scholarly journals Hydrodynamic Analysis of KVLCC2 Ship Sailing near Inclined Banks

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Weilin Luo ◽  
Bing Yang ◽  
Yafeng Sun
Keyword(s):  
Numerical Simulation ◽  
Unstructured Grid ◽  
Transverse Force ◽  
Hydrodynamic Characteristics ◽  
Bank Angle ◽  
Hydrodynamic Analysis ◽  
Drift Angle ◽  
Tetrahedral Grid ◽  
Simulation Results ◽  
Yaw Moment

The hydrodynamic forces of KVLCC2 ship sailing near inclined banks are calculated by using CFD based on RANS equation. Corresponding CFD uncertainty analysis is conducted according to the procedure recommended by ITTC. An unstructured grid, tetrahedral grid, is employed for discretization. To control the number of grids, global element scale factor is selected as the same as refinement ratio. In numerical simulation, straightforward and oblique navigation conditions are investigated. The variation of transverse force and yaw moment with the ship-shore distance, bank angle, water depth, and drift angle are analyzed. Both hull model and hull-propeller-rudder model are considered in numerical simulation. The simulation results show the hydrodynamic characteristics of ship sailing near inclined banks.

Hydrodynamic Characteristics of Dislocated Floating Ring Bearing with Different Eccentricities

2011 ◽  
Vol 52-54 ◽  
pp. 152-155
Author(s):  
Yu Jie Dai
Keyword(s):  
Numerical Simulation ◽  
Boundary Element Method ◽  
Internal Friction ◽  
Boundary Element ◽  
Hydrodynamic Characteristics ◽  
Ring Radius ◽  
Simulation Results ◽  
Element Method

For obtain the effect of floating ring radius R2 and floating ring velocity v2 on internal friction in dislocated floating ring with different eccentricities, the evolution of internal friction is simulated with boundary element method (BEM). Numerical simulation results show that internal friction increases with the increase of eccentricity. Internal friction rises linearly as the addition of floating ring velocity v2 if the eccentricity e and radius R2 are fixed. When the velocity v2 is a constant and the range of R2 is 0.75<R2<0.8, the internal friction increase enormously.

scholarly journals Numerical Simulation Analysis of Cavitation Performance of Tandem Propeller

2018 ◽  
Vol 36 (3) ◽  
pp. 509-515 ◽  
Author(s):  
Xiaoxu Du ◽  
Zhengdong Zhang
Keyword(s):  
Numerical Simulation ◽  
Simulation Analysis ◽  
Cavitation Number ◽  
Hydrodynamic Characteristics ◽  
Turbulent Model ◽  
Cavitation Model ◽  
Cavitation Phenomenon ◽  
Cavitation Performance ◽  
Simulation Results ◽  
Good Agreement

The steady non cavitation hydrodynamic characteristics of CLB4-55-1 tandem propeller and the steady cavitation flows of NACA66 hydrofoil are numerically studied firstly based on the RANS equations of homogeneous multiphase using CFD theory, combined with the SST k-ω turbulent model and Z-G-B cavitation model. Numerical simulation results are in good agreement with the experimental results, which indicates that the numerical method is reliable and accurate. Then, the cavitation performance of the tandem propeller are numerical simulated and analyzed. The results show that the computational model can predict the cavitation performance of tandem propeller accurately. The cavitation performance of tandem propeller is nearly the same as single propeller, however, the cavitation phenomenon of back propeller is greater than the head propeller at certain advance coefficient and cavitation number. The cavitation phenomenon will disappear with the increase of the advance coefficient or the cavitation number.

Numerical Simulation of Bionic Locomotor Batoid with Combined Frequency Undulating Pectoral Fins

2013 ◽  
Vol 364 ◽  
pp. 346-351
Author(s):  
Zhi Jun Wu ◽  
Wei Shan Chen ◽  
Sheng Jun Shi ◽  
Dan Xia
Keyword(s):  
Numerical Simulation ◽  
Rigid Body ◽  
Frequency Conversion ◽  
Uniform Thickness ◽  
Propulsive Efficiency ◽  
Hydrodynamic Analysis ◽  
Pectoral Fins ◽  
Fin Ray ◽  
Simulation Results ◽  
Motion Design

Batoids propel themselves forward by generating waves along their large pectoral fins. According to the observation of batoids in nature, the frequency of the wave on the pectoral fins is not always invariable. The bionic batoid is composed of rigid body and flexible pectoral fins of uniform thickness. In this study the hydrodynamic analysis of bionic batoid with combined frequency specified on the pectoral fins are presented. The combined frequency is implemented by the frequency conversion during the oscillation of each pectoral fin ray. Since oscillating frequency of 2.2Hz is mostly observed in rajiform batoid, the variable frequencies ranging from 1.0Hz to 2.6Hz with 0.4Hz increment compound 2.2Hz and formed five different sets of combined frequency. The simulation results illustrate that the bionic batoid model with combined frequency locomotion can achieve better propulsive efficiency, which maybe benefit for the motion design of bionic robot batoid.

Investigation on Influence of Launch Depth to the Hydrodynamic Characteristics of the Cylinder out of the Tube

2011 ◽  
Vol 328-330 ◽  
pp. 2261-2264
Author(s):  
Hai Jun Liu ◽  
Xing Zhi Peng ◽  
Cong Wang ◽  
Ben Li Wang
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Resistance Coefficient ◽  
Viscous Drag ◽  
Hydrodynamic Characteristics ◽  
Multiphase Model ◽  
Pressure Drag ◽  
Simulation Results ◽  
Volume Method ◽  
Mesh Technique

The influence of different the depth to the hydrodynamic characteristics of the underwater cylinder vertical launch out of the tube was researched with numerical simulation. The finite volume method based on the multiphase model, continuity equation, transport equations of liquid mass fraction,a dynamic mesh technique and a standard tow-turbulence model are adopted to solve RANS equation in conjunction. The fluid-solid coupling problem of both movement boundary of the cylinder and multiphase flow field was solved by using numerical method. Under the influence of the gravity, the flow field affected the hydrodynamic characteristics of the cylinder was derived with the numerical simulation. Simulation results show that different launch depths affect on the trajectory of underwater cylinder and hydrodynamic. The fluctuation reasons of different pressure drag coefficient, viscous drag resistance coefficient and toll resistance coefficient were derived by analyzing simulation results.

Numerical Calculation of Hydrodynamic Interference Coefficients between Hull, Rudder and Propeller

2012 ◽  
Vol 591-593 ◽  
pp. 1949-1953 ◽  
Author(s):  
Xiao Wang ◽  
Ming Wu ◽  
Rong Rong Ying
Keyword(s):  
Numerical Simulation ◽  
Numerical Calculation ◽  
Flow Field ◽  
Interference Effect ◽  
Longitudinal Velocity ◽  
Transverse Force ◽  
Navier Stokes ◽  
Straight Line ◽  
Simulation Results ◽  
Viscous Flow Field

CFD developed rapidly in capability and practicality during past years. A lot of research works on numerical simulation of viscous flow field around ship were widely carried out in past decades. But the research of interference effect among the hull, rudder and propeller was rarely concerned. In this paper, based on an unsteady Reynolds Averaged Navier–Stokes method, the dynamic mesh methods(6DOF) are adopted to simulate straight line and oblique towing test of ship with twin propellers and twin rudders. And based on the simulation results, the interference coefficients, such as effective weak coefficient ωp, rudder’s effective longitudinal velocity uR, effective attack angle αR, rudder force’s modificatory factor αH for shiphandling derivational transverse force and its dimensionless distance to ship’s gravity point, are calculated. The computed results of this paper agree well with the experimental results carried out in the tower tank of ITTC. It shows that the methods on numerical calculation of Interference Coefficients between hull, rudder and propeller is successful.

Avalanche Features in Silicon Schottky-FETs in Accordance with Numerical Simulation Results

2006 ◽  
Vol 65 (16) ◽  
pp. 1533-1546
Author(s):  
Yu. Ye. Gordienko ◽  
S. A. Zuev ◽  
V. V. Starostenko ◽  
V. Yu. Tereshchenko ◽  
A. A. Shadrin
Keyword(s):  
Numerical Simulation ◽  
Simulation Results

Tail shapes lead to different propulsive mechanisms in the body/caudal fin undulation of fish

2020 ◽  
pp. 095440622096768
Author(s):  
Jialei Song ◽  
Yong Zhong ◽  
Ruxu Du ◽  
Ling Yin ◽  
Yang Ding
Keyword(s):  
Numerical Simulation ◽  
Aspect Ratio ◽  
High Efficiency ◽  
The Body ◽  
Caudal Fin ◽  
Fish Model ◽  
Swimming Efficiency ◽  
Simulation Results ◽  
Propulsive Mechanism ◽  
High Depth

In this paper, we investigate the hydrodynamics of swimmers with three caudal fins: a round one corresponding to snakehead fish ( Channidae), an indented one corresponding to saithe ( Pollachius virens), and a lunate one corresponding to tuna ( Thunnus thynnus). A direct numerical simulation (DNS) approach with a self-propelled fish model was adopted. The simulation results show that the caudal fin transitions from a pushing/suction combined propulsive mechanism to a suction-dominated propulsive mechanism with increasing aspect ratio ( AR). Interestingly, different from a previous finding that suction-based propulsion leads to high efficiency in animal swimming, this study shows that the utilization of suction-based propulsion by a high- AR caudal fin reduces swimming efficiency. Therefore, the suction-based propulsive mechanism does not necessarily lead to high efficiency, while other factors might play a role. Further analysis shows that the large lateral momentum transferred to the flow due to the high depth of the high- AR caudal fin leads to the lowest efficiency despite the most significant suction.

scholarly journals Experiment and simulation about the effect of wear-ring abrasion on the performance of a marine centrifugal pump

2021 ◽  
Vol 13 (2) ◽  
pp. 168781402199811
Author(s):  
Wu Xianfang ◽  
Du Xinlai ◽  
Tan Minggao ◽  
Liu Houlin
Keyword(s):  
Numerical Simulation ◽  
Centrifugal Pump ◽  
Pressure Pulsation ◽  
Vibration Velocity ◽  
Test Results ◽  
Obvious Effect ◽  
Performance Change ◽  
Pump Test ◽  
Simulation Results ◽  
Axis Passing

The wear-ring abrasion can cause performance degradation of the marine centrifugal pump. In order to study the effect of front and back wear-ring clearance on a pump, test and numerical simulation were used to investigate the performance change of a pump. The test results show that the head and efficiency of pump decrease by 3.56% and 9.62% respectively at 1.0 Qd due to the wear-ring abrasion. Under 1.0 Qd, with the increase of the front wear-ring the vibration velocity at pump foot increases from 0.4 mm/s to 1.0 mm/s. The axis passing frequency (APF) at the measuring points increases significantly and there appears new characteristic frequency of 3APF and 4APF. The numerical simulation results show that the front wear-ring abrasion affects the flow at the inlet of the front chamber of the pump and impeller passage. And the back wear-ring abrasion has obvious effect on the flow in the back chamber of the pump and impeller passage, while the multi-malfunction of the front wear-ring abrasion and back wear-ring abrasion has the most obvious effect on the flow velocity and flow stability inside pump. The pressure pulsation at Blade Passing Frequency (BPF) of the three schemes all decrease with the increase of the clearance.

scholarly journals Development of Depth-Limited Wave Boundary Layers over a Smooth Bottom

2020 ◽  
Vol 9 (1) ◽  
pp. 27
Author(s):  
Hitoshi Tanaka ◽  
Nguyen Xuan Tinh ◽  
Xiping Yu ◽  
Guangwei Liu
Keyword(s):  
Numerical Simulation ◽  
Boundary Layer ◽  
Boundary Layers ◽  
Wave Motion ◽  
Numerical Study ◽  
Experiment Data ◽  
Tidal Motion ◽  
Long Period ◽  
Simulation Results ◽  
Wave Boundary

A theoretical and numerical study is carried out to investigate the transformation of the wave boundary layer from non-depth-limited (wave-like boundary layer) to depth-limited one (current-like boundary layer) over a smooth bottom. A long period of wave motion is not sufficient to induce depth-limited properties, although it has simply been assumed in various situations under long waves, such as tsunami and tidal currents. Four criteria are obtained theoretically for recognizing the inception of the depth-limited condition under waves. To validate the theoretical criteria, numerical simulation results using a turbulence model as well as laboratory experiment data are employed. In addition, typical field situations induced by tidal motion and tsunami are discussed to show the usefulness of the proposed criteria.

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