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Ricardo Camargo - One of the best experts on this subject based on the ideXlab platform.
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A Surface-Layer Study of the Transport and Dissipation of Turbulent Kinetic Energy and the Variances of Temperature, Humidity and CO $$_2$$
Boundary-Layer Meteorology, 2017Co-Authors: João A. Hackerott, Mostafa Bakhoday paskyabi, Joachim Reuder, Amauri P. Oliveira, Stephan T. Kral, Edson P. Marques filho, Michel Dos Santos Mesquita, Ricardo CamargoAbstract:We discuss scalar similarities and dissimilarities based on analysis of the Dissipation Terms in the variance budget equations, considering the turbulent kinetic energy and the variances of temperature, specific humidity and specific CO $$_2$$ 2 content. For this purpose, 124 high-frequency sampled segments are selected from the Boundary Layer Late Afternoon and Sunset Turbulence experiment. The consequences of Dissipation similarity in the variance transport are also discussed and quantified. The results show that, for the convective atmospheric surface layer, the non-dimensional Dissipation Terms can be expressed in the framework of Monin–Obukhov similarity theory and are independent of whether the variable is temperature or moisture. The scalar similarity in the Dissipation Term implies that the characteristic scales of the atmospheric surface layer can be estimated from the respective rate of variance Dissipation, the characteristic scale of temperature, and the Dissipation rate of temperature variance.
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a surface layer study of the transport and Dissipation of turbulent kinetic energy and the variances of temperature humidity and co formula see text
Boundary-Layer Meteorology, 2017Co-Authors: João A. Hackerott, Joachim Reuder, Amauri P. Oliveira, Stephan T. Kral, Michel Dos Santos Mesquita, Mostafa Bakhoday Paskyabi, Edson Marques P Filho, Ricardo CamargoAbstract:We discuss scalar similarities and dissimilarities based on analysis of the Dissipation Terms in the variance budget equations, considering the turbulent kinetic energy and the variances of temperature, specific humidity and specific CO[Formula: see text] content. For this purpose, 124 high-frequency sampled segments are selected from the Boundary Layer Late Afternoon and Sunset Turbulence experiment. The consequences of Dissipation similarity in the variance transport are also discussed and quantified. The results show that, for the convective atmospheric surface layer, the non-dimensional Dissipation Terms can be expressed in the framework of Monin–Obukhov similarity theory and are independent of whether the variable is temperature or moisture. The scalar similarity in the Dissipation Term implies that the characteristic scales of the atmospheric surface layer can be estimated from the respective rate of variance Dissipation, the characteristic scale of temperature, and the Dissipation rate of temperature variance.
Huazhong Tang - One of the best experts on this subject based on the ideXlab platform.
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entropy stable adaptive moving mesh schemes for 2d and 3d special relativistic hydrodynamics
Journal of Computational Physics, 2021Co-Authors: Junming Duan, Huazhong TangAbstract:Abstract This paper develops entropy stable (ES) adaptive moving mesh schemes for the 2D and 3D special relativistic hydrodynamic (RHD) equations. They are built on the ES finite volume approximation of the RHD equations in curvilinear coordinates, the discrete geometric conservation laws, and the mesh adaptation implemented by iteratively solving the Euler-Lagrange equations of the mesh adaption functional in the computational domain with suitably chosen monitor functions. First, a sufficient condition is proved for the two-point entropy conservative (EC) flux, by mimicking the derivation of the continuous entropy identity in curvilinear coordinates and using the discrete geometric conservation laws given by the conservative metrics method. Based on such sufficient condition, the EC fluxes for the RHD equations in curvilinear coordinates are derived and the second-order accurate semi-discrete EC schemes are developed to satisfy the entropy identity for the given convex entropy pair. Next, the semi-discrete ES schemes satisfying the entropy inequality are proposed by adding a suitable Dissipation Term to the EC scheme and utilizing linear reconstruction with the minmod limiter in the scaled entropy variables in order to suppress the numerical oscillations of the above EC scheme. Then, the semi-discrete ES schemes are integrated in time by using the second-order strong stability preserving explicit Runge-Kutta schemes. Finally, several numerical results show that our 2D and 3D ES adaptive moving mesh schemes effectively capture the localized structures, such as sharp transitions or discontinuities, and are more efficient than their counterparts on uniform mesh.
Hajime Mase - One of the best experts on this subject based on the ideXlab platform.
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multi directional random wave transformation model based on energy balance equation
Coastal Engineering Journal, 2001Co-Authors: Hajime MaseAbstract:The purpose of this paper is to develop a prediction model for multi-directional random wave transformation. The wave prediction model is based on an energy balance equation with an energy Dissipation Term and a newly formulated wave diffraction Term from a parabolic approximation wave theory; the wave model is stable when solved numerically. The model calculations are carried out for three cases: the first case is the wave tranformation through a gap between two breakwaters and the predictions are compared with the solutions of the Sommerfeld diffraction theory; the second case is the wave deformation due to an elliptic shoal and the predictions are compared with the experimental observations; the third case is the transformation of swells propagating into the Osaka Bay through narrow channels. These model calculations showed that the proposed wave model gives reasonable predictions.
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spectrum based prediction model for random wave transformation over arbitrary bottom topography
Coastal Engineering Journal, 2000Co-Authors: Hajime Mase, Toshikazu KitanoAbstract:This paper proposes a one-dimensional and a horizontally two-dimensional random wave transformation models based on a spectral wave equation with a probabilistic bore-type energy Dissipation Term, and examines the validity of the wave models by comparing the predictions with the observations. The present spectrum-based prediction models with a probabilistic Dissipation Term are rather heuristic but robust to use. Since the present random wave transformation models consist of spectral and probabilistic models, the wave model can be called as a hybrid random wave transformation model. The model solves the spatial evolution of complex Fourier amplitudes from which energy spectra are calculated. In addition, water surface elevations are obtained from the calculated complex amplitudes by using the inverse Fast Fourier Transform. Furthermore, representative wave heights and periods are obtained from the water surface elevations. We apply the one-dimensional wave model to predict transformations of double peak spectral waves, small and prototype scales' experimental waves and field waves over uniform slope and arbitrary bathymetry. In addition, the horizontally two-dimensional wave model is applied to predict transformations over an elliptic shoal, a conic shoal and field bathymetry, and also employed to investigate the mach-reflection. The comparison between the various observations by laboratory and field experiments and the predictions by the wave models shows good agreements.
T G Leighton - One of the best experts on this subject based on the ideXlab platform.
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the rayleigh plesset equation in Terms of volume with explicit shear losses
Ultrasonics, 2008Co-Authors: T G LeightonAbstract:The most common nonlinear equation of motion for the damped pulsation of a spherical gas bubble in an infinite body of liquid is the Rayleigh–Plesset equation, expressed in Terms of the dependency of the bubble radius on the conditions pertaining in the gas and liquid (the so-called ‘radius frame’). However over the past few decades several important analyses have been based on a heuristically derived small-amplitude expansion of the Rayleigh–Plesset equation which considers the bubble volume, instead of the radius, as the parameter of interest, and for which the Dissipation Term is not derived from first principles. So common is the use of this equation in some fields that the inherent differences between it and the ‘radius frame’ Rayleigh–Plesset equation are not emphasised, and it is important in comparing the results of the two equations to understand that they differ both in Terms of damping, and in the extent to which they neglect higher order Terms. This paper highlights these differences. Furthermore, it derives a ‘volume frame’ version of the Rayleigh–Plesset equation which contains exactly the same basic physics for Dissipation, and retains Terms to the same high order, as does the ‘radius frame’ Rayleigh–Plesset equation. Use of this equation will allow like-with-like comparisons between predictions in the two frames.
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derivation of the rayleigh plesset equation in Terms of volume
2007Co-Authors: T G LeightonAbstract:The most common nonlinear equations of motion for the pulsation of a spherical gas bubble in an infinite body of liquid arise in the various forms of the Rayleigh-Plesset equation, expressed in Terms of the dependency of the bubble radius on the conditions pertaining in the gas and liquid. However over the past few decades several important analyses have begun with a heuristically-derived form of the Rayleigh-Plesset equation which considers the bubble volume, instead of the radius, as the parameter of interest, and for which the Dissipation Term is not derived from first principles. The predictions of these two sets of equations can differ in important ways, largely through differences between the methods chosen to incorporate damping. As a result this report derives the Rayleigh-Plesset equation in Terms of the bubble volume from first principles in such a way that it has the same physics for Dissipation (viscous shear) as is used in the radius frame
Guangwu Yan - One of the best experts on this subject based on the ideXlab platform.
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a higher order moment method of the lattice boltzmann model for the conservation law equation
Applied Mathematical Modelling, 2010Co-Authors: Yinfeng Dong, Jianying Zhang, Guangwu YanAbstract:Abstract In this paper, we proposed a higher-order moment method in the lattice Boltzmann model for the conservation law equation. In contrast to the lattice Bhatnagar–Gross–Krook (BGK) model, the higher-order moment method has a wide flexibility to select equilibrium distribution function. This method is based on so-called a series of partial differential equations obtained by using multi-scale technique and Chapman–Enskog expansion. According to Hirt’s heuristic stability theory, the stability of the scheme can be controlled by modulating some special moments to design the third-order dispersion Term and the fourth-order Dissipation Term. As results, the conservation law equation is recovered with higher-order truncation error. The numerical examples show the higher-order moment method can be used to raise the accuracy of the truncation error of the lattice Boltzmann scheme for the conservation law equation.
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a higher order moment method of the lattice boltzmann model for the korteweg de vries equation
Mathematics and Computers in Simulation, 2009Co-Authors: Guangwu Yan, Jianying ZhangAbstract:In this paper, a lattice Boltzmann model for the Korteweg-de Vries (KdV) equation with higher-order accuracy of truncation error is presented by using the higher-order moment method. In contrast to the previous lattice Boltzmann model, our method has a wide flexibility to select equilibrium distribution function. The higher-order moment method bases on so-called a series of lattice Boltzmann equation obtained by using multi-scale technique and Chapman-Enskog expansion. We can also control the stability of the scheme by modulating some special moments to design the dispersion Term and the Dissipation Term. The numerical example shows the higher-order moment method can be used to raise the accuracy of truncation error of the lattice Boltzmann scheme.