scholarly journals NUMERICAL STUDY OF NEARSHORE HYDRODYNAMICS UNDER STORM WAVE CONDITIONS IN HUJEONG BEACH, EAST COAST OF KOREA

2018 ◽  
pp. 67
Author(s):  
Yeon S. Chang ◽  
Jong Dae Do ◽  
Kyungmo Ahn ◽  
Jae-Youll Jin
Keyword(s):  
Numerical Model ◽  
East Coast ◽  
Surf Zone ◽  
Numerical Study ◽  
Navier Stokes ◽  
Model Study ◽  
Suspended Sediment Concentrations ◽  
Storm Wave ◽  
Wave Conditions ◽  
The Republic

In this study, we present the results of numerical model study to simulate the hydrodynamic conditions observed in Hujeong Beach in the east coast of the Republic of Kore from December, 2016 to January, 2017 during which several extratropical cyclones hit the area causing extreme wave conditions. Three acoustic instrumentation systems were moored from the coast to a location outside the surf zone where the water depth was ~8m to measure waves, currents and suspended sediment concentrations. For the numerical model, we employed the CADMAS-SURF Raynolds-Averaged Navier-Stokes (RANS) model to generate the wave conditions over the region of the field experiment.

scholarly journals Experimental and Numerical Study on Water Filling and Air Expelling Process in a Pipe with Multiple Air Valves under Water Slow Filling Condition

Water ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2511
Author(s):  
Jintao Liu ◽  
Di Xu ◽  
Shaohui Zhang ◽  
Meijian Bai
Keyword(s):  
Numerical Model ◽  
Stokes Equations ◽  
Numerical Study ◽  
Practical Method ◽  
Navier Stokes ◽  
Physical Processes ◽  
Two Phase ◽  
Saint Venant Equations ◽  
Water Filling ◽  
Air Valve

This paper investigates the physical processes involved in the water filling and air expelling process of a pipe with multiple air valves under water slow filling condition, and develops a fully coupledwater–air two-phase stratified numerical model for simulating the process. In this model, the Saint-Venant equations and the Vertical Average Navier–Stokes equations (VANS) are respectively applied to describe the water and air in pipe, and the air valve model is introduced into the VANS equations of air as the source term. The finite-volume method and implicit dual time-stepping method (IDTS) with two-order accuracy are simultaneously used to solve this numerical model to realize the full coupling between water and air movement. Then, the model is validated by using the experimental data of the pressure evolution in pipe and the air velocity evolution of air valves, which respectively characterize the water filling and air expelling process. The results show that the model performs well in capturing the physical processes, and a reasonable agreement is obtained between numerical and experimental results. This agreement demonstrates that the proposed model in this paper offers a practical method for simulating water filling and air expelling process in a pipe with multiple air valves under water slow filling condition.

Scouring Below Pipelines: The Role of Vorticity and Turbulence

2010 ◽  
Author(s):  
Matteo Mattioli ◽  
Alessandro Mancinelli ◽  
Giuseppina Colicchio ◽  
Maurizio Brocchini
Keyword(s):  
Numerical Model ◽  
Lift Force ◽  
Stokes Equations ◽  
Numerical Study ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Offshore Pipeline ◽  
Temporal Averaging ◽  
Force Components

A numerical study on the turbulence and vorticity of local scour underneath an offshore pipeline placed on a non-cohesive sandy seabed and forced by a steady flow current is presented. The numerical model solves the Navier-Stokes equations using an innovative Level Set technique. The model predicts the behavior of the movable sediments through both drift and lift force components. Mean and turbulent flow quantities were extracted by temporal averaging. Results on the distribution and evolution of turbulent kinetic energy and vorticity will be illustrated at the conference.

scholarly journals MOVABLE-BED MODEL STUDIES OF PERCHED BEACH CONCEPT

1972 ◽  
Vol 1 (13) ◽  
pp. 60
Author(s):  
C.B. Chatham
Keyword(s):  
Three Dimensional ◽  
Normal Wave ◽  
Beach Erosion ◽  
Model Studies ◽  
Model Study ◽  
Wide Range ◽  
Final Design ◽  
Storm Wave ◽  
Wave Conditions ◽  
Movable Bed

Hydraulic model studies were conducted to aid in ascertaining the technical feasibility and optimum design factors of the perched beach concept. Among these were two-dimensional, movable-bed studies to determine an estimate of the amount of sand which would be lost seaward over the submerged toe structure by normal and storm wave action, the optimum elevation of the submerged toe structure, and the length of a stone blanket required to reduce seaward migration of sand to a minimum. The model beach was subjected to test waves until equilibrium was reached for a wide range of wave conditions for both the existing beach and the perched beach. Test results indicate that (a) little or no beachfill material will be lost seaward of the toe structure for normal wave conditions but the larger storm waves may cause erosion of the perched beach, (b) the installation of a stone blanket shoreward of the toe structure will reduce the amount of beach erosion, (c) if the beach fill is extended a sufficient distance seaward, the toe structure serves no useful purpose, and (d) a three-dimensional movable-bed model study is feasible and is necessary to determine the final design features of a perched beach.

Numerical study of the melting and resolidification of the substrate during the impact of a ceramic droplet in a plasma spraying process

2019 ◽  
Vol 88 (2) ◽  
pp. 20901 ◽  
Author(s):  
Mouloud Driouche ◽  
Tahar Rezoug ◽  
Mohammed El Ganaoui
Keyword(s):  
Numerical Model ◽  
Phase Change ◽  
Solid Phase ◽  
Numerical Study ◽  
Solid Substrate ◽  
Navier Stokes ◽  
Droplet Spreading ◽  
Substrate Melting ◽  
Volume Method ◽  
The Impact

The substrate melting can significantly improve the properties of plasma spray coatings. Indeed the adhesion of the projected particles to the substrate can be ameliorated by the substrate melting. In this article, a numerical model is developed to study the dynamics of fluids and heat transfer with liquid/solid phase change during impact of a fully melted alumina particle on an aluminum solid substrate, taking into account of the substrate melting. The model is based on solving the Navier-Stokes and energy equations with liquid / solid phase change. These equations are coupled with the fluid of volume method (VOF), to follow the free surface of the particle during its spreading and solidification. The finite volume method is used to discretize the equations in a 2D axisymmetric domain. A comparison with the published experimental results was carried out to validate this numerical model. Simulations were performed for different initial droplet diameters to study its effect on droplet spreading as well as on substrate melting. It has been observed that the substrate melting begins before the droplet spreads completely; the substrate melting reaches its maximum when the droplet is close to its total solidification. Droplet spreading and substrate melting are more important for large sizes droplets.

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

Symmetry ◽  
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.

scholarly journals ON THE INITIATION OF NEARSHORE MORPHOLOGICAL RHYTHMICITY

2011 ◽  
Vol 1 (32) ◽  
pp. 47
Author(s):  
Matthieu Andreas De Schipper ◽  
Roshanka Ranasinghe ◽  
Ad Reniers ◽  
Marcel Stive
Keyword(s):  
Numerical Model ◽  
Wave Period ◽  
Wave Group ◽  
Initiation Time ◽  
Length Scales ◽  
Long Wave ◽  
Storm Wave ◽  
Wave Conditions

Nearshore rhythmicity is often initiated in the period just after a storm where the subtidal bar is turned alongshore uniform. The initiation time as well as the length scales of the created rhythmicity varies from one storm period to another. Here we show that the post-storm wave conditions are related to the initiation of the morphological rhythmicity. Narrow-banded and long wave period, both proxies for swell waves, are often found to be present priorto the initiation of rhythmicity. Furthermore, numerical model computations illustrate that swell waves induce significantly larger wave group induced velocities on the bar. These findings imply that the arrival of swell waves can initiate and stimulate the nearshore morphological rhythmicity.

scholarly journals Numerical and physical model study of a vertical slot fishway

2014 ◽  
Vol 62 (2) ◽  
pp. 150-159 ◽  
Author(s):  
Martin Bombač ◽  
Gorazd Novak ◽  
Primož Rodič ◽  
Matjaž Četina
Keyword(s):  
Numerical Model ◽  
Eddy Viscosity ◽  
Numerical Study ◽  
Flow Characteristics ◽  
Maximum Velocity ◽  
Energy Dissipation Rate ◽  
Model Study ◽  
Vertical Slot ◽  
Vertical Slot Fishway ◽  
Turbulent Models

Abstract This paper presents the results of an experimental and numerical study of a vertical slot fishway (VSF). A 2-D depth-averaged shallow water numerical model PCFLOW2D coupled with three different turbulent models (constant eddy viscosity, Smagorinsky and k - ε) was used. A detailed analysis of numerical parameters needed for a correct simulation of the phenomenon was carried out. Besides the velocity field, attention was paid to important hydraulic parameters such as maximum velocity in the slot region and energy dissipation rate ε in order to evaluate the performance of VSF. A scaled physical hydraulic model was built to ensure reliable experimental data for the validation of the numerical model. Simulations of variant configurations of VSF showed that even small changes in geometry can produce more fishfriendly flow characteristics in pools. The present study indicates that the PCFLOW2D program is an appropriate tool to meet the main demands of the VSF design.

scholarly journals Numerical Study of Solitary Wave Interaction with a Submerged Semicircular Cylinder

2019 ◽  
Vol 2019 ◽  
pp. 1-15
Author(s):  
Qiaoling Ji ◽  
Yu Wang ◽  
Guowei Zhang
Keyword(s):  
Numerical Model ◽  
Solitary Wave ◽  
Stokes Equations ◽  
Numerical Study ◽  
Wave Interaction ◽  
Wave Structure ◽  
Navier Stokes ◽  
Constrained Interpolation ◽  
Navier Stokes Equations ◽  
Model Combining

The propagation on submerged structures of solitary wave, as a typical nonlinear wave, has guiding significance for the design and operation of coastal engineering. This paper presents a numerical model based on Navier-Stokes equations to study the interaction of the solitary wave with a submerged semicircular cylinder. A multiphase method is utilized to deal with water and air phase. The model uses the CIP (Constrained Interpolation Profile) method to solve the convection term of the Navier-Stokes equations and the THINC (Tangent of Hyperbola for Interface Capturing) scheme to capture the free surface. Three representative cases different in relative solitary wave height and structure size are simulated and analyzed by this model. By comparing the surface elevations at wave gauges with the experimental data and the documented numerical results, the present model is verified. Then, the wave pressure field around the submerged semicircular cylinder is presented and analyzed. At last, the velocity and vorticity fields are demonstrated to elucidate the characteristics of wave breaking, flow separation, and vortex generation and evolution during the wave-structure interaction. This work presents the fact that this numerical model combining the CIP and THINC methods has the ability to give a comprehensive comprehension of the flow around the structure during the nonlinear interaction of the solitary wave with a submerged structure.

scholarly journals Two-Dimensional Numerical Study of Seabed Response around a Buried Pipeline under Wave and Current Loading

2019 ◽  
Vol 7 (3) ◽  
pp. 66 ◽  
Author(s):  
Cynthia Foo ◽  
Chencong Liao ◽  
Jinjian Chen
Keyword(s):  
Numerical Model ◽  
Pore Pressure ◽  
Numerical Study ◽  
Current Model ◽  
Navier Stokes ◽  
Buried Pipeline ◽  
Soil Permeability ◽  
Biot’S Equation ◽  
Current Loading ◽  
Wave Induced

The evaluation of the wave-induced seabed response around a buried pipeline has been widely studied. However, the analysis of seabed response around marine structures under the wave and current loadings are still limited. In this paper, an integrated numerical model is proposed to examine the wave and current-induced pore pressure generation, for instance, oscillatory and residual pore pressure, around a buried pipeline. The present wave–current model is based on the Reynolds-Averaged Navier–Stokes (RANS) equation with k - ε turbulence while Biot’s equation is adopted to govern the seabed model. Based on this numerical model, it is found that wave characteristics (i.e., wave period), current velocity and seabed characteristics such as soil permeability, relative density, and shear modulus have a significant effect on the generation of pore pressure around the buried pipeline.

scholarly journals Numerical Study of Highly Viscous Fluid Sloshing in the Real-Scale Membrane-Type Tank

Energies ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 4244 ◽  
Author(s):  
Shuo Mi ◽  
Zongliu Huang ◽  
Xin Jin ◽  
Mahdi Tabatabaei Malazi ◽  
Mingming Liu
Keyword(s):  
Free Surface ◽  
Numerical Model ◽  
Stokes Equations ◽  
Numerical Study ◽  
Full Scale ◽  
Navier Stokes ◽  
Fast Fourier Transformation ◽  
Two Phase ◽  
Wide Range ◽  
Membrane Type

The highly viscous liquid (glycerin) sloshing is investigated numerically in this study. The full-scale membrane-type tank is considered. The numerical investigation is performed by applying a two-phase numerical model based on the spatially averaged Navier-Stokes equations. Firstly, the numerical model is validated against the available numerical model and a self-conducted experiment then is applied to systematically investigate the full-scale sloshing. In this study, two filling levels (50% and 70% of the tank height) are considered. The fluid kinematic viscosity is fixed at a value being 6.0 × 10−5 m2/s with comparative value to that of the crude oil. A wide range of forcing periods varying from 8.0 s to 12.0 s are used to identify the response process of pressures as well as free surface displacements. The pressures are analyzed along with breaking free surface snapshots and corresponding pressure distributions. The slamming effects are also demonstrated. Finally, the frequency response is further identified by the fast Fourier transformation technology.

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