilge Keel Height on Roll Damping Performance of Floating Structures

2021 ◽  
Author(s):  
Chang Seop Kwon ◽  
Joo-Sung Kim ◽  
Hyun Joe Kim
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Kinetic Energy ◽  
Floating Body ◽  
Rectangular Section ◽  
Roll Damping ◽  
Floating Structures ◽  
Free Decay ◽  
Computational Fluid Dynamics Cfd ◽  
Bilge Keel

Abstract A round bilge with a bilge keel structure is a key element which can alleviate roll motions of ships and floating structures by transferring the roll momentum of a floating body into the kinetic energy of water. This study presents a practical guide to properly designing a bilge radius and bilge keel height of a barge-shaped and tanker-shaped FPSOs. A parametric study to figure out the effect of bilge radius and bilge keel height on the roll damping performance is conducted through a series of numerical roll free decay simulations based on Computational Fluid Dynamics (CFD). The bilge radius is normalized by the half breadth of ship, and the bilge keel height is normalized by the maximum bilge keel height which is limited by the molded lines of a side shell and bottom shell. In addition, it is investigated to identify how the roll damping performance of a rectangular section differs from the result of a typical round bilge section with maximum available bilge keel height.

A Numerical Study of the Flow and Pollutant Dispersion in Valley-River Urban

2013 ◽  
Vol 645 ◽  
pp. 208-216
Author(s):  
Rong Huang ◽  
Naiang Wang
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Flow Field ◽  
Numerical Study ◽  
Concentration Field ◽  
Pollutant Dispersion ◽  
Northwest China ◽  
Navier Stokes ◽  
The Impact ◽  
Valley City

Air flow and pollutant dispersion characteristics in a real valley city are studied under the real boundary condition. The 3D computational fluid dynamics using Reynolds-averaged Navier-Stokes modeling was carried out in Lanzhou which is a typical valley city in Northwest, China. The standard κ­-ε turbulence model as a simplified computational fluid dynamics model is used to provide moderately fast simulations of turbulent airflow in an urban environment. The modeled flow field indicated that the geometry, wind direction and source location had a significant effects on the flow field. The flow shows the funnelling is rather obvious when the wind flow through the narrow area in the middle of the city. It is obvious that in the high-altitude region, due to the impact of high and low differential pressure and terrain, SO2 and NO2 formed two cyclic concentration field in the dispersion process.

scholarly journals Reducing drag on a flat plate subjected to incompressible laminar flow

2019 ◽  
Vol 286 ◽  
pp. 07006
Author(s):  
A. Agriss ◽  
M. Agouzoul ◽  
A. Ettaouil
Keyword(s):  
Fluid Dynamics ◽  
Flat Plate ◽  
Numerical Study ◽  
Reynolds Numbers ◽  
Ansys Fluent ◽  
Low Reynolds Numbers ◽  
Computational Fluid Dynamics Cfd ◽  
Corrugated Plates ◽  
The Impact ◽  
Reference Plate

The idea behind this work comes from the question: What is the impact of plate corrugations on drag? In this context, a numerical study of laminar incompressible flow over a flat plate and over corrugated plates is carried out. Numerical analysis is performed for low Reynolds numbers (Re= 10, Re = 50, Re = 100, Re = 500, Re =1000) using the computational fluid dynamics (CFD) software ANSYS FLUENT. Simulations results are compared to each others and with those of the reference plate (flat plate (figure 4a)). Comparisons are made via drag coefficient Cd. This work is the beginning of a study that evaluates the impact of corrugations on drag reduction on a flat plate.

Numerical study of unsteady fluid flow through a tightly coiled rectangular duct of large aspect ratio

2021 ◽  
Author(s):  
Shamsun Naher Dolon ◽  
Mohammad Sanjeed Hasan ◽  
Ratan Kumar Chanda ◽  
Rabindra Nath Mondal
Keyword(s):  
Fluid Flow ◽  
Aspect Ratio ◽  
Numerical Study ◽  
Large Aspect Ratio ◽  
Rectangular Duct ◽  
Unsteady Fluid Flow ◽  
Flow Through ◽  
Unsteady Fluid

scholarly journals A Numerical Study of the Impact of Radial Baffles in Solid Bowl Centrifuges Using Computational Fluid Dynamics

2010 ◽  
Vol 2010 ◽  
pp. 1-10 ◽  
Author(s):  
Xiana Romaní Fernández ◽  
Hermann Nirschl
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Multiphase Flow ◽  
Fine Particles ◽  
Numerical Study ◽  
Small Particles ◽  
Sedimentation Behavior ◽  
Computational Fluid Dynamics Cfd ◽  
Separation Equipment ◽  
The Impact

Centrifugal separation equipment, such as solid bowl centrifuges, is used to carry out an effective separation of fine particles from industrial fluids. Knowledge of the streams and sedimentation behavior inside solid bowl centrifuges is necessary to determine the geometry and the process parameters that lead to an optimal performance. Regarding a given industrial centrifuge geometry, a grid was built to calculate numerically the multiphase flow of water, air, and particles with a computational fluid dynamics (CFD) software. The effect of internal radial baffles on the multiphase flow was investigated. The results show that the baffles are helpful for the acceleration of the fluid, but they disturb the axial boundary layer, making it irregular, and originate a secondary circulating flow which hinders the sedimentation of small particles.

A Technological Effect Modeling on Complex Turbomachinery Applications With an Overset Grid Numerical Method

2014 ◽  
Vol 136 (10) ◽  
Author(s):  
Lionel Castillon ◽  
Gilles Billonnet ◽  
Jacques Riou ◽  
Stéphanie Péron ◽  
Christophe Benoit
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Numerical Simulations ◽  
Tip Clearance ◽  
Overset Grid ◽  
Grid Approach ◽  
Computational Fluid Dynamics Cfd ◽  
Geometrical Effects ◽  
The Impact ◽  
Casing Treatments

This paper presents an overview of numerical simulations performed at ONERA on turbomachinery configurations which include technological effects, such as tip clearance, hub disk leakage, circumferential and noncircumferential casing treatments (CTs), blade fillets, and cooling holes. An overset grid approach (Chimera technique) is used to simulate these geometrical effects with ONERA's structured computational fluid dynamics (CFD) solver elsA. Calculations performed on the different configurations enable to quantify the impact of these technological effects on the flow solution.

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