Environmental Fluid Mechanics

Rubin, Hillel; Atkinson, Joseph F.; Sanderson, Brian G.

doi:10.1201/9780203908495

Cited by 47 publications

(21 citation statements)

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“…Eddies in the same size of particles make the most effective particle interactions (as shown in Fig. 3) [14]. An eddy that is smaller than the particle size will not take the movement and only affect the pollutant transport condition near the surface of the particles in the surrounding water.…”

Section: Eddy Diffusivitymentioning

confidence: 99%

“…8. For a spherical particle of radius R, the mathematical expression of these transport processes can be described as [14] …”

Section: Dynamic Micro-diffusion Modelmentioning

confidence: 99%

“…Equilibrium assumption may result in the wrong estimation of sediment release. As the source of the sediment and pollutant transport in the water environment system, the distribution of pollutants in the water is of great importance [14].…”

Section: Dynamic Micro-diffusion Modelmentioning

confidence: 99%

“…However, the residence time of particles suspended in the water column is much shorter than that of pollutants desorption. So it is difficult to establish the mathematical model of pollutant concentration variation in the overlying water [14]. The main difficulty lies in sediment desorption-adsorption behaviors and are influenced by many factors, such as contaminant characteristics, particle properties, sediment transport, and flow turbulence.…”

Section: Introductionmentioning

confidence: 99%

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Empirical model for estimating vertical concentration profiles of re-suspended, sediment-associated contaminants

Zhu

Cheng²,

et al. 2017

Acta Mech. Sin.

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Vertical distribution processes of sediment contaminants in water were studied by flume experiments. Experimental results show that settling velocity of sediment particles and turbulence characteristics are the major hydrodynamic factors impacting distribution of pollutants, especially near the bottom where particle diameter is similar in size to vortex structure. Sediment distribution was uniform along the distance, while contaminant distribution slightly lagged behind the sediment. The smaller the initial sediment concentration was, the more time it took to achieve a uniform concentration distribution for suspended sediment. A contaminants transportation equation was established depending on mass conservation equations. Two mathematical estimation models of pollutant distribution in the overlying water considering adsorption and desorption were devised based on vertical distribution of suspended sediment: equilibrium partition model and dynamic micro-diffusion model. The ratio of time scale between the sediment movement and sorption can be used as the index of the models. When this ratio was large, the equilibrium assumption was reasonable, but when it was small, it might require dynamic micro-diffusion model.

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Section: Eddy Diffusivitymentioning

confidence: 99%

“…8. For a spherical particle of radius R, the mathematical expression of these transport processes can be described as [14] …”

Section: Dynamic Micro-diffusion Modelmentioning

confidence: 99%

Section: Dynamic Micro-diffusion Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Empirical model for estimating vertical concentration profiles of re-suspended, sediment-associated contaminants

Zhu

Cheng²,

et al. 2017

Acta Mech. Sin.

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“…The transformation to higher resolution levels goes similarly to (24)(25)(26)(27)(28), except, that with each use of the refinement equation, the number of the elements φ m,i , R k (x)φ n, doubles, so for higher resolution levels an exponentially increasing number of lower resolution level integrals should be taken into account.…”

Section: Matrix Elements For Discontinuous Functionsmentioning

confidence: 99%

On Wavelet Based Modeling of the Nitrogen Oxides Emission and Concentration due to Road Traffic in Urban Environment

Nagy

2015

Acta Tech Jaur

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Differential equations can be solved wavelet-based by representing the continuous functions by their wavelet expansion coefficients and thus the corresponding differential equations are transformed to matrix equations. The wavelet basis functions are organized into resolution levels of different frequency terms at different locations, and the main advantage of the wavelet expansion representation is that the wavelet based differential equation solving methods can be adaptive, it is possible to refine the solution locally, if the precision is not sufficient at some regions. In case of the nitrogen oxides convection-advection equation, the urban environment should be taken as special material parameter in the differential equation's operator, and the matrix elements of the differential operator has to be calculated in a non-continuous environment, and the obstacles are placed so, that they are not at the boundaries of the support of the wavelets.

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Coping with model error in variational data assimilation using optimal mass transport

Ning

Carli

Ebtehaj

et al. 2014

Water Resources Research

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Classical variational data assimilation methods address the problem of optimally combining model predictions with observations in the presence of zero-mean Gaussian random errors. However, in many natural systems, uncertainty in model structure and/or model parameters often results in systematic errors or biases. Prior knowledge about such systematic model error for parametric removal is not always feasible in practice, limiting the efficient use of observations for improved prediction. The main contribution of this work is to advocate the relevance of transportation metrics for quantifying nonrandom model error in variational data assimilation for nonnegative natural states and fluxes. Transportation metrics (also known as Wasserstein metrics) originate in the theory of Optimal Mass Transport (OMT) and provide a nonparametric way to compare distributions which is natural in the sense that it penalizes mismatch in the values and relative position of ''masses'' in the two distributions. We demonstrate the promise of the proposed methodology using 1-D and 2-D advection-diffusion dynamics with systematic error in the velocity and diffusivity parameters. Moreover, we combine this methodology with additional regularization functionals, such as the ' 1 -norm of the state in a properly chosen domain, to incorporate both model error and potential prior information in the presence of sparsity or sharp fronts in the underlying state of interest.

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Environmental Fluid Mechanics

Cited by 47 publications

References 0 publications

Empirical model for estimating vertical concentration profiles of re-suspended, sediment-associated contaminants

Empirical model for estimating vertical concentration profiles of re-suspended, sediment-associated contaminants

On Wavelet Based Modeling of the Nitrogen Oxides Emission and Concentration due to Road Traffic in Urban Environment

Coping with model error in variational data assimilation using optimal mass transport

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