A Hybrid Spectral/Finite-Volume Algorithm for Large-Eddy Simulation of Scalars in the Atmospheric Boundary Layer

Chamecki, Marcelo; Meneveau, Charles; Parlange, Marc B.

doi:10.1007/s10546-008-9302-1

Cited by 43 publications

(38 citation statements)

References 25 publications

(31 reference statements)

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“…We note that we only work with mean flow fields and do not explicitly consider the highly turbulent flow nor the mostly intermittent snow transport. A logical further step would therefore be to make use of the advanced performance of Large-Eddy Simulations (Chamecki et al, 2008) to investigate the limits of our equilibrium descriptions. We further note that we have not simulated a full time development of the snow cover and in particular for the purpose of slope stability estimations based on weak layer modeling (Schirmer et al, 2010a).…”

Section: Discussionmentioning

confidence: 99%

Understanding snow-transport processes shaping the mountain snow-cover

Mott¹,

Schirmer²,

Bavay³

et al. 2010

The Cryosphere

157

188

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Abstract. Mountain snow-cover is normally heterogeneously distributed due to wind and precipitation interacting with the snow cover on various scales. The aim of this study was to investigate snow deposition and wind-induced snow-transport processes on different scales and to analyze some major drift events caused by north-west storms during two consecutive accumulation periods. In particular, we distinguish between the individual processes that cause specific drifts using a physically based model approach. Very high resolution wind fields (5 m) were computed with the atmospheric model Advanced Regional Prediction System (ARPS) and used as input for a model of snow-surface processes (Alpine3D) to calculate saltation, suspension and preferential deposition of precipitation. Several flow features during north-west storms were identified with input from a high-density network of permanent and mobile weather stations and indirect estimations of wind directions from snowsurface structures, such as snow dunes and sastrugis. We also used Terrestrial and Airborne Laser Scanning measurements to investigate snow-deposition patterns and to validate the model. The model results suggest that the in-slope deposition patterns, particularly two huge cross-slope cornicelike drifts, developed only when the prevailing wind direction was northwesterly and were formed mainly due to snow redistribution processes (saltation-driven). In contrast, more homogeneous deposition patterns on a ridge scale were formed during the same periods mainly due to preferential deposition of precipitation. The numerical analysis showed that snow-transport processes were sensitive to the changing topography due to the smoothing effect of the snow cover.

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Section: Discussionmentioning

confidence: 99%

Understanding snow-transport processes shaping the mountain snow-cover

Mott¹,

Schirmer²,

Bavay³

et al. 2010

The Cryosphere

157

188

View full text Add to dashboard Cite

show abstract

“…A filtered advection-diffusion equation including an additional term to represent gravitational settling (with constant settling velocity in the vertical direction) is used, and discretized using a finite-volume approach, with advection represented by the flux-limiting scheme SMART (Gaskell and Lau 1988) (see also Chamecki et al (2008) for more details). The constant settling velocity w s is defined by the terminal settling velocity in a still fluid, and is calculated via Stokes' law for a spherical particle…”

Section: Large-eddy Simulation Of Dust Concentration In the Atmosphermentioning

confidence: 99%

Flux-Profile Relationship for Dust Concentration in the Stratified Atmospheric Surface Layer

Freire

Chamecki

Gillies

2016

Boundary-Layer Meteorol

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Flux-profile relationships are usually obtained under the assumption that the mean field of interest is in equilibrium with the associated surface fluxes. In this study, the existence of an equilibrium state for dust concentration in the atmospheric surface layer above sources and sinks is evaluated using large-eddy simulation. Results show that for steady-state turbulence and negligible horizontal advection, an equilibrium mean vertical profile of dust concentration is reached after one boundary-layer eddy turnover time. This is true for cases over a source or sink, under different atmospheric stabilities, and for particles with negligible or significant settling velocity. A new model relating the net surface flux to the vertical concentration profile that accounts for both atmospheric stability and particle settling velocity is proposed. The model compares well with the simulation results for all particle sizes and atmospheric stability conditions evaluated, and it can be used to estimate the concentration profile based on the surface flux, and also to estimate the surface flux by fitting the vertical concentration profile. The resulting equation can be considered as an extension of MoninObukhov similarity theory to the concentration of settling particles, such as mineral dust, sea-salt, pollen and other suspended aerosols.

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“…The conservation of particle concentration is discretized using a finite-volume scheme with a third-order bounded scheme for the advection term (Chamecki, Meneveau & Parlange 2008). Following Chamecki & Meneveau (2011), the advective velocity for the particle concentration field is approximated as the superposition of the instantaneous fluid velocity and a constant particle settling velocity (which represents the 'mean drift' due to gravitational settling).…”

Section: Model Descriptionmentioning

confidence: 99%

Large-eddy simulation of turbulence and particle dispersion inside the canopy roughness sublayer

2014

Self Cite

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Modelling the dispersion of small particles such as fungal spores, pollens and small seeds inside and above plant canopies is important for many applications. Transport of these particles is driven by strongly inhomogeneous and non-Gaussian turbulent flows inside the canopy roughness sublayer, the region that extends from the ground to approximately three canopy heights. A large-eddy simulation (LES) approach is refined to study particle dispersion within and above the canopy region. Effects of plant reconfiguration are parameterized through a velocity-dependent drag coefficient, which is shown to be critical for accurate reproduction of velocity statistics and mean spore concentrations. The model yields predictions of turbulence statistics that are in good agreement with measurements. This is particularly true of the stress fractions carried by strong events, as revealed by standard quadrant analysis of the resolved velocity fluctuations, which is a known weakness of earlier LES studies of canopy flow using a constant drag coefficient. Experimental data on spore dispersal inside and above a maize canopy are reproduced successfully as well. Characteristics of the particle plume are analysed using LES results, and a pre-existing theoretical framework is adapted to model particle dispersal above the canopy. The results suggest that the plume above the canopy can be approximated using a simple analytical solution if the fraction of spores that escape the canopy region is known. Source height and gravitational settling have strong effects on the plume inside the canopy region and consequently determine the escape fraction. These effects are parameterized in the theoretical model by using the escape fraction to rescale the source strength.

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A Hybrid Spectral/Finite-Volume Algorithm for Large-Eddy Simulation of Scalars in the Atmospheric Boundary Layer

Cited by 43 publications

References 25 publications

Understanding snow-transport processes shaping the mountain snow-cover

Understanding snow-transport processes shaping the mountain snow-cover

Flux-Profile Relationship for Dust Concentration in the Stratified Atmospheric Surface Layer

Large-eddy simulation of turbulence and particle dispersion inside the canopy roughness sublayer

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