A numerical study to analyse the effects of a micro-sized antifouling topography applied on a ship’s hull with the aid of computational fluid dynamics (CFD)

2020 ◽  
Author(s):  
Wei Tao Johnson Lee ◽  
Yen Myan Felicia Wong
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Numerical Study ◽  
Computational Fluid Dynamics Cfd

scholarly journals Trim Influence on Kriso Container Ship (KCS): An Experimental and Numerical Study

2017 ◽  
Author(s):  
Emil Shivachev ◽  
Mahdi Khorasanchi ◽  
Alexander H. Day
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Numerical Study ◽  
Computational Cost ◽  
Breaking Waves ◽  
Computational Techniques ◽  
Container Ship ◽  
Towing Tank ◽  
Operational Life ◽  
Computational Fluid Dynamics Cfd

There has been a lot of interest in trim optimisation to reduce fuel consumption and emissions of ships. Many existing ships are designed for a single operational condition with the aim of producing low resistance at their design speed and draft with an even keel. Given that a ship will often sail outside this condition over its operational life and moreover some vessels such as LNG carriers return in ballast condition in one leg, the effect of trim on ships resistance will be significant. Ship trim optimization analysis has traditionally been done through towing tank testing. Computational techniques have become increasingly popular for design and optimization applications in all engineering disciplines. Computational Fluid Dynamics (CFD), is the fastest developing area in marine fluid dynamics as an alternative to model tests. High fidelity CFD methods are capable of modelling breaking waves which is especially crucial for trim optimisation studies where the bulbous bow partially emerges or the transom stern partially immerses. This paper presents a trim optimization study on the Kriso Container Ship (KCS) using computational fluid dynamics (CFD) in conjunction with towing tank tests. A series of resistance tests for various trim angles and speeds were conducted at 1:75 scale at design draft. CFD computations were carried out for the same conditions with the hull both fixed and free to sink and trim. Dynamic sinkage and trim add to the computational cost and thus slow the optimisation process. The results obtained from CFD simulations were in good agreement with the experiments. After validating the applicability of the computational model, the same mesh, boundary conditions and solution techniques were used to obtain resistance values for different trim conditions at different Froude numbers. Both the fixed and free trim/sinkage models could predict the trend of resistance with variation of trim angles; however the fixed model failed to measure the absolute values as accurately as the free model. It was concluded that a fixed CFD model, although computationally faster and cheaper, can find the optimum trim angle but cannot predict the amount of savings with very high accuracy. Results concerning the performance of the vessel at different speeds and trim angles were analysed and optimum trim is suggested.

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 Numerical Study of Flow Field in a Hydrocyclone for Potash Ore Desliming

2013 ◽  
Vol 448-453 ◽  
pp. 3847-3850
Author(s):  
Da Li ◽  
Fang Qin Cheng ◽  
Jian Feng Li ◽  
Yun Shan Guan
Keyword(s):  
Fluid Dynamics ◽  
Numerical Simulation ◽  
Computational Fluid Dynamics ◽  
Flow Field ◽  
Numerical Study ◽  
Numerical Approach ◽  
Basic Information ◽  
Feed Composition ◽  
Accurate Design ◽  
Computational Fluid Dynamics Cfd

Despite the widespread use of hydrocyclone in the process of potash ore desliming, its accurate design is often difficult because the feed composition is complicated and the viscosity is high in the brine system. In this study, a numerical approach based on computational fluid dynamics (CFD) was performed to describe the flow field. The numerical simulation of flow pattern in hydrocyclones for potash ore desliming was presented. Some basic information concerning the velocity and pressure distribution is given, and the results can be used as the fundamental basis for its design.

Numerical Study of Internal Fire Whirls in a Kitchen With Ceiling Vents

2013 ◽  
Author(s):  
W. K. Chow ◽  
N. Cai ◽  
Y. Gao
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Numerical Study ◽  
Air Flow ◽  
Ventilation System ◽  
Necessary Condition ◽  
Temperature Distributions ◽  
Computational Fluid Dynamics Cfd ◽  
Fire Whirl ◽  
Set Up

The characteristics of flame rotation induced by a fire at the top of kitchen stove were studied numerically with Computational Fluid Dynamics (CFD). Four cases with different locations of fire sources and vents were set up; simulations of swirling air flow and temperature distributions in the kitchen room were carried out. Ventilation by ceiling vents was identified as the necessary condition for internal fire whirl. Recommendations on the design of kitchen ventilation system were made.

Numerical Study of Micromixers for Stopped Flow

2011 ◽  
Author(s):  
Dominik Du¨chs ◽  
Sabine Brunklaus ◽  
Peter Spang ◽  
Marion Ritzi-Lehnert ◽  
Klaus Drese
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Potential Application ◽  
Numerical Study ◽  
Stopped Flow ◽  
Microfluidic Chips ◽  
Cfd Simulations ◽  
Mixing Parameter ◽  
Different Types ◽  
Computational Fluid Dynamics Cfd

Computational fluid dynamics (CFD) simulations are conducted to compare the efficiency of different types of micromixers with respect to their potential application in chip-based stopped-flow designs. The evaluation of a mixing parameter for different geometries and at various flow velocities enables a comparison between the Berger ball mixer and other designs that are in principle suitable for applications in microfluidic chips.

scholarly journals Computational Fluid Dynamics Study of Balloon System Tethered to a Stratosail

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Jayakanth Loganathan ◽  
Kian-Meng Lim ◽  
Heow Pueh Lee ◽  
Boo Cheong Khoo
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Drift Velocity ◽  
Numerical Study ◽  
Cfd Simulations ◽  
Wind Speeds ◽  
Drag Forces ◽  
Stratospheric Balloon ◽  
Computational Fluid Dynamics Cfd ◽  
Balloon System

In this paper, we present a numerical study of a stratospheric balloon system tethered to a passive device, known as the Stratosail, for station-keeping operation. For scientific applications, stratospheric balloons that operate at altitudes between 15 and 20 km will need to maintain station over a fixed point above the earth for a prescribed period of time. This is a challenging problem due to the limitation of payloads and lack of an energy source. The present study uses computational fluid dynamics (CFD) simulations to analyze the drift velocity of such a balloon-Stratosail system under typical wind conditions in the stratosphere. The Stratosail is attached below the super-pressure helium balloon via a long and thin tether about 10 to 15 km below the balloon, providing a drag force to alter the flight path of the balloon. Its operation depends on the natural differences in the wind speed and wind direction at different altitudes in the atmosphere that act on the balloon and the Stratosail (spaced far apart by 10km to 15 km). In this study, we calculated the drag forces on the balloon and Stratosail for typical wind speeds at various altitudes in the stratosphere. The tether was also modelled as a cable joining the balloon and sail. With this model, the drift velocity of the system was calculated for various altitudes and the angle of attack of the sail.

Numerical Study of a Six-Bladed Savonius Wind Turbine

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Binyet Emmanuel ◽  
Wang Jun
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Numerical Study ◽  
The Self ◽  
Power Coefficient ◽  
Two Dimensional ◽  
Savonius Rotor ◽  
Convex Part ◽  
Computational Fluid Dynamics Cfd ◽  
Savonius Wind Turbine

The aim of the present paper is to investigate ways of improving the efficiency of a six-bladed Savonius rotor. The efficiency of Savonius machines is low because of the “negative drag” exerted on the convex part of the blades and also because the torque of standard Savonius rotors varies substantially during one rotation and therefore affects the self starting of the rotor at certain wind angles. Improvement of the efficiency of the Savonius rotor is carried out by increasing the number of blades and also by preventing the wind from impinging on the convex parts. The latter can be done by hiding the convex part of the blades behind a shield or a vane. The present paper shows the results of two-dimensional computational fluid dynamics (CFD) computations, indicating a promising increase of the power coefficient from 0.3 to 0.5.

Sign in / Sign up

Export Citation Format

Share Document