Numerical study on hydrodynamic forces and course stability of a ship in surf-riding condition based on PMM tests

2021 ◽  
pp. 1-12
Author(s):  
Chengqian Ma ◽  
Ning Ma ◽  
Xiechong Gu ◽  
Peiyuan Feng
Keyword(s):  
Numerical Study ◽  
Theoretical Method ◽  
Hydrodynamic Derivatives ◽  
Course Stability ◽  
Calm Water ◽  
Maneuvering In Waves ◽  
Surf Riding ◽  
Cfd Method ◽  
Wave Induced ◽  
First Time

Abstract The theoretical method, or named the potential flow method, is most widely used in the research of maneuvering in waves. However, this approach used in previous studies is based on the assumption that maneuvering hydrodynamic derivatives in waves are the same as those in calm water. However, this assumption can be inaccurate, which makes the simulations inexact sometimes. Meanwhile, there are few experiments performed to investigate the hydrodynamic derivatives in waves considering the complexities of the experimental setup and data processing. There is even no systematic numerical simulation in this field. Considering the importance of the wave effect on the hydrodynamic derivatives and the advantages of the CFD method, in this study, the numerical simulations of the PMM tests on a containership S175 in regular waves are performed for the first time. The hydrodynamic derivatives in waves are obtained by simulations in the following waves, to be specific, the surf-riding condition. The surf-riding condition is chosen for separating the wave-induced component easily and researching the reason for the broaching-to phenomenon. The simulation results are validated by experimental data with satisfactory accuracy, which indicates the effectiveness of the numerical setup. The results reveal that the wave has a significant effect on hydrodynamic derivatives. The detailed changing trends and simulation methods of all hydrodynamic derivatives are proposed in this paper. Moreover, the course stability in waves is evaluated by the hydrodynamic derivatives in waves, which verifies the reason for the occurrence of the broaching-to phenomenon.

Numerical Simulation on Oblique Towing Tests and Pure Yaw Tests of a Containership in Surf-Riding Condition

2020 ◽  
Author(s):  
Chengqian Ma ◽  
Ning Ma ◽  
Xiechong Gu
Keyword(s):  
Mathematical Model ◽  
Critical Issue ◽  
Wave Effect ◽  
Hydrodynamic Derivatives ◽  
Course Stability ◽  
Mmg Model ◽  
Calm Water ◽  
Maneuvering In Waves ◽  
Surf Riding ◽  
Maneuvering Forces

Abstract Maneuvering in waves is a complex and critical issue that confuses researchers for the last several decades. Among the existing methods for predicting the maneuverability in waves, the widely-used mathematical model approach (MMG model) is considered to be efficient and accurate in large wavelength and small wave steepness conditions. However, based on the assumption that the maneuvering forces in waves are the same as those in calm water, the wave effect on the hydrodynamic derivatives is neglected in most mathematical model approaches. According to the previous theoretical analysis and experimental data, this assumption is flawed. Therefore, several experiments and some numerical simulations have conducted to research the wave effect on hydrodynamic derivatives. In the present study, oblique towing tests and pure yaw tests will be simulated using the state-of-the-art CFD techniques to obtain the linear hydrodynamic derivatives in waves. The simulation cases in the present study are set according to previous PMM tests of S175 containership in surf-riding conditions. And the simulation results are in good agreement with experimental ones. Based on that, the wave effect on hydrodynamic derivatives is obtained and some discussions are made. Finally, the course stability of the containership on the different relative position of the wave are calculated to analyze the preliminary reason for the broaching-to phenomenon.

Hybrid Method for Predicting Ship Manoeuvrability in Regular Waves

2019 ◽  
Author(s):  
Tianlong Mei ◽  
Yi Liu ◽  
Manasés Tello Ruiz ◽  
Marc Vantorre ◽  
Evert Lataire ◽  
...  
Keyword(s):  
Experimental Data ◽  
Hybrid Method ◽  
Potential Flow ◽  
Flow Theory ◽  
Regular Waves ◽  
Potential Flow Theory ◽  
Hydrodynamic Derivatives ◽  
Mmg Model ◽  
Calm Water ◽  
Wave Induced

Abstract The ship’s manoeuvring behaviour in waves is significantly different from that in calm water. In this context, the present work uses a hybrid method combining potential flow theory and Computational Fluid Dynamics (CFD) techniques for the prediction of ship manoeuvrability in regular waves. The mean wave-induced drift forces are calculated by adopting a time domain 3D higher-order Rankine panel method, which includes the effect of the lateral speed and forward speed. The hull-related hydrodynamic derivatives are determined based on a RANS solver using the double body flow model. The two-time scale method is applied to integrate the improved seakeeping model in a 3-DOF modular type Manoeuvring Modelling Group (MMG model) to investigate the ship’s manoeuvrability in regular waves. Numerical simulations are carried out to predict the turning circle in regular waves for the S175 container carrier. The turning circle’s main characteristics as well as the wave-induced motions are evaluated. A good agreement is obtained by comparing the numerical results with experimental data obtained from existing literature. This demonstrates that combining potential flow theory with CFD techniques can be used efficiently for predicting the manoeuvring behaviour in waves. This is even more true when the manoeuvring derivatives cannot be obtained from model tests when there is lack of such experimental data.

scholarly journals S-N Curve Characterisation for Composite Materials and Prediction of Remaining Fatigue Life Using Damage Function

2021 ◽  
Vol 5 (3) ◽  
pp. 76
Author(s):  
Ho Sung Kim ◽  
Saijie Huang
Keyword(s):  
Fatigue Life ◽  
Composite Materials ◽  
Loading Rate ◽  
Theoretical Method ◽  
Damage Function ◽  
Simple Method ◽  
Arbitrary Choice ◽  
Number Of Cycles ◽  
First Time ◽  
Remaining Fatigue Life

S-N curve characterisation and prediction of remaining fatigue life are studied using polyethylene terephthalate glycol-modified (PETG). A new simple method for finding a data point at the lowest number of cycles for the Kim and Zhang S-N curve model is proposed to avoid the arbitrary choice of loading rate for tensile testing. It was demonstrated that the arbitrary choice of loading rate may likely lead to an erroneous characterisation for the prediction of the remaining fatigue life. The previously proposed theoretical method for predicting the remaining fatigue life of composite materials involving the damage function was verified at a stress ratio of 0.4 for the first time. Both high to low and low to high loadings were conducted for predicting the remaining fatigue lives and a good agreement between predictions and experimental results was found. Fatigue damage consisting of cracks and whitening is described.

A Hybrid Numerical Framework for Simulation of Ships Maneuvering in Waves

2021 ◽  
pp. 1-13
Author(s):  
Paul F. White ◽  
Dominic J. Piro ◽  
Bradford G. Knight ◽  
Kevin J. Maki
Keyword(s):  
Hydrodynamic Force ◽  
Linear Time ◽  
Domain Boundary ◽  
Critical Role ◽  
Force Model ◽  
Efficient Computation ◽  
Fast Running ◽  
Surface Ship ◽  
Calm Water ◽  
Maneuvering In Waves

The maneuvering characteristics of a surface ship play a critical role in the safety of navigation both in port and in an open seaway, and are vital to the overall operational ability of the ship. The vast majority of maneuvering analyses for ships have been performed under the assumption of calm water, yet ships mostly operate in waves. Understanding of maneuvering in waves is limited by the complexity of the problem and the challenges of performing physical experiments and numerical simulations. In this work, a new fast-running method that allows for the study of maneuvering in waves is formulated. The newly formulated approach is categorized as a “hybrid method,” taking its name from the multiple numerical methods and force models used to predict the total hydrodynamic force acting on the vessel maneuvering in waves. The framework presented here uses a combination of Computational Fluid Dynamics, a linear time-domain boundary element method, and a propeller-force model for efficient computation of the total hydrodynamic force.

An experimental and numerical study of the resonant flow between a hull and a wall

2021 ◽  
Vol 930 ◽  
Author(s):  
I.A. Milne ◽  
O. Kimmoun ◽  
J.M.R. Graham ◽  
B. Molin
Keyword(s):  
Vortex Shedding ◽  
Particle Image ◽  
Numerical Study ◽  
Numerical Models ◽  
Vertical Wall ◽  
Liquefied Natural Gas ◽  
Narrow Gap ◽  
Image Velocimetry ◽  
High Degree ◽  
Wave Induced

The wave-induced resonant flow in a narrow gap between a stationary hull and a vertical wall is studied experimentally and numerically. Vortex shedding from the sharp bilge edge of the hull gives rise to a quadratically damped free surface response in the gap, where the damping coefficient is approximately independent of wave steepness and frequency. Particle image velocimetry and direct numerical simulations were used to characterise the shedding dynamics and explore the influence of discretisation in the measurements and computations. Secondary separation was identified as a particular feature which occurred at the hull bilge in these gap flows. This can result in the generation of a system with multiple vortical regions and asymmetries between the inflow and outflow. The shedding dynamics was found to exhibit a high degree of invariance to the amplitude in the gap and the spanwise position of the barge. The new measurements and the evaluation of numerical models of varying fidelity can assist in informing offshore operations such as the side by side offloading from floating liquefied natural gas facilities.

scholarly journals Numerical Study on Hydrodynamic Force and Wave Induced Vortex Dynamics around Cylindrical Pile

2018 ◽  
Vol 1 (4) ◽  
pp. 1-11 ◽  
Author(s):  
Mohammad Mohammad Beigi Kasvaei ◽  
◽  
Mohammad Hossein Kazeminezhad ◽  
Abbas Yeganeh-Bakhtiary ◽  
◽  
...  
Keyword(s):  
Vortex Dynamics ◽  
Hydrodynamic Force ◽  
Numerical Study ◽  
Wave Induced

Numerical study for wave-induced oscillatory pore pressures and liquefaction around impermeable slope breakwater heads

2018 ◽  
Vol 157 ◽  
pp. 364-375 ◽  
Author(s):  
Chencong Liao ◽  
Dagui Tong ◽  
Dong-Sheng Jeng ◽  
Hongyi Zhao
Keyword(s):  
Numerical Study ◽  
Pore Pressures ◽  
Wave Induced

Numerical study on wave-induced hydro-elastic responses of a floating raft for aquaculture

2021 ◽  
Vol 240 ◽  
pp. 109869
Author(s):  
Bei Chu ◽  
Yiren Chen ◽  
Yao Zhang ◽  
Guangming Zhang ◽  
Xu Xiang ◽  
...  
Keyword(s):  
Numerical Study ◽  
Floating Raft ◽  
Elastic Responses ◽  
Wave Induced

Abnormal Wave-Induced Load Effects in Ship Structures

2008 ◽  
Vol 52 (01) ◽  
pp. 30-44 ◽  
Author(s):  
C. Guedes Soares ◽  
N. Fonseca ◽  
R. Pascoal
Keyword(s):  
Extreme Values ◽  
Time History ◽  
Design Criterion ◽  
Freak Waves ◽  
Reference Design ◽  
Load Effects ◽  
Central North Sea ◽  
Wave Induced ◽  
First Time

The paper presents an approach to determine the global load effects induced on shif structures by abnormal, freak, or episodic waves. It refers to the present procedure of determining extreme values of wave-induced responses, including the recent advances of adopting time series of wave elevation as reference design conditions t calculate the wave-induced structural loads on ships in heavy weather. It is show how this procedure can be extended to account for abnormal or episodic waves Reference is made to what is presently known about abnormal or freak waves showing that although it is possible to determine the loads induced by these wave in floating and fixed structures, the present knowledge about the probability of occurrence of these waves is not enough to allow a wave design criterion to be defined in a way consistent with the present probabilistic approaches. However, it is suggested that at the present stage of knowledge it is possible to determine the load induced by abnormal waves similar to ones that have been measured at various ocean locations and that are thus realistic; a method is described to perform such calculations. Although this information cannot replace the wave-induced loads calculated with the presently established procedures, it can serve as guidance for th design. An application example is presented of a containership subjected to a wav trace that includes an episodic wave that was measured during a severe storm in Central North Sea. The measured wave time history is modified in order to investigate the influence of the wave steepness on the induced vertical motions and loads. Th loads induced by the abnormal wave are compared for the first time with extreme values from long-term distributions.

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