scholarly journals SPH MODELING OF MEAN VELOCITY CIRCULATION IN A RIP CURRENT SYSTEM

2012 ◽  
Vol 1 (33) ◽  
pp. 37
Author(s):  
Rozita Jalali Farahani ◽  
Robert A. Dalrymple ◽  
Alexis Hérault ◽  
Giuseppe Bilotta
Keyword(s):  
Numerical Model ◽  
Dimensional Space ◽  
Current System ◽  
Three Dimensional ◽  
Rip Current ◽  
Mean Velocity ◽  
Circulation Cell ◽  
Particle Hydrodynamics ◽  
Horizontal Variations ◽  
Wave Induced

A Lagrangian numerical model called Smoothed Particle Hydrodynamics is used to analyze rip current system generated by a single bar and a rip channel. The pattern of the wave-induced circulation cell over the bar, the oppositely-rotating circulation cell on-shore and a strong seaward-directed current in the rip channel is modeled numerically. The mean horizontal variations of rip current system as well as three-dimensional circulations are studied. The results in three-dimensional space reveal the wave-current interaction and flow patterns in different parts of rip channel, bar, and the trough located near shore. For comparison to experimental data, Eulerian nodes are introduced to the numerical model and SPH interpolation over neighboring Lagrangian particles is implemented to find fluid parameters at those specific nodes. This methodology leads to a better understanding of depth-integrated flows and a more accurate comparison of numerical results with experimental results. Model predictions are compared to laboratory measurements of Drønen et al. (2002) and show good agreement, including mean velocity profiles, mean surface elevation and three-dimensional velocity components.

Numerical Simulation of High Speed Single-Grain Cutting Using a Coupled FE-SPH Approach

2013 ◽  
Vol 483 ◽  
pp. 3-8 ◽  
Author(s):  
Rui Dong Shen ◽  
Xiu Mei Wang ◽  
Chun Hui Yang
Keyword(s):  
Numerical Model ◽  
High Speed ◽  
Three Dimensional ◽  
Cutting Speed ◽  
Chip Thickness ◽  
Rake Angle ◽  
High Cutting Speed ◽  
Particle Hydrodynamics ◽  
Single Grain ◽  
Cutting Processes

In this study, to simulate the grinding process for rolled homogeneous armor steel (RHA) 4043, a single-grain cutting process is modeled using a three-dimensional (3-D) numerical model, which is developed using a coupled finite element (FE) - smoothed-particle hydrodynamics (SPH) approach. The proposed numerical model is then employed to investigate the influences of grain negative rake angle (-22°, -31°, and-45°) as well as high and super-high cutting speed ranged from 100 m/s to 260 m/s in the cutting processes. The numerical results show the cutting forces are much lower and the maximum chip thickness is much larger when using a smaller grain negative rake angle.

Three-Dimensional Modeling of Wave-Induced Seabed Response Around a Semi-Buried Pipeline: A Small-Scale Case

2019 ◽  
Vol 142 (2) ◽  
Author(s):  
Jianfeng Zhu ◽  
Hongyi Zhao
Keyword(s):  
Numerical Model ◽  
Three Dimensional ◽  
The Body ◽  
Navier Stokes ◽  
Small Scale ◽  
Buried Pipeline ◽  
Consolidation Process ◽  
Soil Response ◽  
Wave Flume ◽  
Wave Induced

Abstract In this paper, a three-dimensional integrated numerical model for a small-scale case of wave-induced oscillatory soil response around a semi-buried pipeline (PORO-WSSI-PIPE 3D) is proposed. In this model, we combine the Reynolds-averaged Navier–Stokes (RANS) equations for the 3D wave motions and the Biot’s consolidation equations for a porous elastic seabed foundation through pressure continuity at common boundaries, with pipeline being an elastic and impermeable medium. The computational results are validated through comparison with previous analytical solutions and laboratory wave flume tests, obtaining good agreement. Following validation, the numerical model is applied to simulate wave-seabed-pipeline interaction with different obliquities between pipeline and incident wave, varying from 30 deg to 90 deg. Snapshots of wave-seabed-pipeline interaction, as well as dynamic pore pressure distributions at typical locations in the vicinity of a semi-buried pipeline, are obtained and analyzed. The three-dimensional consolidation process of seabed under gravitational forces including the body forces of a pipeline is also discussed.

scholarly journals Three-dimensional numerical model for wave-induced seabed response around mono-pile

2015 ◽  
Vol 11 (6) ◽  
pp. 667-678 ◽  
Author(s):  
Titi Sui ◽  
Chi Zhang ◽  
Yakun Guo ◽  
Jinhai Zheng ◽  
Dongsheng Jeng ◽  
...  
Keyword(s):  
Numerical Model ◽  
Three Dimensional ◽  
Wave Induced

Effects of the Initial Consolidation on the 3D Wave-Induced Seabed Response Around a Pile

2017 ◽  
Author(s):  
Jian Ding ◽  
Titi Sui ◽  
Chi Zhang ◽  
Yuan Li
Keyword(s):  
Numerical Model ◽  
Dynamic Response ◽  
Numerical Simulations ◽  
Normal Stress ◽  
Pile Foundation ◽  
Three Dimensional ◽  
Model Application ◽  
Effective Normal Stress ◽  
Wave Induced ◽  
Simulation Condition

Seabed consolidation state could be seen as the initial simulation condition for numerically simulating wave-induced seabed response. In this study, based on a three dimensional numerical model, effects of initial consolidation state on the 3D wave-induced unsaturated seabed response around mono-pile were investigated. By model application, the consolidation state of seabed around the pile foundation was described. Two common calculation approaches (seabed consolidation is considered or not) for wave-induced seabed response were compared by describing the distributions pattern of soil effective stresses and pore pressures around the pile. Significance of the consolidation state on seabed dynamic response against distances to pile was also carefully addressed. Numerical simulations indicated (1) the initial consolidation significantly increases the vertical effective normal stress in the vicinity of pile, (2) effects of the initial seabed consolidation on the wave-induced seabed response decrease with the increasing distance to the pile. This study suggests the initial consolidation should be considered in assessing the seabed stability for the design of the mono-pile foundation.

scholarly journals ISPH Simulation of Solitary Waves Propagating Over a Bottom-Mounted Barrier With k–ε Turbulence Model

2021 ◽  
Vol 9 ◽  
Author(s):  
Dong Wang ◽  
Sheng Yan ◽  
Chen Chen ◽  
JianGuo Lin ◽  
Xupeng Wang ◽  
...  
Keyword(s):  
Numerical Model ◽  
Turbulence Model ◽  
Flow Separation ◽  
Mean Velocity ◽  
Turbulence Characteristics ◽  
Transmission Coefficients ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Incompressible Smoothed Particle Hydrodynamics ◽  
Good Agreement

Solitary wave propagating over a bottom-mounted barrier is simulated using the Incompressible Smoothed Particle Hydrodynamics (ISPH) method in order to study the generation and transport of turbulence associated with flow separation around submerged structures. For an accurate capture of turbulence characteristics during the wave propagation, rather than employing the standard sub-particle scale (SPS) model, the k-ε turbulence model is coupled with the numerical scheme. The results of the numerical model are compared with experimental data, and good agreement is observed in terms of mean velocity, free surface elevation, vorticity fields and turbulent kinetic energy. The numerical model is then employed to investigate the effects of wave non-linearity and geometrical size of the submerged barrier on the flow separation; and calculate the reflection, dissipation and transmission coefficients to evaluate the importance of energy dissipation due to the generation of vortices. The results of this study show that the developed ISPH method with the k-ε turbulence closure model is capable of reproducing the velocity fields and the turbulence characteristics accurately, and thus can be used to perform predictions of comprehensive hydrodynamics of flow-structure interactions in the urban hydro-environment systems.

scholarly journals A Hybrid Parallel Numerical Model for Wave-Induced Free-Surface Flow

Fluids ◽  
2021 ◽  
Vol 6 (10) ◽  
pp. 350
Author(s):  
Georgios A. Leftheriotis ◽  
Iason A. Chalmoukis ◽  
Guillermo Oyarzun ◽  
Athanassios A. Dimas
Keyword(s):  
Free Surface ◽  
Numerical Model ◽  
Large Scale ◽  
Stokes Equations ◽  
Parallel Implementation ◽  
Three Dimensional ◽  
Free Surface Flow ◽  
Free Surface Flows ◽  
Surface Flow ◽  
Wave Induced

An advanced numerical model is presented for the simulation of wave-induced free-surface flow, utilizing an efficient hybrid parallel implementation. The model is based on the solution of the Navier–Stokes equations using large-eddy simulation of large-scale coastal free-surface flows. The three-dimensional immersed boundary method was used for the enforcement of the no-slip boundary condition on the bed surface. The water-air interface was tracked using the level-set method. The numerical model was effectively validated against laboratory measurements involving wave propagation over a flatbed with an elliptical shoal, whose presence induces combined wave refraction and diffraction phenomena. The parallel implementation of the model enabled the efficient simulation of depth-resolved, wave-induced, three-dimensional, free-surface flow; the model parallel efficiency and strong scaling are quantitatively demonstrated.

Three Dimensional structure and organization of diploid chromosomes by optical section microscopy

1987 ◽  
Vol 45 ◽  
pp. 633-635
Author(s):  
David A. Agard ◽  
Yasushi Hiraoka ◽  
John W. Sedat
Keyword(s):  
Dimensional Space ◽  
Three Dimensional ◽  
Developmental State ◽  
Mitotic Cell ◽  
Biological Properties ◽  
Dimensional Structure ◽  
Specific Gene ◽  
Three Dimensional Structure ◽  
Complementary Techniques ◽  
Dynamic Structures

In an effort to understand the complex relationship between structure and biological function within the nucleus, we have embarked on a program to examine the three-dimensional structure and organization of Drosophila melanogaster embryonic chromosomes. Our overall goal is to determine how DNA and proteins are organized into complex and highly dynamic structures (chromosomes) and how these chromosomes are arranged in three dimensional space within the cell nucleus. Futher, we hope to be able to correlate structual data with such fundamental biological properties as stage in the mitotic cell cycle, developmental state and transcription at specific gene loci.Towards this end, we have been developing methodologies for the three-dimensional analysis of non-crystalline biological specimens using optical and electron microscopy. We feel that the combination of these two complementary techniques allows an unprecedented look at the structural organization of cellular components ranging in size from 100A to 100 microns.

Diffraction contrast of dislocations in icosahedral quasicrystals

1990 ◽  
Vol 48 (4) ◽  
pp. 454-455
Author(s):  
K. Urban ◽  
Z. Zhang ◽  
M. Wollgarten ◽  
D. Gratias
Keyword(s):  
Dimensional Space ◽  
Three Dimensional ◽  
Complete Characterization ◽  
Extinction Condition ◽  
Burgers Vector ◽  
Diffraction Contrast ◽  
Lattice Geometry ◽  
Reference Space ◽  
Icosahedral Quasicrystals ◽  
The One

Recently dislocations have been observed by electron microscopy in the icosahedral quasicrystalline (IQ) phase of Al65Cu20Fe15. These dislocations exhibit diffraction contrast similar to that known for dislocations in conventional crystals. The contrast becomes extinct for certain diffraction vectors g. In the following the basis of electron diffraction contrast of dislocations in the IQ phase is described. Taking account of the six-dimensional nature of the Burgers vector a “strong” and a “weak” extinction condition are found.Dislocations in quasicrystals canot be described on the basis of simple shear or insertion of a lattice plane only. In order to achieve a complete characterization of these dislocations it is advantageous to make use of the one to one correspondence of the lattice geometry in our three-dimensional space (R3) and that in the six-dimensional reference space (R6) where full periodicity is recovered . Therefore the contrast extinction condition has to be written as gpbp + gobo = 0 (1). The diffraction vector g and the Burgers vector b decompose into two vectors gp, bp and go, bo in, respectively, the physical and the orthogonal three-dimensional sub-spaces of R6.

Flavin radicals, conformational sampling and robust design principles in interprotein electron transfer: the trimethylamine dehydrogenase-electron-transferring flavoprotein complex

2004 ◽  
Vol 71 ◽  
pp. 1-14
Author(s):  
David Leys ◽  
Jaswir Basran ◽  
François Talfournier ◽  
Kamaldeep K. Chohan ◽  
Andrew W. Munro ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Kinetic Studies ◽  
Molecular Assembly ◽  
Conformational Sampling ◽  
Trimethylamine Dehydrogenase ◽  
Key Residues ◽  
Electron Transferring Flavoprotein ◽  
Electron Transfer Complex

TMADH (trimethylamine dehydrogenase) is a complex iron-sulphur flavoprotein that forms a soluble electron-transfer complex with ETF (electron-transferring flavoprotein). The mechanism of electron transfer between TMADH and ETF has been studied using stopped-flow kinetic and mutagenesis methods, and more recently by X-ray crystallography. Potentiometric methods have also been used to identify key residues involved in the stabilization of the flavin radical semiquinone species in ETF. These studies have demonstrated a key role for 'conformational sampling' in the electron-transfer complex, facilitated by two-site contact of ETF with TMADH. Exploration of three-dimensional space in the complex allows the FAD of ETF to find conformations compatible with enhanced electronic coupling with the 4Fe-4S centre of TMADH. This mechanism of electron transfer provides for a more robust and accessible design principle for interprotein electron transfer compared with simpler models that invoke the collision of redox partners followed by electron transfer. The structure of the TMADH-ETF complex confirms the role of key residues in electron transfer and molecular assembly, originally suggested from detailed kinetic studies in wild-type and mutant complexes, and from molecular modelling.

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