scholarly journals Coastal wave processes numerical modeling for large valley-type reservoirs

2021 ◽  
Vol 2131 (3) ◽  
pp. 032051
Author(s):  
A I Sukhinov ◽  
V V Sidoryakina ◽  
S V Protsenko
Keyword(s):  
Sediment Transport ◽  
Stokes Equations ◽  
Hydrological Cycle ◽  
Transport Model ◽  
Active Phase ◽  
Navier Stokes ◽  
Bottom Relief ◽  
Wave Processes ◽  
Large Reservoir ◽  
Valley Type

Abstract The problem of modeling sediment transport and wave processes of large valley-type reservoir under non-stationary conditions of the hydrological cycle active phase (spring-autumn period) is considered. Coupled 2D sediment transport model and 3D wave hydrodynamics was considered to describe these processes, which uses the Navier-Stokes equations. The wave hydrodynamics model is applied to large reservoir of the valley type, such as Tsimlyansky reservoir. Detailed numerical experiments were performed taking into account the real coastline geometry and the bottom relief of the Tsimlyansk reservoir southwestern part. The developed complex of models and programs allows to predict reshaping the bottom relief and coastline under various hydrometeorological conditions. The results of modeling can be in demand when planning water management activities in valley-type reservoirs.

scholarly journals EVALUATION OF THE APPLICABILITY OF A TURBULENT WAKE INLET BOUNDARY CONDITION

2017 ◽  
Vol 16 (2) ◽  
pp. 78
Author(s):  
P. A. Soliman ◽  
A. V. de Paula ◽  
A. P. Petry ◽  
S. V. Möller
Keyword(s):  
Stokes Equations ◽  
Transport Model ◽  
Characteristic Length ◽  
Computational Cost ◽  
The Body ◽  
Navier Stokes ◽  
Computational Time ◽  
Flow Forming ◽  
Shear Stress Transport Model ◽  
Grid Convergence Index

With the objective of reducing the computational cost of the iterative processes of aerodynamic components design, tests were carried out to study under what conditions, and with what difference, only part of the calculation domain can be solved using as input information obtained from complete simulations already solved. An experimental study of an airfoil exposed to the wake interference of an upstream airfoil at a Reynolds number of 150,000 was used to verify the solutions of the Reynolds-Averaged Navier-Stokes equations solved applying the k-ω Shear Stress Transport model for turbulence closure. A Grid Convergence Index study was performed to verify if the solution of the equations for the adopted discretization leads to results within the asymptotic range. With the physical coherence of the numerical methodology verified, comparisons between the simulations with the domain comprising the two airfoils and the domain comprising only the downstream airfoil were performed. Computational time reductions in the order of 40% are observed. The differences in the aerodynamic coefficients for the two types of simulation are presented as a function of distances non-dimensionalized by the characteristic length of the body that disturbs the flow forming the wake, showing that the difference between the two methods was inversely proportional to the distance between the two bodies. Behavior that was maintained until a point where the simulation diverges, equivalent to 25% of the characteristic length of the body that generates the wake.

Analysis of an Oscillating Wing in a Power-Extraction Regime Based on the Compressible Reynolds-Averaged Navier-Stokes Equations and the K–ω SST Turbulence Model

2013 ◽  
Author(s):  
M. Sergio Campobasso ◽  
Andreas Piskopakis ◽  
Minghan Yan
Keyword(s):  
Turbulent Flow ◽  
Stokes Equations ◽  
Transport Model ◽  
Extraction Process ◽  
Navier Stokes ◽  
Maximum Efficiency ◽  
Power Extraction ◽  
Shear Stress Transport Model ◽  
Sst Turbulence Model ◽  
Reynolds Averaged Navier Stokes

The aerodynamic performance of an oscillating wing device to extract energy from an oncoming air flow is here investigated by means of time-dependent turbulent flow simulations performed with a compressible Reynolds-averaged Navier-Stokes research solver using the k–ω Shear Stress Transport model. Previous studies of this device have focused primarily on laminar flow regimes, and have shown that the maximum aerodynamic power conversion can achieve values of about 34 %. The comparative analyses of the energy extraction process in a realistic turbulent flow regime and an ideal laminar regime, reported for the first time in this article, highlight that a) substantial differences of the flow aerodynamics exist between the two cases, b) the maximum efficiency of the device in turbulent conditions achieves values of nearly 40 %, and c) further improvement of the efficiency observed in turbulent flow conditions is achievable by optimizing the kinematic characteristics of the device. The theory underlying the implementation of the adopted compressible turbulent flow solver, and several novel algorithmic features associated with its strongly coupled explicit multigrid integration of the flow and turbulence equations, are also presented.

scholarly journals Experimental study and numerical simulation of dam reservoir sediment release

Water SA ◽  
2020 ◽  
Vol 46 (4 October) ◽  
Author(s):  
Marzieh Fadaee ◽  
Mohammad Zounemat-Kermani
Keyword(s):  
Numerical Simulation ◽  
Sediment Transport ◽  
Relative Error ◽  
Water Wave ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Wave Flow ◽  
Navier Stokes Equations ◽  
Water And Sediment ◽  
Three Phase

In this research, experimental and numerical modelling of three-phase air, water, and sediment transport flow, due to the opening of a sluice gate was conducted in two scenarios, i.e., with and without a triangular obstacle. Numerical simulation was conducted using the Navier-Stokes equations with the aid of the volume of fluid method (VOF) to track the free surface of the fluid. For the experimental model, a glass-enclosed flume with 150 × 30 × 50 cm dimensions was used. The experiment was performed for an initial height of the water column at 20 cm and 10 cm sediment column. To evaluate the numerical model's performance, the simulation results were compared with the experimental observations using the average relative error %. The amount of relative error between experimental observations and numerical simulations, for the position and height of the wave flow for the three-phase air, water, and sediment flow, were obtained as 2.64% and 4.51% for the position and height of the water wave, and 2.23% and 2.82% for the position and height of the sediment transport, respectively, for the ‘without obstacle’ scenario, and 3.77% and 5.25% for the position and height of the water wave, and 2% and 7.23% for the position and height of the sediment transport, respectively, for the ‘with obstacle’ scenario. The findings of the study indicate the appropriate performance of the numerical model in the simulation of water and sediment wavefront advance, and also its weakness in the estimation of wave height.

An AGARD Working Group Study of 3D Navier-Stokes Codes Applied to Single Turbomachinery Blade Rows

1998 ◽  
Author(s):  
John Dunham ◽  
Georges Meauzé
Keyword(s):  
Working Group ◽  
Stokes Equations ◽  
Transport Model ◽  
Turbulent Transport ◽  
Turbulence Models ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Wall Flows ◽  
Dimensional Boundary ◽  
Set Up

Computer codes which solve the Reynolds-averaged Navier-Stokes equations are now used by manufacturers to design turbomachines, but there is no consensus among experts about which grids and which turbulence models are good enough to provide a reliable basis for design decisions. The AGARD Propulsion and Energetics Panel set up a Working Group to help to clarify these issues, by analysing predictions (using as wide a range of codes as possible) of two representative but difficult single blade row test cases: NASA Rotor 37 and an annular turbine cascade tested by DLR. This paper summarises the Group’s results and conclusions. Recommendations are made about the type and density of grid, which depend on many factors. Although mixing-length turbulence models give good results for quasi-two-dimensional boundary layers, they are essentially unsuitable for turbomachines with their complex end wall flows; it is essential to adopt some kind of turbulent transport model.

scholarly journals Parallel algorithms for solving the problem of coastal bottom relief dynamics

2020 ◽  
pp. 196-206
Author(s):  
А.И. Сухинов ◽  
А.Е. Чистяков ◽  
Е.А. Проценко ◽  
В.В. Сидорякина ◽  
C.B. Проценко
Keyword(s):  
Sediment Transport ◽  
Parallel Algorithms ◽  
Stokes Equations ◽  
Water Environment ◽  
Continuous Model ◽  
State Equation ◽  
Navier Stokes ◽  
Coastal Zones ◽  
Navier Stokes Equations ◽  
Bottom Deformation

Предложена нестационарная 2D-модель транспорта донных отложений в прибрежной зоне мелководных водоемов, дополненная уравнениями Навье–Стокса, неразрывности и состояния водной среды. Дискретная модель транспорта наносов получена в результате аппроксимации соответствующей линеаризованной непрерывной модели. Поскольку задачи прогнозирования транспорта наносов требуют решения в реальном или ускоренном масштабах времени, на сетках, включающих 106–109 узлов, необходима разработка параллельных алгоритмов задач гидродинамики на системах с массовым параллелизмом. Представлены результаты работы созданного эффективного программного обеспечения для выполнения гидродинамических вычислительных экспериментов, позволяющие проводить численное моделирование деформации дна в прибрежной зоне водоема. Приведены результаты численных экспериментов. A nonstationary 2D model of bottom sediment transport in the coastal zones of shallow water reservoirs is supplemented with the Navier–Stokes equations, the continuity equation, and the state equation of the water environment. A discrete model of sediment transport is obtained by approximating the corresponding linearized continuous model. Since the problems of predicting sediment transport need to be solved in real or accelerated time scales, parallel algorithms for hydrodynamic problems on systems with mass parallelism should be developed on grids with 106–109 nodes. The paper contains the results obtained by an efficient software implemented to perform hydrodynamic computational experiments that allow the numerical modeling of bottom deformation in the coastal zones of reservoir. The results of numerical experiments are discussed.

2D multi-layer hydrodynamic and sediment transport modelling in a tidal estuary

2020 ◽  
Author(s):  
Kai-Yi Bai ◽  
Jiing-Yun You
Keyword(s):  
Sediment Transport ◽  
Shallow Water ◽  
Finite Volume ◽  
Stokes Equations ◽  
Transport Model ◽  
Three Dimensional ◽  
Sediment Concentration ◽  
Computational Domain ◽  
Operation Rules ◽  
Sediment Transport Model

<p>This study developed a multi-layer hydrodynamic and sediment transport model for simulating tides and the estuarine flows. The flow circulation in an estuary shows complicated mixing and stratification patterns due to the combined effects from currents and tides. This kind of issues becomes more important in Taiwan in line with the more and more frequent sediment flushing operation which led to high sediment concentration flow at the estuary. In some applications,  three-dimensional (3D) models solving full Navier-Stokes equations were used. However, the extremely high computational cost, especially for the large-scale environmental problems, is always a serious concern. In the past years, continuous efforts have been devoted to the development of efficient quasi-three-dimensional models under hydrostatic and Boussinesq assumptions. Following the same state-of-the-art modelling strategy, this study develops a multi-layer shallow-water and sediment transport model with finite volume method. In this model, a terrain following coordinate with high local resolution is used to vertically divide the computational domain into multiple layers to better addressing bottom topography and velocity profile. Our model is rigorously validated against several benchmark cases including winddriven circulation, subcritical flow over a hump, tidal wave propagation, and sediment transport. The grid convergence test and accuracy both are in good agreement with analytical solutions. Subsequently, the model is applied to investigate the estuary dynamics and sediment transport under different conditions, e.g., flow discharges, bottom slopes, wind shears and tidal variations. Overall, the results show a relationship between flow conditions and sediment transport. Later, some scenarios for various upstream inflow and sediment concentration will be examined to assess the reservoir operation rules. </p><p><strong>Keywords: shallow water, sediment transport, multi-layer, hydrostatic, Boussinesq Assumption, a finite volume characteristics (FVC) method </strong><br> </p><p><br> <br> <br><br> </p>

Turbulent Unsteady Flow Analysis of Horizontal Axis Wind Turbine Airfoil Aerodynamics Based on the Harmonic Balance Reynolds-Averaged Navier-Stokes Equations

2014 ◽  
Author(s):  
M. Sergio Campobasso ◽  
Fabio Gigante ◽  
Jernej Drofelnik
Keyword(s):  
Wind Turbine ◽  
Time Domain ◽  
Harmonic Balance ◽  
Stokes Equations ◽  
Transport Model ◽  
Flow Analysis ◽  
Horizontal Axis ◽  
Navier Stokes ◽  
Horizontal Axis Wind Turbine ◽  
Reynolds Averaged Navier Stokes

Several horizontal axis wind turbine unsteady flows, such as that associated with the yawed wind regime, are predominantly periodic. Harmonic balance Reynolds-averaged Navier-Stokes solvers can be used to accurately analyze such flows substantially faster than what their time-domain counterparts can do. The paper presents the mathematical and numerical features of a new turbulent harmonic balance Navier-Stokes solver using Menter’s shear stress transport model for the turbulence closure. The effectiveness of the developed technology is demonstrated by using two-dimensional harmonic balance flow simulations to determine the periodic aerodynamic loads acting on a blade section of a 164 m-diameter wind turbine rotor in yawed wind. Presented results highlight that the turbulent harmonic balance solver can compute the sectional hysteresis force cycles more than 10 times faster than its time-domain counterpart, and with an accuracy comparable to that of the time-domain solver.

scholarly journals Numerical Simulation of Scour Depth and Scour Patterns in Front of Vertical-Wall Breakwaters Using OpenFOAM

2020 ◽  
Vol 8 (11) ◽  
pp. 836
Author(s):  
Nikolaos Karagiannis ◽  
Theophanis Karambas ◽  
Christopher Koutitas
Keyword(s):  
Sediment Transport ◽  
Transport Model ◽  
Vertical Wall ◽  
Navier Stokes ◽  
Scour Depth ◽  
Sediment Transport Model ◽  
Coupled Numerical Model ◽  
Equilibrium Profile ◽  
Computational Fluid Dynamics Cfd ◽  
Hydrodynamic Field

An advanced coupled numerical model was developed and implemented in the present work, describing the scour patterns and predicting the scour depth in front of vertical-wall breakwaters. It consists of two independent models, a hydrodynamic Computational Fluid Dynamics (CFD) Reynolds Averaged Navier–Stokes (RANS) model developed on the OpenFOAM (version 2.4.0) toolbox (CFD), describing the wave propagation and the associated hydrodynamic field, and a morphodynamic one (sediment transport model), which was developed in FORTRAN by the authors and yields the updated seabed morphology. The method used here is iterative. The hydrodynamic model is applied for any given initial seabed geometry and wave conditions, resulting in the hydrodynamic field of the flow, which is used as input by the second sediment transport model for the seabed morphology evolution. This process is repeated until the equilibrium profile is achieved. Model results are compared satisfactorily with experimental data for both scour patterns and prediction of scour depth.

scholarly journals Stability of bedforms in laminar flows with free surface: from bars to ripples

2009 ◽  
Vol 642 ◽  
pp. 329-348 ◽  
Author(s):  
O. DEVAUCHELLE ◽  
L. MALVERTI ◽  
É. LAJEUNESSE ◽  
P.-Y. LAGRÉE ◽  
C. JOSSERAND ◽  
...  
Keyword(s):  
Free Surface ◽  
Stability Analysis ◽  
Stokes Equations ◽  
Transport Model ◽  
Bedload Transport ◽  
Laminar Flows ◽  
Three Dimensions ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
The Stability

The present paper is devoted to the formation of sand patterns by laminar flows. It focuses on the rhomboid beach pattern, formed during the backswash. A recent bedload transport model, based on a moving-grains balance, is generalized in three dimensions for viscous flows. The water flow is modelled by the full incompressible Navier–Stokes equations with a free surface. A linear stability analysis then shows the simultaneous existence of two distinct instabilities, namely ripples and bars. The comparison of the bar instability characteristics with laboratory rhomboid patterns indicates that the latter could result from the nonlinear evolution of unstable bars. This result, together with the sensibility of the stability analysis with respect to the parameters of the transport law, suggests that the rhomboid pattern could help improving sediment transport models, so critical to geomorphologists.

scholarly journals Two-level, two-phase model for intense, turbulent sediment transport

2018 ◽  
Vol 839 ◽  
pp. 198-238 ◽  
Author(s):  
Jose M. Gonzalez-Ondina ◽  
Luigi Fraccarollo ◽  
Philip L.-F. Liu
Keyword(s):  
Sediment Transport ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Small Scale ◽  
High Concentration ◽  
Two Phase ◽  
Theoretical Derivation ◽  
Length Scales ◽  
Fluid Turbulence ◽  
Wide Range

The study of sediment transport requires in-depth investigation of the complex effects of sediment particles in fluid turbulence. In this paper we focus on intense sediment transport flows. None of the existing two-phase models in the literature properly replicates the liquid and solid stresses in the near bed region of high concentration of sediment. The reason for this shortcoming is that the physical processes occurring at the length scale of the particle collisions are different from those occurring at larger length scales and therefore, they must be modelled independently. We present here a two-level theoretical derivation of two-phase, Favre averaged Navier–Stokes equations (FANS). This approach treats two levels of energy fluctuations independently, those associated with a granular spatial scale (granular temperature and small-scale fluid turbulence) and those associated with the ensemble average (turbulent kinetic energy for the two phases). Although similar attempts have been made by other researchers, the two level approach ensures that the two relevant length scales are included independently in a more consistent manner. The model is endowed with a semi-empirical formulation for the granular scale fluid turbulence, which is important even in the dense collisional shear layer, as has been recently recognized. As a result of the large and small scale modelling of the liquid and solid fluctuations, predictions are promising to be reliable in a wide range of flow conditions, from collisional to turbulent suspensions. This model has been validated for steady state flows with intense, collisional or mixed collisional–turbulent sediment transport, using various sources of detailed experimental data. It compares well with the experimental results in the whole experimental range of Shields parameters, better than previous models, although at the cost of increased complexity in the equations. Further experiments on turbulent suspensions would be necessary to definitely assess the model capabilities.

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