The Experts below are selected from a list of 34698 Experts worldwide ranked by ideXlab platform
Catherine Gorle - One of the best experts on this subject based on the ideXlab platform.
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quantifying inflow and rans turbulence model form uncertainties for Wind Engineering flows
Journal of Wind Engineering and Industrial Aerodynamics, 2015Co-Authors: Catherine Gorle, Clara Garciasanchez, Gianluca IaccarinoAbstract:Abstract Reynolds-averaged Navier–Stokes (RANS) simulations are often used in the Wind Engineering practice for the analysis of turbulent bluff body flows. An approach that allows identifying the uncertainty related to the use of reduced-order turbulence models in RANS simulations would significantly increase the confidence in the use of simulation results as a basis for design decisions. In the present study we apply a strategy that enables quantifying these uncertainties by introducing perturbations in the Reynolds stress tensor to simulations of the flow in downtown Oklahoma City. The method is combined with a framework to quantify uncertainties in the inflow Wind direction and intensity, and the final result of the UQ approach is compared to field measurement data for the velocity at 13 locations in the downtown area.
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cfd modelling of small particle dispersion the influence of the turbulence kinetic energy in the atmospheric boundary layer
Atmospheric Environment, 2009Co-Authors: Catherine Gorle, J Van Beeck, Patrick Rambaud, G Van TendelooAbstract:When considering the modelling of small particle dispersion in the lower part of the Atmospheric Boundary Layer (ABL) using Reynolds Averaged Navier Stokes simulations, the particle paths depend on the velocity profile and on the turbulence kinetic energy, from which the fluctuating velocity components are derived to predict turbulent dispersion. It is therefore important to correctly reproduce the ABL, both for the velocity profile and the turbulence kinetic energy profile. For RANS simulations with the standard k–e model, Richards and Hoxey (1993. Appropriate boundary conditions for computational Wind Engineering models using the k–e turbulence model. Journal of Wind Engineering and Industrial Aerodynamics 46–47, 145–153.) proposed a set of boundary conditions which result in horizontally homogeneous profiles. The drawback of this method is that it assumes a constant profile of turbulence kinetic energy, which is not always consistent with field or Wind tunnel measurements. Therefore, a method was developed which allows the modelling of a horizontally homogeneous turbulence kinetic energy profile that is varying with height. By comparing simulations performed with the proposed method to simulations performed with the boundary conditions described by Richards and Hoxey (1993. Appropriate boundary conditions for computational Wind Engineering models using the k–e turbulence model. Journal of Wind Engineering and Industrial Aerodynamics 46–47, 145–153.), the influence of the turbulence kinetic energy on the dispersion of small particles over flat terrain is quantified.
Seymour M J Spence - One of the best experts on this subject based on the ideXlab platform.
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a performance based Wind Engineering framework for envelope systems of engineered buildings subject to directional Wind and rain hazards
Journal of Structural Engineering-asce, 2020Co-Authors: Zhicheng Ouyang, Seymour M J SpenceAbstract:AbstractThe adoption of performance-based Wind Engineering (PBWE) is rapidly becoming recognized as a fundamental step to reducing the huge economic losses caused by severe Windstorms. This has led...
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framework for modeling interdependent effects in natural disasters application to Wind Engineering
Journal of Structural Engineering-asce, 2019Co-Authors: Szuyun Lin, Seymour M J Spence, Weichu Chuang, Sherif Eltawil, Vineet R Kamat, Carol C Menassa, Jason MccormickAbstract:AbstractModeling the various aspects of a disaster scenario and the interactions that occur between them is necessary to create a meaningful and high-fidelity simulation of the event. Using a publi...
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a performance based design framework for the integrated collapse and non collapse assessment of Wind excited buildings
Engineering Structures, 2017Co-Authors: Weichu Chuang, Seymour M J SpenceAbstract:Abstract Current prescriptive design provisions are moving towards performance-based design approaches in which system-level probabilistic measures are used to explicitly describe performance. While earthquake Engineering has embraced these changes over the last few decades, the same cannot be said for Wind Engineering where design provisions have remained predominantly prescriptive. The significant Wind related economic losses incurred each year around the world has spurred strong interest in developing general performance-based Wind Engineering frameworks. To this end, this paper presents a simulation-based framework for multistory Wind excited buildings that rigorously integrates system-level estimates of both collapse and non-collapse losses. In particular, it is proposed to use the theory of dynamic shakedown as an efficient means for describing the collapse probability of the main Wind force resisting system. The practicality and potential of the proposed framework is illustrated on a full scale case study.
G Van Tendeloo - One of the best experts on this subject based on the ideXlab platform.
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cfd modelling of small particle dispersion the influence of the turbulence kinetic energy in the atmospheric boundary layer
Atmospheric Environment, 2009Co-Authors: Catherine Gorle, J Van Beeck, Patrick Rambaud, G Van TendelooAbstract:When considering the modelling of small particle dispersion in the lower part of the Atmospheric Boundary Layer (ABL) using Reynolds Averaged Navier Stokes simulations, the particle paths depend on the velocity profile and on the turbulence kinetic energy, from which the fluctuating velocity components are derived to predict turbulent dispersion. It is therefore important to correctly reproduce the ABL, both for the velocity profile and the turbulence kinetic energy profile. For RANS simulations with the standard k–e model, Richards and Hoxey (1993. Appropriate boundary conditions for computational Wind Engineering models using the k–e turbulence model. Journal of Wind Engineering and Industrial Aerodynamics 46–47, 145–153.) proposed a set of boundary conditions which result in horizontally homogeneous profiles. The drawback of this method is that it assumes a constant profile of turbulence kinetic energy, which is not always consistent with field or Wind tunnel measurements. Therefore, a method was developed which allows the modelling of a horizontally homogeneous turbulence kinetic energy profile that is varying with height. By comparing simulations performed with the proposed method to simulations performed with the boundary conditions described by Richards and Hoxey (1993. Appropriate boundary conditions for computational Wind Engineering models using the k–e turbulence model. Journal of Wind Engineering and Industrial Aerodynamics 46–47, 145–153.), the influence of the turbulence kinetic energy on the dispersion of small particles over flat terrain is quantified.
Anthony M Vassallo - One of the best experts on this subject based on the ideXlab platform.
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Wind Engineering analysis of parabolic trough collectors to optimise Wind loads and heat loss
Energy Procedia, 2015Co-Authors: J Paetzold, Steve Cochard, David Fletcher, Anthony M VassalloAbstract:Abstract Concentrating Solar Power (CSP) plants tend to be located in open areas. This leads to the power plant usually being subjected to high Wind speeds without much shelter or protection. In parabolic trough plants the solar field, the collectors and receiver tubes, are affected by the Wind on both the structural, as well as the performance level. The collectors must resist the aerodynamic forces caused by the Wind, and the airflow around the receiver tube has a cooling effect on it. The effects of the Wind on Parabolic Trough Collectors (PTC) were investigated in a parametric study over a large range of pitch and yaw angles. Three different trough geometries were analysed varying the focal length of the parabola, i.e. the depth of the trough. The data were obtained using the Computational Fluid Dynamics (CFD) package ANSYS CFX 15.0 and validated against experimental data. An increase of the depth of the parabolic trough increases the maximum aerodynamic forces on the trough. However, a deeper trough has a sheltering effect on the receiver tube, thus reducing the thermal losses due to forced convection. This effect becomes more important the higher the temperature difference between the receiver and ambient air, and it can also reduce the requirements for highly insulated evacuated receiver tubes, which are a significant cost factor in PTC plants. The highest force coefficients on the PTC are observed at high positive pitch angles and a yaw angle of 0°. While the aerodynamic loads on the trough reduce significantly with an increase in the yaw angle of the approaching Wind, the heat flux around the receiver tube only shows a slight decrease in most cases. At some negative pitch angles an increasing yaw angle leads to higher thermal losses, as a vortex, forming at the leading edge of the trough, causes high air velocities around the receiver.
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Wind Engineering analysis of parabolic trough solar collectors: The effects of varying the trough depth
Journal of Wind Engineering and Industrial Aerodynamics, 2014Co-Authors: J Paetzold, Steve Cochard, Anthony M Vassallo, David F. FletcherAbstract:Abstract Wind affects parabolic trough solar collectors on both the structural and performance levels. With the need for higher temperatures, larger apertures of the troughs are required to increase the concentration ratio, however, this also increases the Wind loads on the structure. Additionally, airflow around the receiver tube adversely affects the performance of the plant by increasing convective heat losses. This paper presents the results of research into the effects of the Wind on parabolic trough solar collectors. The airflow is investigated in a parametric study aiming at a reduction of the Wind loads and thermal losses in the receiver tubes to provide a basis for higher concentration ratios and thus higher efficiencies of parabolic trough power plants. Validated against experimental data from Wind tunnel tests and previous studies on the Wind effects on parabolic troughs, a series of three-dimensional simulations was conducted using the commercial CFD program ANSYS ® CFX 14.5. The parameter that was varied is the depth of the trough, i.e. the focal length of the paraboloid. Simulations were performed over a large range of pitch angles for three different trough geometries as periodic simulations of an individual trough, representing a single collector row. Time-averaged data on aerodynamic loads and heat transfer are presented. While a deep trough leads to higher forces than a shallow trough, when facing the Wind, due to increased curvature, the Wind speed around the receiver is significantly lower with a lower focal length, which can minimise the heat loss in the receiver tube leading to overall higher efficiencies due to higher possible temperatures in the solar field.
Giovanni Solari - One of the best experts on this subject based on the ideXlab platform.
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Wind tunnel experimentation on stationary downbursts at Windeee dome
XV Conference of the Italian Association for Wind Engineering IN-VENTO 2018, 2018Co-Authors: Massimiliano Burlando, Horia Hangan, Djordje Romanic, Giovanni SolariAbstract:In the context of the European Project THUNDERR a scientific collaboration between the Wind Engineering and Structural Dynamics (Windyn) Research Group of the University of Genoa (Italy) and the Wind Engineering, Energy and Environment (WindEEE) Research Institute of Western University (Canada) has been established to study experimentally at the WindEEE Dome facility how the main geometrical and mechanical properties of downbursts are affected by different cloud base outflows of stationary thunderstorms. At present, the analysis of the downbursts simulated experimentally is ongoing and some preliminary elaborations have been obtained concerning the qualitative and quantitative interpretation of the corresponding signals. Classical signal decomposition was applied to experimentally produced downbursts in the WindEEE Dome in order to study transient features of the time series. This study presents the results for two radial positions from downdraft centre and for twenty repetitions per radial position. Several prospects for further research are also discussed.
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proper orthogonal decomposition in Wind Engineering part 1 a state of the art and some prospects
Wind and Structures, 2007Co-Authors: Giovanni Solari, Luigi Carassale, Federica TubinoAbstract:The Proper Orthogonal Decomposition (POD) is a statistical method particularly suitable and versatile for dealing with many problems concerning Wind Engineering and several other scientific and humanist fields. POD represents a random process as a linear combination of deterministic functions, the POD modes, modulated by uncorrelated random coefficients, the principal components. It owes its popularity to the property that only few terms of the series are usually needed to capture the most energetic coherent structures of the process, and a link often exists between each dominant mode and the main mechanisms of the phenomenon. For this reason, POD modes are normally used to identify low-dimensional subspaces appropriate for the construction of reduced models. This paper provides a state-of-the-art and some prospects on POD, with special regard to its framework and applications in Wind Engineering. A wide bibliography is also reported.
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proper orthogonal decomposition in Wind Engineering part 2 theoretical aspects and some applications
Wind and Structures, 2007Co-Authors: Luigi Carassale, Giovanni Solari, Federica TubinoAbstract:Few mathematical methods attracted theoretical and applied researches, both in the scientific and humanist fields, as the Proper Orthogonal Decomposition (POD) made throughout the last century. However, most of these fields often developed POD in autonomous ways and with different names, discovering more and more times what other scholars already knew in different sectors. This situation originated a broad band of methods and applications, whose collation requires working out a comprehensive viewpoint on the representation problem for random quantities. Based on these premises, this paper provides and discusses the theoretical foundations of POD in a homogeneous framework, emphasising the link between its general position and formulation and its prevalent use in Wind Engineering. Referring to this framework, some applications recently developed at the University of Genoa are shown and revised. General remarks and some prospects are finally drawn.
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double modal transformation and Wind Engineering applications
Journal of Engineering Mechanics-asce, 2001Co-Authors: Luigi Carassale, Giuseppe Piccardo, Giovanni SolariAbstract:Modal transformation techniques are usually adopted in structural dynamics with the aim of de- coupling the equations of motion. They are based on the search for an abstract space in which the solution of the problem results simplified. Analogous transformation techniques have recently been developed with the aim of defining a space where a multivariate stochastic process is expressed by a linear combination of one-variate uncorrelated processes. This paper proposes a method, called double modal transformation, by which the dynamic analysis of a linear structure is carried out through the simultaneous transformation of the equations of motion and the loading process. By adopting this technique, the structural response is obtained through a double series expansion in which structural and loading modal contributions are superimposed. Its effectiveness and application are discussed with reference to two classic Wind Engineering problems—the alongWind response and the vortex- induced crossWind response of slender structures—which provide a wide panorama of the most relevant prop- erties of this procedure. The dynamic analysis of structures is generally carried out by transforming the equations of motion from the initial La- grangian space into a new space characterized by particular properties. The choice of the transformation is usually driven by the necessity of reducing the computational size of the problem and by the opportunity of representing the system selecting a set of parameters with a suitable mechanical mean- ing. The classic modal analysis (Hurty and Rubinstein 1964) performs both these tasks by defining a principal space in which the motion of the structure can be represented through a limited number of principal coordinates. Under suitable con- ditions concerning the damping (Caughey 1960), moreover, such coordinates are orthogonal in a mechanical sense, i.e., are governed by decoupled equations. Load terms do not take part in the definition of the transformation law and assume, in the new space, a pure mathematical meaning. If the load is a mul- tivariate stochastic process, as happens for the Wind, its pro- jection on the transformed space is numerically very burden- some. The loading process may be transformed following analo- gous principles of the modal analysis by the proper orthogonal
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modal transformation tools in structural dynamics and Wind Engineering
Wind and Structures, 2000Co-Authors: Giovanni Solari, Luigi CarassaleAbstract:Structural dynamics usually applies modal transformation rules aimed at de-coupling and/orrnminimizing the equations of motion. Proper orthogonal decomposition provides mathematical andrnconceptual tools to define suitable transformed spaces where a multi-variate and/or multi-dimensionalrnrandom process is represented as a linear combination of one-variate and one-dimensional uncorrelatedrnprocesses. Double modal transformation is the joint application of modal analysis and proper orthogonalrndecomposition applied to the loading process. By adopting this method the structural response is expressed as arndouble series expansion in which structural and loading mode contributions are superimposed. Thernsimultaneous use of the structural modal truncation, the loading modal truncation and the cross-modalrnorthogonality property leads to efficient solutions that take into account only a few structural and loadingrnmodes. In addition the physical mechanisms of the dynamic response are clarified and interpreted.