Meiring Beyers

University of Ulster · School of Environmental Sciences

This study presents and validates a workflow that quantitatively links the rate of barchan dunes migration, which can be measured from remote sensing, to the wind velocity, either measured at a meteorological station or extracted from reanalysis data. The workflow requires the selection of a sand transport law and a procedure to estimate the effect...

Meso-scale airflow conditions can be observed at spatial scales of 2 – 2,000 km and temporal scales of days to months. In complex aeolian environments, where topographic steering alters regional airflow patterns, larger scale phenomena can modify micro-scale dune dynamics. Whole-island topographic steering has been observed around Gran Canaria, a h...

Airflow dynamics across dune surfaces are the primary agent of sediment transport and resulting dune migration movements. Using 3D computational fluid dynamic modelling, this study examined the behaviour of near surface airflow travelling over transverse (reversing) dunes on a beach system. Wind direction was modelled in two opposing directions (bo...

Dune length scale airflow modelling provides new insights on aeolian bedform response and complex near surface 3D wind patterns not previously resolved by mesoscale models. At a 1-m surface resolution, Curiosity wind data is used to investigate the aeolian environment of the Namib dune on Mars, providing improved seasonal constraints on grainfall,...

This study achieves the highest resolution of airflow modelling thus far in the study of martian aeolian dynamics by employing a High Resolution Imaging Science Experiment (HiRISE) Digital Terrain Model (DTM) of the Namib dune in Gale Crater at a 1-meter resolution. At this resolution, sub-dune scale bedforms, not previously resolved by mesoscale m...

Models relating wind forcing to resulting sand transport flux have been at the core of the discipline from its conception and remain an important central focus. The desired capability to accurately predict the amounts of sand that are moved in response to any given wind regime is one of the key practical applications of our scientific efforts. A pl...

Large-scale atmospheric turbulence can have a large impact on the regional wind regime effecting dune environments. Depending on the incident angle of mesoscale airflow, local topographic steering can also alter wind conditions and subsequent aeolian dynamics. This research analyses the influence of large-scale airflow perturbations occurring at th...

Un-vegetated dune fields provide excellent opportunities to examine airflow dynamics over various types and scales of dune landforms. The three dimensional surface over which lower boundary layers travel, help adjust surface airflow and consequently the aeolian response of the dunes themselves. The use of computational fluid dynamic (CFD) modelling...

An understanding of the role of open space and vegetation to mitigate heat-related health risks is invaluable to urban designers and policy makers. However, these professionals may be prevented from introducing extensive urban green space in urban (re)design projects as it competes against conventional and tangible urban real estate development ben...

Video clip (1 minute) showing offshore (oblique) directed winds, flow steering on the beach (alongshore) and return flow (onshore) through back eddy/detached from the dune crest detaching flow up and over into foredunes

Characterization of three-dimensional (3D) airflow remains elusive within a variety of environments and is particularly challenging over complex dune topography. Previous work examining airflow over and in the lee of dunes has been restricted to two-dimensional studies and has concentrated on dune shapes containing angle of repose lee sides only. H...

[1] Characterization of three-dimensional (3D) airflow remains elusive within a variety of environments and is particularly challenging over complex dune topography. Previous work examining airflow over and in the lee of dunes has been restricted to two-dimensional studies and has concentrated on dune shapes containing angle of repose lee sides onl...

Understanding the morphodynamics of beach-dune systems requires knowledge of the spatio-temporal variability of the sediment transport system. It is common in aeolian studies to employ a single transect instrument set up, oriented parallel to the wind direction. This experimental design assumes that there is no significant variation in sediment tra...

The transfer of windblown sand between foredune systems and beaches represents a key component of sediment budget analysis along many soft sedimentary coastlines. Traditionally, onshore wind components in local wind regimes are examined whereas offshore wind events have been excluded from analysis. Recent work has shown that if the topography of t...

Using computational fluid dynamics (OpenFoam CFD code) with a RNG k-ε solver over a 3-D surface mesh, we present preliminary findings within Mars’ Proctor Crater (fig.1) to examine a dune area of 4.4km x 3.0km, and a computational cell resolution of 5m x 5m. We ran three wind directions; Primary (WSW), Secondary (ESE) and Tertiary (ENE) winds. Each...

The past decade has seen a growing body of research on the relation between turbulence in the wind and the resultant transport of sediment over active sand surfaces. Widespread use of sonic anemometry and high-frequency sand transport sensors and traps have facilitated recent field studies over dunes and beach surfaces, to move beyond monitoring of...

The behaviour of offshore-directed winds over coastal dune and beach morphology was examined using a combination of modelling (3-D computational fluid dynamics (CFD)) and field measurement. Both model simulations and field measurements showed reversal of offshore flows at the back beach and creation of an onshore sediment transport potential. The i...

Exchange of windblown sand between beaches and coastal foredune systems is a key component of sediment budget analysis along many coastlines. The techniques employed to measure and understand processes operating within this key transitional zone have advanced rapidly in recent years, providing important data at a range of temporal and spatial scale...

Aeolian sediment input into coastal dunes represents a key component of sediment budget analysis of beach-dune systems. Calculations of sediment input to the foredunes are traditionally based on onshore winds, often excluding the role played by offshore wind events. However, recent work has shown that offshore flows play an essential role in post-s...

Calculations of aeolian sediment input to coastal foredunes are essential for sediment budget calculations and prediction of foredune evolution, as well as many practical applications such dune rehabilitation and coastal restoration. However, predictions of aeolian sediment transport at a scale of weeks to months are tenuous which poses major diffi...

This study examines aeolian sediment transport patterns across a beach at Magilligan Strand, Northern Ireland, under offshore wind conditions. Traditionally the offshore component of local wind regimes has been ignored when quantifying beach-dune sediment budgets, with the sheltering effect of the foredune assumed to prohibit grain entrainment on t...

The existence of onshore sediment transport under offshore winds has been identified as a primary mechanism for post-storm dune recovery and maintenance. However, airflow separation, lee-side eddies and secondary flows may play an essential role on the evolution of sand dunes in coastal areas where the dominant wind direction is offshore (lee side...

Delgado-Fernandez, I., Jackson, D.W.T., Cooper, JAG., Baas, A.C.W., Lynch' K. and Beyers' J.H.M., 2011. Reattachment zone characterisation under offshore winds blowing over complex foredune topography. Journal of Coastal Research, SI 64 (Proceedings of the 11th International Coastal Symposium), 273-277. Szczecin, Poland, ISSN 0749-0208 Studies of t...

Airflow separation, lee-side eddies and secondary flows play an essential role on the formation and maintenance of sand dunes. Downstream from dune crests the flow surface layer detaches from the ground and generates an area characterised by turbulent eddies in the dune lee slope (the wake). At some distance downstream from the dune crest, flow sep...

Recent studies have suggested the significant role of boundary layer turbulence and coherent flow structures on sand transport by wind over beaches and desert dunes. Widespread use of sonic anemometry and high-frequency sand transport sensors and traps have facilitated a move beyond the basic monitoring of shear velocities and bulk sediment transpo...

This study examines sand transport and wind speed across a beach at Magilligan Strand, Northern Ireland, under offshore wind conditions. Traditionally the offshore component of local wind regimes has been ignored when quantifying beach-dune sediment budgets, with the sheltering effect of the foredune assumed to prohibit grain entrainment on the adj...

Recent studies have suggested the significant role of boundary layer turbulence and coherent flow structures on sand transport by wind over beaches and desert dunes. Widespread use of sonic anemometry and high-frequency sand transport sensors and traps have facilitated a move beyond the basic monitoring of shear velocities and bulk sediment transpo...

The input of aeolian sediment into foredune systems from beaches represents a key component of sediment budget analysis along many soft sedimentary coastlines. Where there are significant offshore wind components in local wind regimes this is normally excluded from analysis. However, recent work has shown that if the topography of the foredune is f...

The past decade has seen a growing body of research on the relation between turbulence in the wind and the resultant transport of sediment over active sand surfaces. Widespread use of sonic anemometry and high-frequency sand transport sensors and traps have facilitated recent field studies over dunes and beach surfaces, to move beyond monitoring of...

Understanding airflow behaviour over three-dimensional foredune terrain allows detailed examination of the aeolian transport environment between beaches and dunes. A spatial array of twenty four ultrasonic anemometers was deployed in 2010 over a beach and foredune system at Magilligan, Northern Ireland to capture airflow data under a range of incid...

A fundamental criterion for the development of coastal sand dunes is usually highlighted as a significant onshore wind component of the local wind field. The presence of large sand dune systems on coasts where the predominant wind blows offshore is therefore difficult to explain and usually they are attributed to the past occurrence of onshore wind...

Foredune evolution has been conceptualized in a number of beach-dune interaction models. A fundamental aspect of this interaction is the input of sand from the beach to the dune by wind processes, which is essential in calculations of coastal dune budgets. The procedure to predict sediment input by wind to the adjacent coastal dune often excludes t...

The new campus for the King Abdullah University of Science and Technology (KAUST) will be located on the Red Sea coast near the fishing village of Thuwal, approximately 50 miles North of Jeddah in the Kingdom of Saudi Arabia. The main campus consists of two laboratory complexes, an administration building, engineering and applied mathematics buildi...

The prediction of wind driven snowdrift development around complex surface obstacles and elevated structures presently relies heavily on experience and experimental and numerical flow field analyses using, for example, boundary layer wind tunnels, cryospheric wind tunnels, water flumes and computational fluid dynamics (CFD). In this paper, a snowdr...

This paper presents the results of the numerical simulation of drifting snow surrounding a simple cubicle structure. These results are compared and verified against data from snow drifting experimental tests carried out at SANAE IV research station, Antarctica, during the summer research period of January 2002. In addition to the snow drifting fiel...

A numerical simulation is carried out to study the transient three-dimensional snow drifting phenomena surrounding an elevated structure. The method employs the commercial CFD software FLOW3D with additional user FORTRAN subroutines to facilitate the temporal modification of the computational domain to account for snow accumulation and erosion. The...

This paper describes the experimental modelling procedure and results to evaluate the snowdrift characteristics surrounding the research station of the South African National Antarctic Expedition, SANAE IV. For this purpose a 1:25 scale model of the research station was constructed and mounted on a large flat snow covered area in the vicinity of th...

This article describes a finite volume analysis for the three-dimensional numerical prediction of the thermofluid behavior of accelerating turbulent radial flows. The method employs nonorthogonal control volumes with a flux split method to assist the discretization of the general transport equations. A flux blended deferred correction interpolation...

A computational fluid dynamic (CFD) study analyzing wind effects on natural draft dry cooling towers was conducted. In the CFD study, a full scale dry cooling tower with en-vironment domain was modeled. The atmospheric boundary layer and thermally driven cooling tower flows were simulated. Reynolds-averaged Navier–Stokes (RANS) turbulence model was...

The elevated and aerodynamically streamlined South African Antarctic research base SANAE IV, in Queen Maud Land, off the Fimbul ice-shelf in Antarctica, exhibits unique wind driven snow drift formations. The longitudinal snowdrifts that form behind the intercon-necting links that join the elevated research buildings are approximately 4 m high, 15 m...

Understanding an urban microclimate including its wind distribution, thermal comfort characteristics and pollutant dispersion qualities remains an important component towards improved design for sustainable urbanism. These microclimatic characteristics are often assessed using physical or computational wind modeling, with coupling to local meteorol...

A process by which the energy potential within a site or master plan is determined. The process uses a combination of computed velocity fields, meteorological data and specific turbine information to generate wind energy potential data. A case study of a master plan is pre-sented along with the results obtained.