Numerical Study of Three Dimensional Effects of Wave Impact on an Oscillating Wave Surge Converter

2015 ◽  
Author(s):  
Yanji Wei ◽  
Frederic Dias
Keyword(s):  
Numerical Study ◽  
Computational Cost ◽  
Three Dimensional ◽  
Wave Interaction ◽  
Diffraction Reflection ◽  
Linear Wave ◽  
Computational Domain ◽  
Wave Impact ◽  
Relaxation Zone ◽  
3D Effects

A CFD model to study the three-dimensional (3D) effects of wave impact on an Oscillating Wave Surge Converter (OWSC) has been demonstrated. Considering the excessive computational cost of CFD models, a relative small computational domain is used here. The velocity at the outside boundary is prescribed based on the classical non-linear wave theory. A relaxation zone is applied to absorb the diffraction/reflection waves by the device to avoid the re-reflection from the outer boundary. This zone is implemented by adding momentum source terms in the N–S equations to blend the near field flow into the far-field wave environment. The simulation of wave interaction with a fixed flap is performed to demonstrate the validity of the relaxation zone. Simulations of wave interaction with an OWSC by various wave conditions (different wave heights and incident angles) are then carried out to understand the 3D effects of the wave impact. The water elevation in the simulation is in agreement with the observations in the experiment. The variation of the pressure distribution indicates that the wave impact is enhanced at the centre of the flap, due to the water re-entry from the sides of the flap into the centre in 3D tests.

scholarly journals Data-Informed Decomposition for Localized Uncertainty Quantification of Dynamical Systems

Vibration ◽  
2020 ◽  
Vol 4 (1) ◽  
pp. 49-63
Author(s):  
Waad Subber ◽  
Sayan Ghosh ◽  
Piyush Pandita ◽  
Yiming Zhang ◽  
Liping Wang
Keyword(s):  
Dynamical Systems ◽  
Computational Cost ◽  
Three Dimensional ◽  
Region Of Interest ◽  
System Response ◽  
Computational Domain ◽  
User Interest ◽  
Numerical Resolution ◽  
Multi Scale ◽  
Operation Conditions

Industrial dynamical systems often exhibit multi-scale responses due to material heterogeneity and complex operation conditions. The smallest length-scale of the systems dynamics controls the numerical resolution required to resolve the embedded physics. In practice however, high numerical resolution is only required in a confined region of the domain where fast dynamics or localized material variability is exhibited, whereas a coarser discretization can be sufficient in the rest majority of the domain. Partitioning the complex dynamical system into smaller easier-to-solve problems based on the localized dynamics and material variability can reduce the overall computational cost. The region of interest can be specified based on the localized features of the solution, user interest, and correlation length of the material properties. For problems where a region of interest is not evident, Bayesian inference can provide a feasible solution. In this work, we employ a Bayesian framework to update the prior knowledge of the localized region of interest using measurements of the system response. Once, the region of interest is identified, the localized uncertainty is propagate forward through the computational domain. We demonstrate our framework using numerical experiments on a three-dimensional elastodynamic problem.

Three-Dimensional CFD Analysis of Meshing Losses in a Spur Gear Pair

2018 ◽  
Author(s):  
T. Fondelli ◽  
D. Massini ◽  
A. Andreini ◽  
B. Facchini ◽  
F. Leonardi
Keyword(s):  
High Speed ◽  
Numerical Study ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Spur Gear ◽  
Computational Domain ◽  
Gear Pair ◽  
Transient Pressure ◽  
Numerical Effort ◽  
Free Environment

The reduction of fluid-dynamic losses in high speed gearing systems is nowadays increasing importance in the design of innovative aircraft propulsion systems, which are particularly focused on improving the propulsive efficiency. Main sources of fluid-dynamic losses in high speed gearing systems are windage losses, inertial losses resulting by impinging oil jets used for jet lubrication and the losses related to the compression and the subsequent expansion of the fluid trapped between gears teeth. The numerical study of the latter is particularly challenging since it faces high speed multiphase flows interacting with moving surfaces, but it paramount for improving knowledge of the fluid behavior in such regions. The current work aims to analyze trapping losses in a gear pair by means of three-dimensional CFD simulations. In order to reduce the numerical effort, an approach for restricting computational domain was defined, thus only a portion of the gear pair geometry was discretized. Transient calculations of a gear pair rotating in an oil-free environment were performed, in the context of conventional eddy viscosity models. Results were compared with experimental data from the open literature in terms of transient pressure within a tooth space, achieving a good agreement. Finally, a strategy for meshing losses calculation was developed and results as a function of rotational speed were discussed.

scholarly journals A Numerical Thermal Analysis of the Heating Process of Large Size Forged Ingots

2018 ◽  
Vol 941 ◽  
pp. 2278-2283
Author(s):  
Nima Bohlooli Arkhazloo ◽  
Farzad Bazdidi-Tehrani ◽  
Morin Jean-Benoit ◽  
Mohammad Jahazi
Keyword(s):  
Heat Transfer ◽  
Heat Treatment ◽  
Conjugate Heat Transfer ◽  
Computational Cost ◽  
Three Dimensional ◽  
Temperature Evolution ◽  
Heating Process ◽  
Computational Domain ◽  
Cfd Model ◽  
Large Size

Simulation and analysis of thermal interactions during heat treatment is of great importance for accurate prediction of temperature evolution of work pieces and consequently controlling the final microstructure and mechanical properties of products. In the present study, a three-dimensional CFD model was employed to predict the heating process of large size forged ingots inside an industrial gas-fired heat treatment furnace. One-ninth section of a loaded furnace, including details such as fixing bars and high-momentum cup burners, was employed as the computational domain. The simulations were conducted using the ANSYS-FLUENT commercial CFD package. The k-ε, P-1 and Probability Density Function (PDF) in the non-premix combustion, as low computational cost numerical approaches were employed to simulate the turbulent fluid flow, thermal radiation, combustion and conjugate heat transfer inside the furnace. Temperature measurement at different locations of the forged ingot surfaces were used to validate the transient numerical simulations. Good agreement was obtained between the predictions of the CFD model and the experimental measurements, demonstrating the reliability of the proposed approach and application of the model for process optimization purposes. Detailed analysis of conjugate heat transfer together with the turbulent combustion showed that the temperature evolution of the product was significantly dependant on the furnace geometry and the severity of turbulent flow structures in the furnace.

On the three-dimensional internal waves excited by topography in the flow of a stratified fluid

1994 ◽  
Vol 263 ◽  
pp. 293-318 ◽  
Author(s):  
Hideshi Hanazaki
Keyword(s):  
Internal Waves ◽  
Numerical Study ◽  
Mach Reflection ◽  
Three Dimensional ◽  
Stratified Fluid ◽  
Linear Wave ◽  
Kp Equation ◽  
Subcritical Flow ◽  
Boussinesq Fluid ◽  
Upstream Waves

A numerical study of the three-dimensional internal waves excited by topography in the flow of a stratified fluid is described. In the resonant flow of a nearly two-layer fluid, it is found that the time-development of the nonlinearly excited waves agrees qualitatively with the solution of the forced KP equation or the forced extended KP equation. In this case, the upstream-advancing solitary waves become asymptotically straight crested because of abnormal reflection at the sidewall similar to Mach reflection. The same phenomenon also occurs in the subcritical flow of a nearly two-layer fluid. However, in the subcritical flow of a linearly stratified Boussinesq fluid, the two-dimensionalization of the upstream waves can be interpreted as the separation of the lateral modes due to the differences in the group velocity of the linear wave, although this does not mean in general that the generation of upstream waves is describable by the linearized equation.

Three-Dimensional Numerical Study on Flames

2009 ◽  
Vol 4 (3) ◽  
Author(s):  
Caimao Luo ◽  
Behdad Moghtaderi ◽  
Eric Kennedy ◽  
Bogdan Dlugogorski
Keyword(s):  
Cfd Simulation ◽  
Numerical Study ◽  
Plug Flow ◽  
Three Dimensional ◽  
Ambient Air ◽  
Combustion Products ◽  
Chemical Kinetic ◽  
Computational Domain ◽  
Counter Flow ◽  
Global Reaction

A three-dimensional (3D) model of a methane-air counter-flow, non-premixed flame with a global reaction step for methane oxidation was developed using computational fluid dynamics (CFD) simulation. A specific computational domain, and relevant thermodynamic and transport data calculated by the chemical kinetic code CHEMKIN, were incorporated into the model. The model was validated by comparing predictions with the spontaneous Raman scattered profiles of major combustion species reported in the literature. The model was employed to carefully examine the self-similarity assumptions normally invoked in simulating counter-flow non-premixed flames. It was found that while most assumptions were strictly satisfied within the jet region for the case of plug flow boundary conditions (B.C.) along the central axis, for the quadratic boundary condition case (corresponding to uniform plug-flow), assumptions were only approximately valid within the jet region. Also, the influence of shroud gas was examined by setting the surrounding gas as air and increasing the shroud gas through widening the shroud gas gap while maintaining a constant shroud gas velocity. Calculations revealed that, the resulting flames for shroud gas gaps greater than half of the jet radius, were totally insulated from mixing with the ambient air. The effect of buoyancy on the flame structures was also studied by comparing contours of the combustion products, temperature and turbulent properties.

Non-Linear Wave Diffraction Around a Moored Ship

2004 ◽  
Author(s):  
J. Zang ◽  
R. Gibson ◽  
P. H. Taylor ◽  
R. Eatock Taylor ◽  
C. Swan
Keyword(s):  
Wave Diffraction ◽  
Scattering Problem ◽  
Wave Interaction ◽  
Wave Structure ◽  
Second Order ◽  
Linear Wave ◽  
Wave Impact ◽  
Non Linear ◽  
Focused Wave ◽  
Run Up

The objective of this research, part of the FP5 REBASDO Programme, is to examine the effects of directional wave spreading on the nonlinear hydrodynamic loads and the wave run-up around the bow of a floating vessel (FPSO) in random seas. In this work, the non-linear wave scattering problem is solved by employing a quadratic boundary element method. An existing scheme (DIFFRACT developed in Oxford) has been extended to deal with uni-directional and directional bi-chromatic input wave systems, calculating second-order wave diffraction under regular waves and focused wave groups. The second order wave interaction with a floating vessel in a unidirectional focused wave group is presented in this paper. Comparison of numerical results and the experimental measurements conducted at Imperial College shows excellent agreement. The second-order free surface components at the bow of the ship are very significant, and cannot be neglected if one requires accurate prediction of the wave-structure interaction; otherwise a major underestimation of the wave impact on the structure could occur.

Numerical Investigation of Tsunami-Like Solitary Wave Interaction with a Seawall

2017 ◽  
Vol 11 (01) ◽  
pp. 1740006 ◽  
Author(s):  
Changbo Jiang ◽  
Xiaojian Liu ◽  
Yu Yao ◽  
Bin Deng ◽  
Jie Chen
Keyword(s):  
Free Surface ◽  
Solitary Waves ◽  
Stokes Equations ◽  
Dynamic Pressure ◽  
Laboratory Data ◽  
Three Dimensional ◽  
Wave Interaction ◽  
Surface Velocity ◽  
Wave Impact ◽  
Two Phase

Seawall is a most commonly used structure in coastal areas to protect the landscape and coastal facilities. The studies of interactions between the tsunami-like solitary waves and the seawalls are relatively rare in the literature. In this study, a three-dimensional numerical model based on OpenFOAM® was developed to investigate the tsunami-like solitary waves propagating over a rectangular seawall. The Navier–Stokes equations for two-phase incompressible flow, combining with methods of [Formula: see text] for turbulence closure and Volume of Fluid (VOF) for tracking the free surface, were solved. Laboratory experiments were performed to measure some of the hydrodynamic feature associated with solitary waves. The model was then validated by the laboratory data, and good agreements were found for free surface, velocity and dynamic pressure around the seawall. Finally, a series of numerical experiments were conducted to analyze the evolution of both wave and flow fields, the overtopping discharge as well as wave pressure (force) around the seawall, special attention is given to the effects of seawall crest width. Our findings will help to improve the understanding in the occurrences of tsunami-induced damages in the vicinity of seawall such as wave impact and local scouring.

scholarly journals Three Dimensional Radiated Water Wave with a Submerged Cylinder in Presence of Circular Plate

2019 ◽  
Vol 9 (1) ◽  
pp. 6665-6670
Keyword(s):  
Separation Of Variables ◽  
Surface Condition ◽  
Three Dimensional ◽  
Wave Interaction ◽  
Wave Theory ◽  
Linear Wave ◽  
Energy Device ◽  
Linear Wave Theory ◽  
Bernoulli’S Equation ◽  
Submerged Cylinder

This work deals with the problem of radiated by wave interaction with a couple of submerged cylinders in water which can be considered as a wave energy device and the problem arising from the rotational motion of submerged upper cylinder which one contains in the device. In this work, we approach theoretically to solve the problem based on the method of separation of variables and we derive the radiated velocity potentials numerically based on linear wave theory and eigenfunctions are introduced for each region by using free surface condition. Then we calculate the hydrodynamic coefficients due to rotational of the upper cylinder by using Bernoulli’s equation of pressure by neglecting the atmospheric pressure and unknown constants are calculate by using matched conditions between the regions Finally, we present all numerical results graphically for different radii of the cylinders

scholarly journals Simulation of Shallow-Water Waves in Coastal Region for Marine Simulator

2009 ◽  
Vol 8 (2) ◽  
pp. 65-70 ◽  
Author(s):  
Yongjin Li ◽  
Yicheng Jin ◽  
Yong Yin ◽  
Helong Shen
Keyword(s):  
Shallow Water ◽  
Water Waves ◽  
Coastal Region ◽  
Wave Interaction ◽  
Sea Surface ◽  
New Order ◽  
Diffraction Reflection ◽  
Linear Wave ◽  
Shallow Water Waves ◽  
Height Fields

This paper presents a new method for simulating shallow-water waves for the marine simulator. Firstly, a sequence of sea surface height fields is achieved by solving 2D Boussinesq type equations. These height fields can exhibit the combined effect of the most shallow-water waves in the coastal region, such as shoaling, refraction, diffraction, reflection and non-linear wave- wave interaction, etc. Secondly, these height fields are synthesized to a new unlimited long sequence by rearranging their order according to their similarity. Finally, the height fields are used as vertex textures sampled by a view-dependent sea surface grid in the new order. Experimental results show that the simulated shallow-water waves have realistic effect with fast rendering speed. It is suitable for the applications of real-time simulation, the marine simulator especially.

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