Author
A. J. Alexander
Bio: A. J. Alexander is an academic researcher from Loughborough University. The author has contributed to research in topics: Particle & Two-phase flow. The author has an hindex of 1, co-authored 1 publications receiving 2024 citations.
Topics: Particle, Two-phase flow, Reynolds number, Cylinder, Drag
Papers
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TL;DR: In this article, the authors describe a theoretical investigation into the response of a spherical particle to a one-dimensional fluid flow, and the motion of the spherical particle in a uniform 2D fluid flow about a circular cylinder.
Abstract: This paper describes a theoretical investigation into (i) the response of a spherical particle to a one-dimensional fluid flow, (ii) the motion of a spherical particle in a uniform two-dimensional fluid flow about a circular cylinder and (iii) the motion of a particle about a lifting aerofoil section. In all three cases the drag of the particle is allowed to vary with (instantaneous) Reynolds number by using an analytical approximation to the standard experimental drag-Reynolds-number relationship for spherical particles.
2,401 citations
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TL;DR: In this article, a method is presented which enables the computation of the bed-load transport as the product of the saltation height, the particle velocity and the bed load concentration.
Abstract: A method is presented which enables the computation of the bed-load transport as the product of the saltation height, the particle velocity and the bed-load concentration. The equations of motions for a solitary particle are solved numerically to determine the saltation height and particle velocity. Experiments with gravel particles (transported as bed load) are selected to calibrate the mathematical model using the lift coefficient as a free parameter. The model is used to compute the saltation heights and lengths for a range of flow conditions. The computational results are used to determine simple relationships for the saltation characteristics. Measured transport rates of the bed load are used to compute the sediment concentration in the bed-load layer. A simple expression specifying the bed-load concentration as a function of the flow and sediment conditions is proposed. A verification analysis using about 600 (alternative) data shows that about 77% of the predicted bed-load-transport rates are within 0.5 and 2 times the observed values.
1,653 citations
TL;DR: The physics of aeolian saltation, the formation and development of sand dunes and ripples, the physics of dust aerosol emission, the weather phenomena that trigger dust storms, and the lifting of dust by dust devils and other small-scale vortices are reviewed.
Abstract: The transport of sand and dust by wind is a potent erosional force, creates sand dunes and ripples, and loads the atmosphere with suspended dust aerosols This article presents an extensive review of the physics of wind-blown sand and dust on Earth and Mars Specifically, we review the physics of aeolian saltation, the formation and development of sand dunes and ripples, the physics of dust aerosol emission, the weather phenomena that trigger dust storms, and the lifting of dust by dust devils and other small-scale vortices We also discuss the physics of wind-blown sand and dune formation on Venus and Titan
1,175 citations
TL;DR: In this article, an extensive review of the physics of wind-blown sand and dust on Earth and Mars is presented, including a review of aeolian saltation, the formation and development of sand dunes and ripples, dust aerosol emission, weather phenomena that trigger dust storms, and the lifting of dust by dust devils and other small-scale vortices.
Abstract: The transport of sand and dust by wind is a potent erosional force, creates sand dunes and ripples, and loads the atmosphere with suspended dust aerosols. This paper presents an extensive review of the physics of wind-blown sand and dust on Earth and Mars. Specifically, we review the physics of aeolian saltation, the formation and development of sand dunes and ripples, the physics of dust aerosol emission, the weather phenomena that trigger dust storms, and the lifting of dust by dust devils and other small-scale vortices. We also discuss the physics of wind-blown sand and dune formation on Venus and Titan.
1,069 citations
Ferdowsi University of Mashhad1, Xi'an Jiaotong University2, King Mongkut's University of Technology Thonburi3, University of Monastir4, Shahid Beheshti University5, University of Rennes6, Clarkson University7, North Carolina State University8, University of Vermont9, Iran University of Science and Technology10, University of New South Wales11, Royal Society12, King Abdulaziz University13, Quaid-i-Azam University14, University of Tehran15, Babeș-Bolyai University16
TL;DR: A review of the latest developments in modeling of nanofluid flows and heat transfer with an emphasis on 3D simulations can be found in this paper, where the main models used to calculate the thermophysical properties of Nanofluids are reviewed.
659 citations
TL;DR: In this paper, a semi-empirical formula is developed for estimating the total amount of surface material moving in eolian saltation, surface traction, and suspension on the surface of Mars, and the ratio of final particle speed to the particle threshold friction speed is found to be several times that of saltation on earth.
Abstract: Results of low-pressure wind tunnel testing and theoretical considerations are used to estimate the eolian transport of surface material on Mars Saltation on Mars, equations of particle motion, computational results, and analytical determination of surface material movement are considered A semiempirical formula is developed for estimating the total amount of surface material moving in eolian saltation, surface traction, and suspension Numerical solutions of the equations of motion for particle trajectories on the surface of Mars are presented The ratio of final particle speed to the particle threshold friction speed is found to be several times that of saltation on earth
449 citations