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Simulation of violent free surface flow by AMR method

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Journal of Hydrodynamics 2018年第3期30卷 384-389页

作者： changhong hu Cheng Liu Research Institute for Applied Mechanics Kyushu University Fukuoka Japa

A novel CFD approach based on adaptive mesh refinement（AMR） technique is being developed for numerical simulation of violent free surface flows. CIP method is applied to the flow solver and tangent of hyperbola for interface capturing with slope weighting（THINC/SW） scheme is implemented as the free surface capturing scheme. The PETSc library is adopted to solve the linear system. The linear solver is redesigned and modified to satisfy the requirement of the AMR mesh topology. In this paper, our CFD method is outlined and newly obtained results on numerical simulation of violent free surface flows are presented.

关键词： Adaptive mesh refinement CIP method parallel computation violent free surface flow

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CFD simulation of tidal current farm by using AL model

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Journal of Hydrodynamics 2019年第1期31卷 34-40页

作者： Cheng Liu changhong hu Research Institute for Applied Mechanics Kyushu UniversityFukuokaJapan

In this study,an efficient numerical method for predicting the wake interference of multiple turbines is *** actuator line (AL) model instead of the geometry-resolved method is adopted to represent the *** large-eddy simulation (LES) is performed to predict wakes of multiple turbines operated in turbulent *** efficient immersed boundary (IB) method with moving least square reconstruction (MLS) is developed to model the nacelle and support structure of the tidal turbine.A simple wall function based on the MLS-IB method and boundary-layer equations is employed to compute the instantaneous wall shear *** flow simulations of unsteady flows past a cylinder illustrate the accuracy of the wall function IB ***,the proposed method is extended to study turbulent flow past tandem tidal rotors,in which the wake profile behind rotors is *** results are found to be in reasonable agreement with published data.

关键词： Tidal current farm immersed boundary method wall fimction model large eddy simulation (LES) actuator line model

Development of Cartesian grid method for simulation of violent ship-wave interactions

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Journal of Hydrodynamics 2016年第6期28卷 1003-1010页

作者： changhong hu Cheng LIU Research Institute for Applied Mechanics Kyushu University

We present a Cartesian grid method for numerical simulation of strongly nonlinear phenomena of ship-wave interactions. The Constraint Interpolation Profile （CIP） method is applied to the flow solver, which can efficiently increase the discretization accuracy on the moving boundaries for the Cartesian grid method. Tangent of Hyperbola for Interface Capturing （THINC） is imple- mented as an interface capturing scheme for free surface calculation. An improved immersed boundary method is developed to treat moving bodies with complex-shaped geometries. In this paper, the main features and some recent improvements of the Cartesian grid method are described and several numerical simulation results are presented to discuss its performance.

关键词： strongly nonlinear wave-body interaction Cartesian grid method CIP method

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An unstructured mesh method for numerical simulation of violent sloshing flows

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Journal of Hydrodynamics 2020年第2期32卷 259-266页

作者： changhong hu Mohamed M.Kamra Research Institute for Applied Mechanics Kyushu UniversityFukuokaJapan

An unstructured mesh Reynolds-averaged Navier-Stokes(RANS)solver has been developed for numerical simulation of violent sloshing flows inside a tank with complicated inner *** numerical solver employs the unstructured multi-dimensional tangent hyperbolic interface capturing method(UMTHINC)for free-surface capturing combined with various turbulence *** sloshing motion is numerically modeled using the body-force method which introduces a source term into the momentum equation corresponding to the tank motion *** simulations of the tank sloshing problems are performed for different test cases with various oscillation *** performance of the interface capturing method has been discussed and the effect of turbulence model choice on loading predictions is highlighted by studying several RANS models and analyzing its effect on fluid motion and impact *** simulations of the sloshing inside the tank with a vertical baffle has also been conducted and a discussion is provided on different numerical treatment of the baffle.

关键词： Unstructured mesh RNAS solver UMTHINC scheme violent sloshing flow

Numerical simulation of dam break flow impact on vertical cylinder by cumulant lattice Boltzmann method

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Journal of Hydrodynamics 2021年第2期33卷 185-194页

作者： Seiya Watanabe Shintaro Fujisaki changhong hu Research Institute for Applied Mechanics Kyushu UniversityFukuokaJapan School of Engineering Sciences Kyushu UniversityFukuokaJapan

The purpose of this study is to apply the cumulant lattice Boltzmann method(LBM)to simulate high Reynolds number free surface *** single-phase cumulant LBM is extended to solve the free surface flows by using the phase-field method as the interface capturing *** simulations are performed on an experimental problem of dam break flow impact on a vertical *** numerical aspects such as collision model,grid resolution,time step and interface mobility parameter are *** is found that the severe impact pressure oscillation in the simulation by the conventional SRT model,can be significantly suppressed by the cumulant *** agreement between the cumulant LBM numerical simulation and the experiment has been obtained on both the free surface profiles and the impact *** numerical results obtained by the present study demonstrate that the cumulant LBM can be a powerful numerical tool for simulations of violent free surface flow problems.

关键词： Lattice Boltzmann method(LBM) free surface flow wave impact pressure dam break flow cumulant model

Knowledge-Domain Semantic Searching and Recommendation Based on Improved Ant Colony Algorithm

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Journal of Bionic Engineering 2013年第4期10卷 532-540页

作者： Mingyang Liu Shufen Liu Xiaoyan Wang Ming Qu changhong hu College of Computer Science and Technology Jilin University Changchun 130012 P. R. China

To obtain accurate search results and advocate the use of human effort in discovering knowledge, we propose a method based on Ant Colony Algorithm （ACA）. The proposed method simulates the behavior of ants searching for food. Specific features such as the behavior of ants searching for food, their established search paths, and the ant ＂neighborhood＂ profile are investigated. The investigation results reveal that the behavior of people searching for useful information resembles that of ants searching for food. We also use semantic annotation and the decreasing matrix dimension approach to accelerate the food searching process an.d shorten the distance between the query starting points and the ultimate answers. A user behavior model is constructed based on personal and domain ontologies. Experimental evaluation with the enhanced ACA has two parts：（1） estimating the efficiency of information retrieval with user interests considered and （2） identifying how to weigh usage and rate user data during recommendation.

关键词： Ant Colony Algorithm (ACA) search ontology Knowledge Advantage Machine (KaM) Collaborative Filtering (CF) Singular Value Decomposition (SVD)

Numerical and experimental investigation of three-dimensionality in the dam-break flow against a vertical wall

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Journal of Hydrodynamics 2018年第4期30卷 682-693页

作者： Mohamed M.Kamra Nik Mohd Cheng Liu Makoto Sueyoshi changhong hu Interdisciplinary Graduate School of Engineering Seieneesl Kyushu University Kasuga Fukuoka Japan Research Institute for Applied Mechanics Kyushu University Kasuga Fukuoka Japan

The three-dimensionality extent of the dam break flow over a vertical wall is investigated numerically and experimentally in this paper. The numerical method is based on Reynolds averaged Navier-Stokes（RANS） equation that describes the three-dimensional incompressible turbulent flow. The free surface is captured by using the unstructured multi-dimensional interface capturing（UMTHINC） scheme. The equations are discretized on 2-D and 3-D unstructured grids using finite volume method. The numerical simulations are compared with newly conducted experiment with emphasis on the effect of three-dimensionality on both free surface and impact pressure. The comparison between the numerical and experimental results shows good agreement. Furthermore, the results also show that 3-D motion of the flow originates at the moment of impact at the lower corners of the impact wall and propagates to the inner region as time advances. The origin of the three-dimensionality is found to be the turbulence development as well as the relative velocity between the side wall region and the inner region of the wave front at the moment of impact.

关键词： Water impact dam break flow UMTHINC scheme three-dimensionality

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Two-stage Correction Strategy-based Real-time Dispatch for Economic Operation of Microgrids

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Chinese Journal of Electrical Engineering 2022年第2期8卷 42-51页

作者： Jingliao Sun changhong hu Lei Liu Bei Zhao Jinyuan Liu Jianquan Shi Wenzhou Power Supply Company State Grid Zhejiang Electric Power Co.Ltd.Wenzhou 325028China School of Electrical Engineering Xi’an Jiaotong UniversityXi’an 710049China School of Automation Nanjing Institute of TechnologyNanjing 211167China

Given the different energy rates of multiple types of power generation units,different operation plans affect the economy of *** by load and power generation forecasting technologies,the economic superiority of day-ahead plans is unable to be fully utilized because of the fluctuation of loads and power *** this regard,a two-stage correction strategy-based real-time dispatch method for the economic operation of microgrids is *** on the optimal day-ahead economic operation plan,unbalanced power is validly allocated in two stages in terms of power increment and current power,which maintains the economy of the day-ahead ***,for operating point offset during real-time correction,a rolling dispatch method is introduced to dynamically update the system operation ***,the results verify the effectiveness of the proposed method.

关键词： Real-time dispatch day-ahead operation plan economic operation microgrid

Decision-Level Defect Prediction Based on Double Focuses

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Chinese Journal of Electronics 2017年第2期26卷 256-262页

作者： hu changhong XUE Xucheng huANG Liang LYU Hengyi WANG Heqi LI Xiangzhi LIU Hailong SUN Ming SUN Wu Changchun Institute of Optics Fine Mechanics and PhysicsChinese Academy of Sciences University of Chinese Academy of Sciences

This research mainly expounds upon the decision-level software defect prediction *** defect characteristics is the first research *** the first research focus,a characteristic comparison set is built out of the existing defect characteristics according to the dissimilarity of defect characteristics and the defect characteristics are organized outside the characteristic comparison set into some defect characteristic clusters to reduce the scale of the characteristic *** defects is the second research *** the second research focus,the vector weights are assigned to the defect characteristics contained in the defects according to the minimum critical characteristic ***,the multi-agent algorithm integration technology is used to predict defects according to the repulsive relationship between similar defect clusters.

关键词： Decision Prediction Defect Focus