scholarly journals Simulations of Moving Effect of Coastal Vegetation on Tsunami Damping

2016 ◽  
Author(s):  
Ching-Piao Tsai ◽  
Ying-Chi Chen ◽  
Tri Octaviani Sihombing ◽  
Chang Lin
Keyword(s):  
Energy Dissipation ◽  
Kinetic Energy ◽  
Turbulent Kinetic Energy ◽  
Wave Height ◽  
Stokes Equations ◽  
Coastal Vegetation ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Turbulent Closure ◽  
Gmo Model

Abstract. A coupled wave-vegetation simulation is presented for the moving effect of the coastal vegetation on tsunami wave height damping. The problem is idealized by solitary wave propagating on a group of emergent cylinders. The numerical model is based on general Reynolds-averaged Navier-Stokes equations associated with renormalization group turbulent closure model by using volume of fluid technique. The general moving object (GMO) model developed in CFD code Flow-3D is applied to simulate the coupled motion of vegetation with wave dynamically. The damping of wave height and the turbulent kinetic energy dissipation as waves passed over both moving and stationary cylinders are discussed. As comparing with the stationary cylinders, it obtains markedly less wave height damping and turbulent kinetic energy dissipation by the moving cylinders. The result implies that the wave decay by the coastal vegetation might be overestimated if the mangrove vegetation was represented as stationary state.

scholarly journals Simulations of moving effect of coastal vegetation on tsunami damping

2017 ◽  
Vol 17 (5) ◽  
pp. 693-702 ◽  
Author(s):  
Ching-Piao Tsai ◽  
Ying-Chi Chen ◽  
Tri Octaviani Sihombing ◽  
Chang Lin
Keyword(s):  
Kinetic Energy ◽  
Turbulent Kinetic Energy ◽  
Wave Height ◽  
Stokes Equations ◽  
Coastal Vegetation ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Turbulent Closure ◽  
Computational Fluid Dynamics Cfd ◽  
Gmo Model

Abstract. A coupled wave–vegetation simulation is presented for the moving effect of the coastal vegetation on tsunami wave height damping. The problem is idealized by solitary wave propagation on a group of emergent cylinders. The numerical model is based on general Reynolds-averaged Navier–Stokes equations with renormalization group turbulent closure model by using volume of fluid technique. The general moving object (GMO) model developed in computational fluid dynamics (CFD) code Flow-3D is applied to simulate the coupled motion of vegetation with wave dynamically. The damping of wave height and the turbulent kinetic energy along moving and stationary cylinders are discussed. The simulated results show that the damping of wave height and the turbulent kinetic energy by the moving cylinders are clearly less than by the stationary cylinders. The result implies that the wave decay by the coastal vegetation may be overestimated if the vegetation was represented as stationary state.

scholarly journals AUTOMATIC INSERTION OF A TURBULENCE MODEL IN THE FINITE ELEMENT DISCRETIZATION OF THE NAVIER–STOKES EQUATIONS

2009 ◽  
Vol 19 (07) ◽  
pp. 1139-1183 ◽  
Author(s):  
CHRISTINE BERNARDI ◽  
TOMÁS CHACÓN REBOLLO ◽  
FRÉDÉRIC HECHT ◽  
ROGER LEWANDOWSKI
Keyword(s):  
Finite Element ◽  
Kinetic Energy ◽  
Turbulent Kinetic Energy ◽  
Stokes Equations ◽  
A Posteriori Error Estimates ◽  
Navier Stokes ◽  
Mesh Adaptivity ◽  
Finite Element Discretization ◽  
Navier Stokes Equations ◽  
Element Discretization

We consider the finite element discretization of the Navier–Stokes equations locally coupled with the equation for the turbulent kinetic energy through an eddy viscosity. We prove a posteriori error estimates which allow to automatically determine the zone where the turbulent kinetic energy must be inserted in the Navier–Stokes equations and also to perform mesh adaptivity in order to optimize the discretization of these equations. Numerical results confirm the interest of such an approach.

LES of Compressible Turbulent Annular Pipe Flow With a Rotating Wall

2003 ◽  
Author(s):  
Joon Sang Lee ◽  
Xiaofeng Xu ◽  
R. H. Pletcher
Keyword(s):  
Kinetic Energy ◽  
Turbulent Kinetic Energy ◽  
Stokes Equations ◽  
Outer Wall ◽  
Navier Stokes ◽  
Subgrid Scale ◽  
Turbulent Structures ◽  
Navier Stokes Equations ◽  
Rotating Wall ◽  
Annular Pipe

Flow in an annular pipe with and without a wall rotating about its axis was investigated at moderate Reynolds numbers. The compressible filtered Navier-Stokes equations were solved using a second order accurate finite volume method. Low Mach number preconditioning was used to enable the compressible code to work efficiently at low Mach numbers. A dynamic subgrid-scale stress model accounted for the subgrid-scale turbulence. When the outer wall rotated, a significant reduction of turbulent kinetic energy was realized near the rotating wall and the intensity of bursting effects appeared to decrease. This modification of the turbulent structures was related to the vortical structure changes near the rotating wall. It has been observed that the wall vortices were pushed in the direction of rotation and their intensity increased near the non-rotating wall. The consequent effect was to enhance the turbulent kinetic energy and increased the intensity of the heat transfer rate there.

scholarly journals Effect of Baffles on the Sloshing in Road Tankers Carrying LPG: A Comparative Numerical Study

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
J. L. Bautista-Jacobo ◽  
E. Rodríguez-Morales ◽  
J. J. Montes-Rodríguez ◽  
H. Gámez-Cuatzín
Keyword(s):  
Kinetic Energy ◽  
Turbulent Kinetic Energy ◽  
Stokes Equations ◽  
Numerical Study ◽  
Interface Velocity ◽  
Vehicle Control ◽  
Navier Stokes ◽  
Type I ◽  
Type Ii ◽  
Navier Stokes Equations

This work presents a comparative numerical study of the effect of using baffles, and its design, on the behavior of sloshing in a partially filled road tanker carrying LPG. Navier-Stokes equations and standardk-εturbulence model are used to simulate fluid movement; the Volume of Fluid (VOF) method is used to track the liquid-gas interface. Velocity distributions, sloshing stabilization times, and contours of turbulent kinetic energy, which are of high importance in choosing the best design of baffles, are shown. The results show sloshing stabilization times of 22 and 21 s for road tankers with cross-shaped (Type I) and X-shaped (Type II) baffles, respectively, finding lower values of turbulent kinetic energy for Type II design, being, therefore, the best design of baffles for damping of sloshing and vehicle control among studied ones.

scholarly journals A Modified Gas-Kinetic Scheme for Turbulent Flow

2014 ◽  
Vol 16 (1) ◽  
pp. 239-263 ◽  
Author(s):  
Marcello Righi
Keyword(s):  
Boundary Layer ◽  
Shock Wave ◽  
Kinetic Energy ◽  
Turbulent Boundary Layer ◽  
Numerical Scheme ◽  
Stokes Equations ◽  
Kinetic Scheme ◽  
Navier Stokes ◽  
Turbulent Stress ◽  
Navier Stokes Equations

AbstractThe implementation of a turbulent gas-kinetic scheme into a finite-volume RANS solver is put forward, with two turbulent quantities, kinetic energy and dissipation, supplied by an allied turbulence model. This paper shows a number of numerical simulations of flow cases including an interaction between a shock wave and a turbulent boundary layer, where the shock-turbulent boundary layer is captured in a much more convincing way than it normally is by conventional schemes based on the Navier-Stokes equations. In the gas-kinetic scheme, the modeling of turbulence is part of the numerical scheme, which adjusts as a function of the ratio of resolved to unresolved scales of motion. In so doing, the turbulent stress tensor is not constrained into a linear relation with the strain rate. Instead it is modeled on the basis of the analogy between particles and eddies, without any assumptions on the type of turbulence or flow class. Conventional schemes lack multiscale mechanisms: the ratio of unresolved to resolved scales – very much like a degree of rarefaction – is not taken into account even if it may grow to non-negligible values in flow regions such as shocklayers. It is precisely in these flow regions, that the turbulent gas-kinetic scheme seems to provide more accurate predictions than conventional schemes.

scholarly journals Dynamic Response of Base-Isolated Concrete Rectangular Liquid-Storage Structure Under Large Amplitude Sloshing

2017 ◽  
Vol 63 (1) ◽  
pp. 33-45 ◽  
Author(s):  
Xuansheng Cheng ◽  
De Li ◽  
Peijiang Li ◽  
Xiaoyan Zhang ◽  
Guoliang Li
Keyword(s):  
Wave Height ◽  
Large Amplitude ◽  
Stokes Equations ◽  
Seismic Intensity ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Storage Structure ◽  
Liquid Storage ◽  
Rectangular Liquid Storage Structure ◽  
The Mathematical Model

AbstractConsidering concrete nonlinearity, the wave height limit between small and large amplitude sloshing is defined based on the Bernoulli equation. Based on Navier-Stokes equations, the mathematical model of large amplitude sloshing is established for a Concrete Rectangle Liquid-Storage Structure (CRLSS). The results show that the seismic response of a CRLSS increases with the increase of seismic intensity. Under different seismic fortification intensities, the change in trend of wave height, wallboard displacement, and stress are the same, but the amplitudes arc not. The areas of stress concentration appear mainly at the connections between the wallboards, and the connections between the wallboard and the bottom.

Numerical Simulation of Wave Overtopping of Breakwater Armored with Porous Layers and Water-Structure Impaction

2012 ◽  
Vol 226-228 ◽  
pp. 1255-1259
Author(s):  
Zong Liu Huang ◽  
Peng Zhi Lin
Keyword(s):  
Porous Media ◽  
Numerical Model ◽  
Wave Height ◽  
Stokes Equations ◽  
Water Structure ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Wave Overtopping ◽  
Impact Forces ◽  
The Impact

A numerical model has been developed to study wave overtopping of permeable units protected breakwater and water-structure impactions. The numerical model solves the Reynolds Averaged Navier-Stokes equations outside of porous media and solves the spatially averaged Navier-Stokes equations in porous media, respectively. The numerical model is first validated by experimental data. The validated model is then employed to investigate the breaking wave overtopping porous media protected breakwater. The overtopping discharge and impact forces on the structures behind the crown wall in different wave conditions are studied. The increase of wave height brings increasing maximum overtopping discharges and different spatial distribution of water behind the crown wall. The impact forces on the structures are determined by both incident wave height and relative positions of the structures.

Transient inertial hydrodynamic interaction between two identical spheres settling at small Reynolds number

2008 ◽  
Vol 605 ◽  
pp. 263-279 ◽  
Author(s):  
B. U. FELDERHOF
Keyword(s):  
Reynolds Number ◽  
Kinetic Energy ◽  
Relative Motion ◽  
Hydrodynamic Interaction ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Small Reynolds Number ◽  
Navier Stokes Equations ◽  
Small Constant ◽  
Distance Vector

The flow pattern generated by a sphere accelerated from rest by a small constant applied forceshows scaling behaviour at long times, as can be shown from the solution of the linearized Navier–Stokes equations. In the scaling regime the kinetic energy of the flow grows with thesquare root of time. For two distant settling spheres starting from rest the kinetic energy ofthe flow depends on the distance vector between centres; owing to interference of the flowpatterns. It is argued that this leads to relative motion of the two spheres. Thecorresponding interaction energy is calculated explicitly in the scaling regime.

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