Efficient and Accurate 3-D Numerical Modelling of Landslide Tsunami

High-speed and accurate simulations of landslide-generated tsunamis are of great importance for the understanding of generation and propagation of water waves and for prediction of these natural disasters. A three-dimensional numerical model, based on Reynolds-averaged Navier–Stokes equations, is developed to simulate the landslide-generated tsunami. Available experiment data is used to validate the numerical model and to investigate the scale effect of numerical model according to the Froude similarity criterion. Based on grid convergence index (GCI) analysis, fourteen cases are arranged to study the sensitivity of numerical results to mesh resolution. Results show that numerical results are more sensitive to mesh resolution in near field than that in the propagation field. Nonuniform meshes can be used to balance the computational efficiency and accuracy. A mesh generation strategy is proposed and validated, achieving an accurate prediction and nearly 22 times reduction of computational cost. Further, this strategy of mesh generation is applied to simulate the Laxiwa Reservoir landslide tsunami. The results of this study provide an important guide for the establishment of a numerical model of the real-world problem of landslide tsunami.

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Numerical Study of Hydrodynamic Forces on a Submarine Piggyback Pipeline Under Wave Action

Volume 3: Pipeline and Riser Technology ◽

10.1115/omae2012-83214 ◽

2012 ◽

Cited By ~ 1

Author(s):

Xiaofei Cheng ◽

Yongxue Wang ◽

Bing Ren ◽

Guoyu Wang

Keyword(s):

Finite Element Method ◽

Finite Element ◽

Numerical Model ◽

Stokes Equations ◽

Numerical Study ◽

Hydrodynamic Forces ◽

Wave Action ◽

Numerical Results ◽

Physical Model Test ◽

Element Method

In the paper, a 2D numerical model is established to simulate the hydrodynamic forces on a submarine piggyback pipeline under regular wave action. The two-dimensional Reynolds-averaged Navier-Stokes equations with a κ-ω turbulence model closure are solved by using a three-step Taylor-Galerkin finite element method (FEM). A Computational Lagrangian-Eulerian Advection Remap Volume of Fluid (CLEAR-VOF) method is employed to simulate free surface problems, which is inherently compatible with unstructured meshes and finite element method. The numerical results of in-line force and lift (transverse) force on the piggyback pipeline for e/D = G/D = 0.25 and KC = 25.1 are compared with physical model test results, which are conducted in a marine environmental flume in the State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology, China. It is indicated that the numerical results coincide with the experimental results and that the numerical model can be used to predict the hydrodynamic forces on the piggyback pipeline under wave action. Based on the numerical model, the surface pressure distribution and the motion of vortices around the piggyback pipeline for e/D = G/D = 0.25, KC = 25.1 are investigated, and a characteristic vortex pattern around the piggyback pipeline denoted “anti-phase-synchronized” pattern is recognized.

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Development and validation of a hybrid method for predicting helicopter rotor impulsive noise

Proceedings of the Institution of Mechanical Engineers Part G Journal of Aerospace Engineering ◽

10.1177/0954410018756476 ◽

2018 ◽

Vol 233 (4) ◽

pp. 1323-1339 ◽

Cited By ~ 1

Author(s):

Liangquan Wang ◽

Guohua Xu ◽

Yongjie Shi

Keyword(s):

Hybrid Method ◽

High Speed ◽

Stokes Equations ◽

Impulsive Noise ◽

Computational Cost ◽

Helicopter Rotor ◽

Aerodynamic Load ◽

Vortex Interaction ◽

Blade Vortex Interaction ◽

Hybrid Solver

Prediction of helicopter rotor impulsive noise is practically a very challenging task. This paper describes a hybrid method to predict rotor impulsive noise for both high-speed impulsive noise and blade–vortex interaction noise. The hybrid solver has been developed by combining the advantages of three different methods: (1) a computational fluid dynamics method based on Reynolds-averaged Navier–Stokes equations to account for the viscous and compressible effects near the blade; (2) a vorticity transport model to predict rotor wake system without artificial dissipation; and (3) an acoustic calculation method, based on Ffowcs-Williams Hawkings equation implemented to a permeable data surface. The developed hybrid solver is validated through available test data, for the cases of UH-1H model rotor, AH-1 Operational Loads Survey rotor, and Helishape 7A rotor. Peak sound pressure level of high-speed impulsive noise is accurately predicted with relative errors less than 7%. Additionally, acoustic waveform of blade–vortex interaction noise is well captured though it is sensitive to small changes in aerodynamic load. It is suggested that present hybrid method is versatile for the prediction of rotor impulsive noise with moderate computational cost.

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Numerical modeling of fluid resonance in narrow gaps of fixed rectangular structures

Advances in Mechanical Engineering ◽

10.1177/1687814019872302 ◽

2019 ◽

Vol 11 (8) ◽

pp. 168781401987230

Author(s):

Ming-ming Liu ◽

Rui-jia Jin ◽

Zhen-dong Cui

Keyword(s):

Free Surface ◽

Numerical Model ◽

Stokes Equations ◽

Theoretical Data ◽

Numerical Results ◽

Two Dimensional ◽

Arbitrary Lagrangian Eulerian ◽

Fluid Resonance ◽

Resonance Wave ◽

Narrow Gaps

A two-dimensional numerical model is developed to investigate the phenomenon of resonance in narrow gaps. Instead of using commonly used Volume of Fluid method to capture the free surface which is sometimes difficult to capture the geometric properties of the geometrically complicated interface, the free surface is traced by using Arbitrary Lagrangian–Eulerian method. The numerical model is based on the two-dimensional Reynolds-Averaged Navier–Stokes equations. The numerical model is validated against wave propagation in wave flume. Comparisons between the numerical results and available theoretical data show satisfactory agreements. Fluid resonance in narrow gaps of fixed rectangular structures are simulated. Numerical results show that resonance wave height and wave frequency for rectangle boxes with sphenoid corners is larger than for rectangle boxes.

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Bubble Dynamics From Artificial Nucleation Sites During Subcooled Pool Boiling

ASME 2009 Second International Conference on Micro/Nanoscale Heat and Mass Transfer, Volume 3 ◽

10.1115/mnhmt2009-18242 ◽

2009 ◽

Author(s):

Xipeng Lin ◽

David M. Christopher ◽

Yanshen Li ◽

Hui Li

Keyword(s):

High Speed ◽

Bubble Dynamics ◽

Stokes Equations ◽

Liquid Pool ◽

Numerical Results ◽

Bottom Surface ◽

Heating Rates ◽

Bubble Generation ◽

Vof Model ◽

Nucleation Sites

The bubble dynamics of ethanol vapor bubbles growing, coalescing and condensing in a subcooled ethanol liquid pool were investigated experimentally and numerically for a range of subcoolings and heating rates. The bubbles were generated from an artificial pair of nucleation sites made of microscale tubes mounted flush with the bottom surface of the liquid pool with the vapor supplied by a vapor generator. Observations of the bubble generation with a high speed camera show the various coalescence modes with no coalescence at low heating rates and high subcoolings and horizontal and/or vertical coalescence depending on the heating rate and subcooling. At very low subcoolings, the bubbles grew quite large with various types of coalescence. The numerical results using solutions of the Navier-Stokes equations with the VOF model and using a simplified one dimensional model also describe the bubble dynamics and the conditions for coalescence. The numerical results suggest that the condensation rate at the interface is probably much higher than predicted by the model due to significant convection in the liquid pool or due to significant disturbance of the interface by the vapor jet entering the bubble.

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A Three-Dimensional Numerical Model with an L-Type Wave-Maker System for Water Wave Simulations by the Moving Boundary Method

Water ◽

10.3390/w12010161 ◽

2020 ◽

Vol 12 (1) ◽

pp. 161 ◽

Cited By ~ 3

Author(s):

Wei Jia ◽

Shuxue Liu ◽

Jinxuan Li ◽

Yuping Fan

Keyword(s):

Numerical Model ◽

Water Waves ◽

Moving Boundary ◽

Stokes Equations ◽

Three Dimensional ◽

Irregular Waves ◽

Wave Tank ◽

Type Wave ◽

Boundary Method ◽

Wave Maker

A three-dimensional numerical wave tank was developed based on Reynolds averaged Navier–Stokes equations and the volume of fluid method. The moving boundary method is adopted in this model to generate water waves. Piston-type wave-makers are mimicked for the total replication of the physical wave tank conditions. Two-dimensional regular and irregular waves are simulated, with the capability to trigger the active wave absorption algorithm. The two-sided wave-maker system with L-type arrangement is adopted in this model to expand the effective wave areas for three-dimensional waves. Oblique regular waves and multidirectional random waves are simulated, yielding a good agreement with theoretical solutions. The results indicate that this numerical model is an effective tool to provide finer details or complement data unavailable due to the physical setting of a tank experiment.

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Numerical Study of Local Scour around a Submarine Pipeline with a Spoiler Using a Symmetry Boundary Condition

Symmetry ◽

10.3390/sym13101847 ◽

2021 ◽

Vol 13 (10) ◽

pp. 1847

Author(s):

Chuan Zhou ◽

Jianhua Li ◽

Jun Wang ◽

Guoqiang Tang

Keyword(s):

Numerical Model ◽

Stokes Equations ◽

Numerical Study ◽

Lift Coefficient ◽

Numerical Results ◽

Local Scour ◽

Navier Stokes ◽

Scour Depth ◽

Submarine Pipeline ◽

The Mean

A two-dimensional numerical model for solving the Navier–Stokes equations was developed to investigate the local scour around a submarine pipeline with a spoiler. Both the suspended load and the bed load were considered in the present numerical model. The focus of the present study is to investigate the effects of the spoiler length on the hydrodynamic forces on the pipeline and the spoiler as well as the local scour around the submarine pipeline. The corresponding numerical results show that the mean drag coefficients of the pipeline and the spoiler increase with the increase of the spoiler length. As for the mean lift coefficient, a general decreasing trend with the increasing spoiler length is observed for the pipeline. However, the mean lift coefficient of the spoiler first increases and then decreases with the increasing spoiler length. In addition, it is found that a larger spoiler length leads to a deeper scour depth, and an empirical equation was proposed for predicting the non-dimensional scour depth of submarine pipelines with non-dimensional spoiler length based on the numerical results.

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The Numerical Modeling of Coupled Motions of a Moored Floating Body in Waves

Water ◽

10.3390/w10121748 ◽

2018 ◽

Vol 10 (12) ◽

pp. 1748 ◽

Cited By ~ 3

Author(s):

Lin Cheng ◽

Pengzhi Lin

Keyword(s):

Numerical Model ◽

Water Waves ◽

Three Dimensional ◽

Numerical Results ◽

Floating Body ◽

Mooring Line ◽

Floating Structure ◽

Structure Interaction ◽

Coupling Procedure ◽

Boundary Force

Nonlinear interactions between water waves and a moored floating body are investigated using the virtual boundary force (VBF) method. The paper first introduces an in-house three-dimensional viscous incompressible flow model (NEWTANK), which is used to simulate wave-floating structure interaction by using the VBF method. Then the coupling procedure between the mooring line model and the floater model is described. Some validation cases of the developed model, including the motions of a free-floating box in two different water waves, are presented. The present numerical results will be compared with the available experimental data and other numerical results from the published literature. After that, the validity of the mooring line in the numerical model is simulated by simulating the motions of a floating box in still water. Finally, the verified model is applied to analyze the wave-induced motions of a catenary moored floating structure, investigating the motion responses and mooring forces responses. The numerical results agree well with the experimental measurements on the whole. This indicates that the present numerical model can correctly capture the main features of the wave-moored floating structure interaction.

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High-Speed Bird Impact Analysis of Aircraft Windshield by Using a Nonlinear Viscoelastic Model

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.290.85 ◽

2013 ◽

Vol 290 ◽

pp. 85-90 ◽

Cited By ~ 2

Author(s):

Ahmed Uzair ◽

Jun Wang ◽

Ying Jie Xu ◽

Wei Hong Zhang

Keyword(s):

Numerical Model ◽

High Speed ◽

Impact Analysis ◽

Viscoelastic Model ◽

Numerical Results ◽

Tensile Failure ◽

Explicit Finite Element ◽

Impact Location ◽

Nonlinear Viscoelastic ◽

Bird Impact

In this study, a numerical model was established to predict the dynamic response of PMMA based polymeric aircraft windshield against high speed bird impact. A detailed nonlinear viscoelastic constitutive model with tensile failure criterion was used to predict the damage and failure of windshield structure. The numerical model was implemented by employing user defined material subroutine (UMAT) in explicit finite element (FE) solver LS-DYNA 3D. Numerical results were validated against experimental data and further investigations were carried out to study the influence of increased bird velocity and impact location on windshield. On the basis of numerical results, the limiting bird velocity and critical impact location on windshield were determined. The study will help to optimize the design of windshields against high speed bird strikes.

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Effects of stator splitter blades on aerodynamic performance of a single-stage transonic axial compressor

JOURNAL OF MECHANICAL ENGINEERING AND SCIENCES ◽

10.15282/jmes.14.4.2020.05.0579 ◽

2020 ◽

Vol 14 (4) ◽

pp. 7369-7378

Author(s):

Ky-Quang Pham ◽

Xuan-Truong Le ◽

Cong-Truong Dinh

Keyword(s):

Stokes Equations ◽

Three Dimensional ◽

Axial Compressor ◽

Aerodynamic Performance ◽

Numerical Results ◽

Single Stage ◽

Navier Stokes ◽

Navier Stokes Equations ◽

Operating Stability ◽

Length Coverage

Splitter blades located between stator blades in a single-stage axial compressor were proposed and investigated in this work to find their effects on aerodynamic performance and operating stability. Aerodynamic performance of the compressor was evaluated using three-dimensional Reynolds-averaged Navier-Stokes equations using the k-e turbulence model with a scalable wall function. The numerical results for the typical performance parameters without stator splitter blades were validated in comparison with experimental data. The numerical results of a parametric study using four geometric parameters (chord length, coverage angle, height and position) of the stator splitter blades showed that the operational stability of the single-stage axial compressor enhances remarkably using the stator splitter blades. The splitters were effective in suppressing flow separation in the stator domain of the compressor at near-stall condition which affects considerably the aerodynamic performance of the compressor.

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