Showing papers by "James D. Iversen published in 1986"
01 Jan 1986
TL;DR: In this article, the Amboy lava field in the Mojave Desert affords the opportunity for the study of aeolian processes in a volcanic terrain, and the surface roughness of the pahoehoe lavas has a pronounced effect on the atmospheric boundary layer and increases the threshold velocity.
Abstract: The Amboy lava field in the Mojave Desert affords the opportunity for the study of aeolian processes in a volcanic terrain. Atmospheric experiments show that the surface roughness of the pahoehoe lavas has a pronounced effect on the atmospheric boundary layer and increases the threshold velocity. Experiments also show that the presence of the Amboy cinder cone generates a zone of atmospheric turbulence that keeps the surface swept free of particles in the wake of the cone. Wind tunnel simulations compare well with field measurements and enable data to be obtained for other parts of the lava flow not studied in the field.
22 citations
01 Jan 1986
TL;DR: The environmental wind tunnel is a useful tool for simulating atmospheric winds near the Earth's surface and their effects as discussed by the authors, and has been used to determine surface pressure on, and flow patterns around buildings and other boundary layer obstructions.
Abstract: The environmental wind tunnel is a useful tool for simulating atmospheric winds near the Earth’s surface and their effects. It has been used to determine surface pressure on, and flow patterns around buildings and other boundary layer obstructions. Several wind tunnels have been constructed for modeling saltation phenomena, i.e., blowing sand and snow at small scale.
2 citations
01 Jan 1986
TL;DR: In this article, the effect of non-erodible roughness on threshold is discussed as well as the physics of threshold of particle motion due to an atmospheric vortex (dust devil).
Abstract: Observations of dust storms on Mars via telescope and spacecraft have led to new investigations and understanding of particle threshold phenomena. Wind tunnel testing with particles of different density and with atmospheric pressure down to the level of the Martian surface (500 Pa), has led to improved formulations for threshold prediction, including better understanding of the effects of particle cohesion. The effect of nonerodible roughness on threshold is discussed as well as the physics of threshold of particle motion due to an atmospheric vortex (dust devil).
1 citations
01 Jan 1986
TL;DR: In this paper, the effects of aerodynamic roughness in saltation, mass transport rate, and particle equations of motion are used to simplify the similitude requirements for modeling saltation phenomena at small scale.
Abstract: The similitude requirements for modeling saltation phenomena at small scale are exceedingly complex. This paper reviews the basic dimensionless parameters and how theoretical means, namely the effects of aerodynamic roughness in saltation, mass transport rate, and the particle equations of motion are used to group the basic parameters and thus somewhat simplify the similitude problem. Two examples illustrate the use of mass transport rate and roughness parameters to correlate model data.