scholarly journals Study on Green Water of Tumblehome Hull Using Dam-Break Flow and Ranse Models

2017 ◽  
Vol 24 (s2) ◽  
pp. 172-180
Author(s):  
Shuzheng Sun ◽  
Wenlei Du ◽  
Hui Li
Keyword(s):  
Numerical Simulation ◽  
Cfd Simulation ◽  
Wave Interaction ◽  
Simulation Method ◽  
Dam Break ◽  
Green Water ◽  
Nonlinear Phenomenon ◽  
Numerical Simulation Methods ◽  
Dam Break Flow ◽  
Water Problems

Abstract The tumblehome hull adopts some novelty designs such as low-tumblehome freeboard and wave-piercing bow. The new form design makes the ship have many special hydrodynamic performances. Especially the green water of tumblehome hull is different from that of hulls with flare free board. Green water is a strong nonlinear phenomenon of ship-wave interaction, the variation of free surface of liquid is complicated, and there are still some difficulties to solve green water problems well with numerical simulation method. In this paper firstly the motion responses of the tumblehome hull was calculated based on 3D potential theory, and then the dam-break flow model was used to calculate green water height and pressure distribution. According to the result of numerical simulation, some typical working conditions are chosen for 3D CFD simulation using RANS method. The results of numerical simulation methods are compared with the experimental results measured in towing tank. The influence of different ship form parameters and wave parameters to the green water of tumblehome hull is analyzed, and some regularities of green water on tumblehome hull in regular waves are summarized.

Numerical Simulation of Scouring in Overtopping Dam-break Flow

2021 ◽  
Author(s):  
Can Huang ◽  
Xiaoliang Wang ◽  
Qingquan Liu
Keyword(s):  
Numerical Simulation ◽  
Empirical Relationship ◽  
Dam Break ◽  
Experimental Conditions ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Dam Break Flow ◽  
Scouring Process ◽  
Overtopping Erosion ◽  
Good Agreement

<p>Overtopping dam-break flow has great harm to the earthen embankments due to the hydraulic erosion. Some researchers have carried out relevant model experiments, but it is difficult to achieve the experimental conditions for the actual situation. The common numerical simulation is to express the scouring process through the empirical relationship, which obviously could not reflect the real scouring process. In this paper, a new overtopping erosion model using Smoothed Particle Hydrodynamics (SPH) is proposed. When the shear stress on the sediment SPH particle exceeds the critical stress, the erosion process begins. Then, when a sediment SPH particle is completely eroded, it will begin to move and is described as a non-Newtonian fluid. The un-incipient sediment particles are treated as boundary. This model is well validated with plane dike-breach experiment, and has also achieved a good agreement with erodible bed dam-break experiment.</p>

Elaborate Simulation Method for the Influence of Soil Excavation of Shield Tunnels on Existing Pile Foundations

2010 ◽  
Vol 168-170 ◽  
pp. 270-275
Author(s):  
Rong Jun Zhang ◽  
Jun Jie Zheng ◽  
You Kou Dong
Keyword(s):  
Numerical Simulation ◽  
Simulation Method ◽  
Simulation Methods ◽  
Cyclic Shear ◽  
Numerical Simulation Methods ◽  
Shear Characteristics ◽  
Shield Tunnelling ◽  
Soil Excavation ◽  
Soil Interface

Existing numerical simulation methods tend to neglect some details of shield tunnelling and the cyclic shear characteristics of pile-soil interface. In this paper, an elaborate simulation method is firstly proposed to simulate the advancing of shield machines according to the details of shield tunnelling. Then an improved constitutive model for pile-soil interface, which can factually consider the cyclic shear characteristics, is also developed. Finally, through a case study, it can be found that the proposed simulation method can provide reliable estimation for this problem, and it is important to factually consider the cyclic shear characteristics of pile-soil interface.

Methodology for Designing Low-Vibration Structures for Movable Mechanisms

1999 ◽  
Author(s):  
Shinobu Yoshida ◽  
Yoshiko Kawabe
Keyword(s):  
Numerical Simulation ◽  
Vibration Analysis ◽  
Simulation Method ◽  
Optimization Method ◽  
Structural Vibration ◽  
Simulation Methods ◽  
Analysis Method ◽  
Module Design ◽  
Numerical Simulation Methods ◽  
Design Steps

Abstract The methodology dealt with here is the way how to use numerical simulation methods corresponding to different design steps. The methods are a budget simulation method for mechanical specification design step, a structural vibration analysis method using a finite element method and an optimization method. The latter two methods are used for the module design and parts design steps. Case studies reviewing the works of authors show the effectiveness of the methodology.

scholarly journals Experimental and Numerical Research on the Influence of Stern Flap Mounting Angle on Double-Stepped Planing Hull Hydrodynamic Performance

2019 ◽  
Vol 7 (10) ◽  
pp. 346 ◽  
Author(s):  
Zou ◽  
Lu ◽  
Jiang ◽  
Sun ◽  
Li
Keyword(s):  
Numerical Simulation ◽  
Critical Speed ◽  
Simulation Method ◽  
Hydrodynamic Performance ◽  
Water Mixture ◽  
Mixture Flow ◽  
Resistance Reduction ◽  
Numerical Simulation Methods ◽  
Numerical Research ◽  
Resistance Performance

In the current hydrodynamic research relating to planing hulls, the stern flap and steps are generally considered to be two independent resistance reduction measures. Limited research has focused on the coupled effects of flaps and steps. Therefore, experimental and numerical simulation methods are carried out in this paper to explore the influence of the flap mounting angle coupled with the steps. A series of model towing tests were implemented for a double-stepped planing hull with 2°, 3° and 4.5° flap angles. The test results show that, as the mounting angle increased, the low speed resistance performance was improved and the porpoising critical speed was delayed, with a slight resistance cost. Based on the tests, a numerical simulation method was established with volume Froude numbers ranging from 0.88 to 5.20. The simulated hull flow field showed good agreement with the testing data. The simulation results suggest a cavity induces the negative pressure after the steps; the cavity core region is the air phase, and this expands with the air–water mixture flow. The cavity also causes wetted surface reduction and pressure distribution changes. Finally, comparisons of cavities after-steps and load coefficients of different planing surfaces among models were considered. Numerical results analysis gave distinct interpretations for the experimental phenomenon of porpoising critical speed increasing with a slight resistance increment.

Numerical simulation of dam-break flow and bed change considering the vegetation effects

2017 ◽  
Vol 32 (1) ◽  
pp. 105-120 ◽  
Author(s):  
Zhiguo He ◽  
Ting Wu ◽  
Haoxuan Weng ◽  
Peng Hu ◽  
Gangfeng Wu
Keyword(s):  
Numerical Simulation ◽  
Dam Break ◽  
Vegetation Effects ◽  
Dam Break Flow
Sign in / Sign up

Export Citation Format

Share Document