Numerical modelling of aeolian erosion over a surface with non‐uniformly distributed roughness elements

Furieri, B.; Harion, J.‐L.; Milliez, Maya; Russeil, S.; Santos, Jane Méri

doi:10.1002/esp.3435

Cited by 11 publications

(6 citation statements)

References 43 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In addition, greater amounts of non-erodible particles in the mixture led to a greater decay rate. These findings are consistent with previous studies in the literature [11,16]. A mathematical model for emitted mass estimates that includes the influence of the presence of non-erodible particles and saltation was proposed.…”

Section: Accepted Manuscriptsupporting

confidence: 92%

“…The computationalset up (modelling choices including meshing, turbulence closure and domain configurations) was based on previously validated numerical calculations (cf. [50] and [16]). Fig.…”

Section: Accepted Manuscriptmentioning

confidence: 98%

“…where and are respectively the frontal and the basal areas of a cylindrical roughness element, and , and N are coefficients determined by the numerical simulations. [16] found that Equation 7 is also valid for surfaces containing particles with different aspect ratios (non-uniform distribution of roughness elements). However, this formulation was tested for cover rates lower than 12%.…”

Section: Accepted Manuscriptmentioning

confidence: 99%

See 2 more Smart Citations

A simple model to estimate emission of wind-blown particles from a granular bed in comparison to wind tunnel experiments

Ferreira

Furieri

Moctar³

et al. 2019

Geomorphology

Self Cite

View full text Add to dashboard Cite

Dust emissions due to aeolian erosion of exposed granular materials are strongly influenced by grain size distribution. Non-erodible particles that are too heavy to be lifted into the air play a protective role in the aeolian erosion process attenuatingemission, which is known as the pavement phenomenon. To date, there is no approach that reliably predicts the reduction in emissions caused by their presence on an aggregate surface. In this work, an analytical model was developed to quantify emissions from particle beds with a wide size distribution. As non-erodible particles accumulate, changes in surface characteristics create increasing shelter for the erodible portion of the bed until the shear on the erodible surface reaches a minimum and emissions cease. The proposed emission model describes the relationship between this minimum value of wind shear and the eroded depth of the bed after the pavement, which in turn gives the emitted mass. In addition, wind tunnel experiments were carried out in order to broaden knowledge of the pavement phenomenon and validate the modelling. A bimodal particle size distribution of sand with erodible and non-erodible particles was used for the tested velocities. Three experimental measurements were carried out: (i) continuous weighing of the emitted mass, (ii) eroded depth of the bed at regular time intervals and (iii) final cover rates of the non-erodible particles using digital analysis of sand bed pictures after experiments. Good agreement between the modelling and experimental results was found. The emission model proposed herein is a simple algebraic expression that demands low computational effort. This approach may serve as a base for an emission model for application in granular materials stockpiles.

show abstract

Section: Accepted Manuscriptsupporting

confidence: 92%

Section: Accepted Manuscriptmentioning

confidence: 98%

Section: Accepted Manuscriptmentioning

confidence: 99%

See 1 more Smart Citation

A simple model to estimate emission of wind-blown particles from a granular bed in comparison to wind tunnel experiments

Ferreira

Furieri

Moctar³

et al. 2019

Geomorphology

Self Cite

View full text Add to dashboard Cite

show abstract

“…The characteristics of the fluid (e.g., viscosity, density) and of the flow field (e.g., speed, direction, depth) in combination with the characteristics of the sediment surface (e.g., grain size, mineral density, sorting, roundness, roughness, cohesion) determine the rate of sediment transport and thereby the scale and geometry of the bedform that is likely to exist for a specific set of state parameters. Supporting evidence comes from studies in wind tunnels (e.g., Walker andNickling, 2002, 2003;Dong et al, 2007) as well as a host of increasingly sophisticated numerical model simulations (e.g., Parsons et al, 2004;Araújo et al, 2013;Durán and Moore, 2013;Furieri et al, 2014) that demonstrate how equilibrium bedforms of varying geometry evolve, migrate, and interact with near-surface flow dynamics. Our conceptual understanding of dune dynamics is heavily pre-conditioned by such a steady state perspective (see comprehensive reviews by Bauer et al, 2013;Walker and Hesp, 2013;, which parallels ideas pertaining to fluvial bedforms (e.g., Venditti, 2013).…”

Section: Introductionmentioning

confidence: 98%

Sediment transport (dis)continuity across a beach–dune profile during an offshore wind event

et al. 2015

View full text Add to dashboard Cite

Flow dynamics and sediment transport responses over a large, vegetated foredune at Prince Edward Island, Canada, during an offshore wind event are examined. Data were collected along an instrumented transect that extended from the dune crest, down the lee-side (seaward) slope of the dune, across a wave-cut scarp, and on to the back-beach. When the wind direction at the dune crest was approximately crest-normal (less than about 15 o deviation), mean near-surface flow directions along the dune slope and on the back beach were generally onshore, indicating reversed (onshore) flow relative to the regional (offshore) wind direction. Although flow patterns were consistent with a lee-side recirculation eddy, large excursions in flow direction were also prevalent, suggesting that the eddy was unstable and alternated with highly turbulent wake flow. As wind direction at the crest veered to greater than 20 o from crest-normal, lee-side winds shifted toward strongly alongshore flow with minimal directionally variability. On the dune slope, the wind vectors were slightly offshore whereas on the back-beach they were slightly onshore.Wind speeds and sediment transport were greatest at the foredune crest and declined rapidly downslope due to flow expansion and deceleration in the wake zone as well as to the influence of a sparse vegetation layer. Mean particle counts (averaged over a 15-minute interval) derived from laser sensors positioned at the crest were large (7.76 per second) in comparison to those measured in the immediate lee of the crest (0.52 per second) and farther down the dune slope (< 0.13 per second).In contrast, the values were as large as 25.62 per second on the middle of the back-beach, declining rapidly to a value of only 0.24 per second at the dune toe. Transport intensity was highly variable with the largest Activity Parameter (AP = 0.5) values at the dune crest and on the back-beach, and with the smallest values (AP < 0.1) on the lee-side dune slope down to the top of the scarp. Calculations of sediment (particle) flux divergence between instrument stations show that deposition was significant A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT2 immediately downwind of the dune crest but negligible across most of the lower dune slope.Deposition was also prevalent on the dune ramp below the scarp.These results demonstrate that sediment transport across the beach-dune system was spatially discontinuous during this offshore wind event. Rebuilding of the dune ramp at the toe of the scarp occurred quite independently of, and with a different sediment source than, the broadening of the dune crest, which was fed with sediment from the landward side of the foredune. Such process 'decoupling'is an example of the complexity by which foredunes evolve or are maintained, and as with previous research reinforces the importance of offshore and alongshore wind events to beach-dune morphodynamics.

show abstract

“…In the four types of interference regions (i.e., wake interference region i, wake interference region ii, proximity interference region, and weak-interference region), the fluctuating across-wind force on the downstream building is significantly magnified, slightly magnified, largely reduced, and nearly unchanged, respectively (Zu & Lam, 2018). Furthermore, in water and aeolian systems, the spanwise flow plays a vital role in sand deposition (Burkow & Griebel, 2016;Furieri et al, 2014;Meire et al, 2014;Sutton & McKenna-Neuman, 2008a;Sutton & McKenna-Neuman, 2008b). Meire et al (2014) found that there was a secondary sedimentary region at the leeside of two neighboring vegetation patches, which was caused by the merging of adjacent horseshoe vortices.…”

Section: 1029/2019jf005199mentioning

confidence: 99%

Effects of Wind Velocity and Nebkha Geometry on Shadow Dune Formation

et al. 2019

View full text Add to dashboard Cite

Flow dynamics and sand deposition processes over nebkhas were investigated using computational fluid dynamics simulations, wind tunnel experiments, and field measurements. The computational fluid dynamics simulations showed that nebkha width affects both the elongation and broadening of the wind shadows. The length of the wind shadows decreased as the wind shear velocity increased, following a power function, irrespective of the width and height of the nebkha. There are some uncertainties about the effect of the aspect ratio of the nebkha on the formation of wind shadows as a result of the omission of the transport of sand in the simulations. It is suggested that the length of wind shadows is dependent on the absolute values of nebkha width and height rather than the nebkha aspect ratio. Although the numerical results were consistent with the results of the wind tunnel experiments, the wind tunnel experiments showed that the height of the nebkha had a negative effect on the elongation of the shadow dunes. The sedimentary structures revealed by ground‐penetrating radar surveys of the dunes in the Taitema Dry Lake, in the eastern Taklimakan Desert, China, showed that the formation of shadow dunes can be divided into three phases. Shadow dunes are initially controlled by horizontal separation flow and then elongate following the same growth mechanisms as linear dunes, eventually breaking up into isolated barchans or short, temporary linear dunes. However, the formation of shadow dunes does not necessarily call for the three phases depending on the local wind regime and sediment supply.

show abstract

Numerical modelling of aeolian erosion over a surface with non‐uniformly distributed roughness elements

Cited by 11 publications

References 43 publications

A simple model to estimate emission of wind-blown particles from a granular bed in comparison to wind tunnel experiments

A simple model to estimate emission of wind-blown particles from a granular bed in comparison to wind tunnel experiments

Sediment transport (dis)continuity across a beach–dune profile during an offshore wind event

Effects of Wind Velocity and Nebkha Geometry on Shadow Dune Formation

Contact Info

Product

Resources

About