The Experts below are selected from a list of 297 Experts worldwide ranked by ideXlab platform
Nicola De Divitiis - One of the best experts on this subject based on the ideXlab platform.
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Steady homogeneous turbulence in the presence of an Average Velocity gradient
International Journal of Engineering Science, 2012Co-Authors: Nicola De DivitiisAbstract:Abstract We study the homogeneous turbulence in the presence of a constant Average Velocity gradient in an infinite fluid domain, with a novel finite-scale Lyapunov analysis, presented in a previous work dealing with the homogeneous isotropic turbulence. Here, the energy spectrum is studied introducing the spherical Averaged pair correlation function, whereas the anisotropy caused by the Velocity gradient is analyzed using the equation of the two points Velocity distribution function which is determined through the Liouville theorem. As a result, we obtain the evolution equation of this Velocity correlation function which is shown to be valid also when the fluid motion is referred with respect to a rotating reference frame. This equation tends to the classical von Karman–Howarth equation when the Average Velocity gradient vanishes. We show that, the steady energy spectrum, instead of following the Kolmogorov law κ −5/3 , varies as κ −2 . Accordingly, the structure function of the longitudinal Velocity difference 〈 Δ u r n 〉 ≈ r ζ n exhibits the anomalous scaling ζ n ≈ n /2, and the integral scales of the correlation function are much smaller than those of the isotropic turbulence.
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Anisotropy and Anomalous Scaling in Steady Homogeneous Turbulence in the Presence of an Average Velocity Gradient
2010Co-Authors: Nicola De DivitiisAbstract:We study the homogeneous turbulence in the presence of a constant Average Velocity gradient in an infinite fluid domain, with a novel finite-scale Lyapunov analysis, presented in a previous work dealing with the homogeneous isotropic turbulence. Here, the energy spectrum is studied introducing the spherical Averaged pair correlation function, whereas the anisotropy caused by the Velocity gradient is analyzed using the equation of the two points Velocity distribution function which is determined through the Liouville theorem. As a result, we obtain the evolution equation of this Velocity correlation function which is shown to be valid also when the fluid motion is referred with respect to a rotating reference frame. This equation tends to the classical von Karman-Howarth equation when the Average Velocity gradient vanishes. We show that, the steady energy spectrum, instead of following the Kolmogorov law $\kappa^{-5/3}$, varies as $\kappa^{-2}$. Accordingly, the structure function of the longitudinal Velocity difference $ \approx r^{\zeta_n}$ exhibits the anomalous scaling $\zeta_n \approx n/2$, and the integral scales of the correlation function are much smaller than those of the isotropic turbulence.
Eng Choon Leong - One of the best experts on this subject based on the ideXlab platform.
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application of weighted Average Velocity wave method to determine vs 30
Soils and Foundations, 2015Co-Authors: A M W Aung, Eng Choon LeongAbstract:Abstract The weighted Average Velocity (WAVe) method was recently proposed as an alternative inversion algorithm for obtaining shear-wave Velocity (Vs) profiles from Rayleigh wave dispersion curves. In this paper, the WAVe method is discussed in relation to its accuracy in estimating the Average shear-wave Velocity to 30 m (Vs,30) and to other depths (Vs,z). Values for Vs,30 are used in building codes to determine ground-type classes for seismic design. Five case studies, representing typical shear-wave Velocity (Vs) profiles, are presented. The Vs profiles obtained using the WAVe method and those obtained using more rigorous inversion methods were quantitatively compared based on Vs,30 as well as Vs, z. The comparison showed that the WAVe method yielded similar Vs profiles and Vs,30 leading to same ground type for seismic design.
A M W Aung - One of the best experts on this subject based on the ideXlab platform.
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application of weighted Average Velocity wave method to determine vs 30
Soils and Foundations, 2015Co-Authors: A M W Aung, Eng Choon LeongAbstract:Abstract The weighted Average Velocity (WAVe) method was recently proposed as an alternative inversion algorithm for obtaining shear-wave Velocity (Vs) profiles from Rayleigh wave dispersion curves. In this paper, the WAVe method is discussed in relation to its accuracy in estimating the Average shear-wave Velocity to 30 m (Vs,30) and to other depths (Vs,z). Values for Vs,30 are used in building codes to determine ground-type classes for seismic design. Five case studies, representing typical shear-wave Velocity (Vs) profiles, are presented. The Vs profiles obtained using the WAVe method and those obtained using more rigorous inversion methods were quantitatively compared based on Vs,30 as well as Vs, z. The comparison showed that the WAVe method yielded similar Vs profiles and Vs,30 leading to same ground type for seismic design.
R. M. Sperandeo-mineo - One of the best experts on this subject based on the ideXlab platform.
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Construction and Validation of a Computer-Based Diagnostic Module on Average Velocity.
Journal of Research in Science Teaching, 1994Co-Authors: G. Andaloro, L. Bellomonte, L. Lupo, R. M. Sperandeo-mineoAbstract:This article describes the process of building a computer-based diagnostic module concerning the understanding of the Average Velocity concept. The first step consists of the production of a student model that takes into account student errors and reasoning paths. The computer module formulates its diagnosis by leading users along different patterns foreseen according to the hypothesized student model. Results are reported concerning a correlation analysis between automatic and human diagnoses.
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A computer-based diagnostic tutor for Average Velocity
Computers & Education, 1991Co-Authors: G. Andaloro, L. Bellononte, R. M. Sperandeo-mineoAbstract:Abstract The concept of Average Velocity is often misunderstood, even by students at university level. To analyse student reasoning about Average Velocity, students who were being instructed in kinematics in an introductory physics course were shown a series of computer animations of two cars moving independently. Their answers to subsequent questions tended to use partial knowledge elements present in the problem. On this basis, a list of eight procedures used by students was drawn up and used as the basis of a computer-based diagnostic tutor, Velo. The performance of Velo is being compared with human tutors.
Junlong Xie - One of the best experts on this subject based on the ideXlab platform.
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An alternative approach to quantifying fluid flow uniformity based on area-weighted Average Velocity and mass-weighted Average Velocity
Energy and Buildings, 2012Co-Authors: Hong-ge Tao, Huanxin Chen, Junlong XieAbstract:Abstract Fluid flow uniformity is an important index in many research fields including artificial environment in the room. In order to facilitate quantifying the multi-section flow uniformity directly by simulation results and to simplify the computation process, a correlation based on area-weighted Average velocities and mass-weighted Average velocities is proposed in this paper. To test the proposed approach to quantifying flow uniformity, the correlation is applied in two studies – one based on assumed Velocity distribution, another based on the simulated Velocity distribution – in comparison with two existing formulae from prior studies. The results show that the evaluation results of the proposed correlation are in complete agreement with that of the two formulae from prior studies in the overall trend. The correlation may be used in a wide range of contexts without strict requirement for uniformity to quantify the fluid uniformity in a relatively simple manner.
