Simulations of an Air-Ventilated Strut Crossing Water Surface at Variable Yaw Angles

2018 ◽  
Author(s):  
Konstantin I. Matveev ◽  
Miles P. Wheeler ◽  
Tao Xing
Keyword(s):  
Water Surface ◽  
Free Water ◽  
Suction Side ◽  
Complex Flow ◽  
Air Ventilation ◽  
History Of ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations ◽  
Lift Control ◽  
Good Agreement

Hydrodynamic devices intended to produce lift, control actions, or propulsion can be prone to air ventilation when operating near the free water surface. The atmospheric air may propagate to the low-pressure zones around these devices located under the nominal water level. This often leads to performance degradation of hydrodynamic systems. Modeling of air-ventilated flows is challenging due to complex flow nature and many factors in play. In this study, the computational fluid dynamics simulations are carried out for a surface-piercing strut at different yaw angles. At small yaw angles, the strut underwater surfaces remain wetted, whereas at large yaw and sufficiently high Froude numbers the suction side becomes air ventilated. At the intermediate yaw angles, both wetted and ventilated flow regimes are possible, and the existence of a specific state depends on the history of the process. The present computational results demonstrate good agreement with available experimental data.

Numerical Simulation using RANS-based Tools for America’s Cup Design

2003 ◽  
Author(s):  
Geoff Cowles ◽  
Nicola Parolini ◽  
Mark L. Sawley
Keyword(s):  
Design Process ◽  
Water Surface ◽  
Navier Stokes ◽  
Computational Fluid Dynamics Simulations ◽  
America’S Cup ◽  
Dynamics Simulations ◽  
École Polytechnique ◽  
Cup Design ◽  
Cup Drawing

The application of Computational Fluid Dynamics simulations based on the Reynolds Averaged Navier- Stokes (RANS) equations to the design of sailing yachts is becoming more commonplace, particularly for the America's Cup. Drawing on the experience of the Ecole Polytechnique Fédérale de Lausanne as Official Scientific Advisor to the Alinghi Challenge for the America’s Cup 2003, the role of RANS-based codes in the yacht design process is discussed. The strategy for simulating the hydrodynamic flow around the boat appendages is presented. Two different numerical methods for the simulation of wave generation on the water surface are compared. In addition, the aerodynamic flow around different sail configurations is investigated. The benefits to the design process as well as its limitations are discussed. Practical matters, such as manpower and computational requirements, are also considered.

Experimental and Numerical Investigation on the Effects of the Seeding Properties on LDA Measurements

2005 ◽  
Vol 127 (3) ◽  
pp. 514-522 ◽  
Author(s):  
Angelo Algieri ◽  
Sergio Bova ◽  
Carmine De Bartolo
Keyword(s):  
Particle Size ◽  
High Performance ◽  
Laser Doppler Anemometry ◽  
Two Phase ◽  
Large Particles ◽  
Computational Fluid Dynamics Simulations ◽  
Influence Measurement ◽  
Dynamics Simulations ◽  
Commercial Device ◽  
Good Agreement

The characteristics of the seeding particles, which are necessary to implement the laser Doppler anemometry (LDA) technique, may significantly influence measurement accuracy. LDA data were taken on a steady-flow rig, at the entrance of the trumpet of the intake system of a high-performance engine head. Five sets of measurements were carried out using different seeding particles: samples of micro-balloons sieved to give three different size ranges (25–63μm,90–200μm, and standard as received from the manufacturer 1–200μm), smoke from a “home-made” sawdust burner (particle size ⩽1μm), and fog from a commercial device (particle size around 1μm). The LDA data were compared with the results of two-phase computational fluid dynamics simulations. The comparison showed a very good agreement between the experimental and numerical results and confirmed that LDA measurements with particle dimensions in the order of 1μm or less represent the actual gas velocity. On the contrary, quite large particles, which are often used because of their cost and cleanliness advantages, introduce non-negligible errors.

scholarly journals 3-D numerical simulation of the tidal circulation in the Gulf of Tonkin, Vietnam

2001 ◽  
Vol 23 (2) ◽  
pp. 116-128
Author(s):  
Phan Ngoc Vinh ◽  
Nguyen Kim Dan
Keyword(s):  
Numerical Simulation ◽  
Water Surface ◽  
Bottom Topography ◽  
Free Water ◽  
System Transformation ◽  
Tidal Circulation ◽  
Turbulence Mixing ◽  
Gulf Of Tonkin ◽  
Quang Ninh ◽  
Good Agreement

The purpose of this paper is to present 3-D numerical simulation of the tidal circulation in the Gulf of Tonkin. A sigma-coordinate system transformation is used to make possible a total fitting between the computing point-grid and the bottom topography as well as the free water surface. A turbulence-closure sub-model K-L which permits the parameterization of the turbulence mixing is also included. The studied domain, the whole Gulf of Tonkin, extends from the coastal zone of Quang-Ninh into Thua Thien Hue province and as far as Hai-Nam (China) island seawards. The model have been calibrated and verified by the observed data at six different stations for a three and seven-day periods. The results are in good agreement with the observed data. The kinetic energy distribution was considered.

Finite Element Simulations and Experimental Investigations of Simple 2-D Geometries in Slamming

2008 ◽  
Author(s):  
Adrian Constantinescu ◽  
Alain Neme ◽  
Nicolas Jacques ◽  
Philippe Rigo
Keyword(s):  
Finite Element ◽  
Water Surface ◽  
Free Water ◽  
Experimental Tests ◽  
Experimental Investigations ◽  
Convergence Criterion ◽  
Numerical Work ◽  
Fluid Structure ◽  
The Impact ◽  
Good Agreement

This paper presents a numerical and experimental study of fluid structure interaction during the impact of a solid body on a water surface. The main request is the modeling of the slamming forces acting on the ship structure in severe sea conditions. The numerical work uses the finite element modeling of a structure impact with free water surface. The first analysis use the commercial finite element code ABAQUS/Standard and combines the assumption of small displacements for the ideal fluid and the solid with an asymptotic formulation for accurate pressure evaluation on the boundary of the wet surface. For deformable strickers, two methods are developed. The first method employs a weak fluid-structure coupling. The second method, more accurate, uses an implicit fluid-structure coupling using a convergence criterion. The second analysis is represented by the simulations of slamming with ABAQUS/Explicit. The simulation uses a viscous, compressible fluid and a soft-exponential law to manage the contact between fluid and solid. The results in term of pressure and total effort applied to the rigid structure are in good agreement with first numerical results and especially with the FLUENT CFD. In order to validate the numerical methods, slamming experimental tests were carried out with a new hydraulic shock press at the ENSIETA laboratory.

Numerical Simulation of Flow over a Spillway with Turbulence Model

2011 ◽  
Vol 90-93 ◽  
pp. 2511-2515
Author(s):  
Chuan Qi Li ◽  
Jie Gong ◽  
Xiang Fu Li
Keyword(s):  
Turbulence Model ◽  
Water Surface ◽  
Three Dimensional ◽  
Free Water ◽  
Coupling Scheme ◽  
Volume Of Fluid Method ◽  
Experiment Data ◽  
Three Dimensional Flow ◽  
Simulation Results ◽  
Good Agreement

In this paper, the Standard k- ε equation turbulence model was used to simulate three-dimensional flow over a spillway. The volume of fluid method (VOF) was introduced into the iteration of calculation to solve the free water surface, and segregated solver was used with the PISO pressure-velocity coupling scheme. The free surface, the magnitude and distribution of the velocity, the pressure on the spillway surface and so on were obtained. The simulation results were in good agreement with the experiment data.

scholarly journals Effects of scale and Froude number on the hydraulics of waste stabilization ponds

2017 ◽  
Vol 77 (1) ◽  
pp. 239-247
Author(s):  
Isabela De Luna Vieira ◽  
Jhonatan Barbosa Da Silva ◽  
Carlos Nobuyoshi Ide ◽  
Johannes Gérson Janzen
Keyword(s):  
Froude Number ◽  
Reynolds Numbers ◽  
Transport Processes ◽  
Tracer Transport ◽  
Waste Stabilization Ponds ◽  
Stabilization Ponds ◽  
Waste Stabilization ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations ◽  
Good Agreement

Abstract This paper presents the findings from a series of computational fluid dynamics simulations to estimate the effect of scale and Froude number on hydraulic performance and effluent pollutant fraction of scaled waste stabilization ponds designed using Froude similarity. Prior to its application, the model was verified by comparing the computational and experimental results of a model scaled pond, showing good agreement and confirming that the model accurately reproduces the hydrodynamics and tracer transport processes. Our results showed that the scale and the interaction between scale and Froude number has an effect on the hydraulics of ponds. At 1:5 scale, the increase of scale increased short-circuiting and decreased mixing. Furthermore, at 1:10 scale, the increase of scale decreased the effluent pollutant fraction. Since the Reynolds effect cannot be ignored, a ratio of Reynolds and Froude numbers was suggested to predict the effluent pollutant fraction for flows with different Reynolds numbers.

scholarly journals Considerations for the design of bottom intake systems

2017 ◽  
Vol 20 (1) ◽  
pp. 232-245 ◽  
Author(s):  
José M. Carrillo ◽  
Luis G. Castillo ◽  
Juan T. García ◽  
Álvaro Sordo-Ward
Keyword(s):  
Numerical Models ◽  
Turbulence Models ◽  
Discharge Coefficients ◽  
Ansys Cfx ◽  
Laboratory Results ◽  
Computational Fluid Dynamics Simulations ◽  
The Many ◽  
Dynamics Simulations ◽  
Laboratory Experiences ◽  
Good Agreement

Abstract Knowing the scarcity of water in the southeast of Spain and how the rain occurs, we considered the design of intake systems in ephemeral riverbeds in order to try to capture part of the runoff flow. The intake systems generally consist of a rack located in the bottom of a river channel, so that the water collected passes down the rack and leads to the side channel. This behaviour has been studied in the laboratory by several researchers. However, due to the many effects that occur on the bars, it is not possible to analyse the whole problem of characterization with traditional methodologies. For instance, the wetted rack length necessary to collect a required flow presents important differences depending on what each author has considered relevant. Computational fluid dynamics simulations have been done to improve the knowledge of the hydraulic phenomenon observed in different laboratory experiences, for which we have previously calibrated the numerical models using laboratory results. The ANSYS CFX code was selected. Several two-equation turbulence models have been considered. The results show differences smaller than 1% in the wetted rack length, and discharge coefficients also present good agreement.

scholarly journals Numerical Simulations as Tool to Predict Chemical and Radiological Hazardous Diffusion in Case of Nonconventional Events

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
J.-F. Ciparisse ◽  
A. Malizia ◽  
L. A. Poggi ◽  
O. Cenciarelli ◽  
M. Gelfusa ◽  
...  
Keyword(s):  
Industrial Applications ◽  
Gas Release ◽  
Open Environment ◽  
Nuclear Explosive ◽  
Dust Mobilization ◽  
Computational Fluid Dynamics Simulations ◽  
Dangerous Substances ◽  
Dynamics Simulations ◽  
Pure Research ◽  
Good Agreement

CFD (Computational Fluid Dynamics) simulations are widely used nowadays to predict the behaviour of fluids in pure research and in industrial applications. This approach makes it possible to get quantitatively meaningful results, often in good agreement with the experimental ones. The aim of this paper is to show how CFD calculations can help to understand the time evolution of two possible CBRNe (Chemical-Biological-Radiological-Nuclear-explosive) events: (1) hazardous dust mobilization due to the interaction between a jet of air and a metallic powder in case of a LOVA (Loss Of Vacuum Accidents) that is one of the possible accidents that can occur in experimental nuclear fusion plants; (2) toxic gas release in atmosphere. The scenario analysed in the paper has consequences similar to those expected in case of a release of dangerous substances (chemical or radioactive) in enclosed or open environment during nonconventional events (like accidents or man-made or natural disasters).

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