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## Publications

Publications (26)

Cave propagation is a complex process due to interacting variables including mine geometry, rock mass heterogeneity and complex structural networks and stress fields. The Ernest Henry sub-level cave (SLC) is directly below an open pit which provided an opportunity to observe and measure rock mass failure as the cave initiated and propagated through...

Rarefied gas flows generated by resonating nanomechanical structures pose a significant challenge to theoretical analysis and physical interpretation. The inherent noncontinuum nature of such flows obviates the use of classical theories, such as the Navier-Stokes equations, requiring more sophisticated physical treatments for their characterization...

The Ernest Henry crusher chamber is a large excavation located at a depth of approximately 1 km. During
the pre-feasibility study, a single exploration drill hole was extended below the orebody which identified no
adverse ground conditions and the crusher location was set. Additional diamond drilling into the planned
crusher chamber location was co...

Open access to forecasts of mine geotechnical performance in the form of open databases of model results has been considered risky in the past, with a concern that the results will not be understood or will be misused. However, some modelling techniques allow very high similitude modelling of mine deformation and the results can be presented as def...

Open pit blasting at Ernest Henry Mining has the potential to cause damage to nearby underground workings. This paper is a case study of the blast vibration management project that was conducted to ensure open pit blasting did not adversely affect the stability of upper production levels or cause damage to the underground primary fan units. The two...

Fully coupled, 3d discontinuum, hydromechanical simulation is becoming more commonplace for mine based and oil and gas geotechnical problems. The focus of simulation for the two industries overlaps, but is balanced differently: mining focuses more often on deformation and damage and has opportunities for calibration at a high resolution, while oil...

It has long been known that: the thickness [Delta] of a plane 1D shock, expressed in terms of the mean free path [lambda_1] in the upstream (pre-shock) flow, is a strong function of shock Mach number; and that the form of this function is sensitive to the form of the viscosity law [mu = mu(T)] of the gas. On the other hand, the approximate kinetic...

The generalized hard sphere (GHS) collision model was introduced by Hash and Hassan (1993). It is a generalization of the Sutherland collision model proposed by Kuscer (1989). At low temperatures, where the attractive intermolecular forces are important, the GHS collision model produces a more accurate variation of viscosity with temperature than t...

Spacecraft entry into the atmosphere of a planet requires protection against the extreme temperatures that result from aerodynamic heating. This is normally achieved through use of a heat shield, which also provides the necessary aerodynamic braking and stability. The shape of the heat shield used varies considerably between spacecraft, and spheric...

The macroscopic chemistry method [Lilley and Macrossan, Phys. Fluids, v16, p2054, 2004] was developed to model non-equilibrium chemically reacting flows with the direct simulation Monte Carlo (DSMC) method. The macroscopic method uses kinetic temperatures, calculated from mean particle energies, to calculate reaction rates. For strongly non-equilib...

A study was conducted to demonstrate the use of blunted-cone heat shields to control extreme temperatures generated by spacecrafts during atmospheric entry. The device protected the craft from the high temperatures and provided the necessary braking and stability for controlled entry through the atmosphere. The calculus of variations was used to sh...

Flow of a dilute gas near a solid surface exhibits non-continuum effects that are manifested in the Knudsen layer. The non-Newtonian nature of the flow in this region has been the subject of a number of recent studies suggesting that the so-called 'effective viscosity' at a solid surface is half that of the standard dynamic viscosity. Using the Bol...

Rarefied gas flow modeling presents significant challenges in the characterization of nanoscale devices and their applications. An important feature of such flows is the Knudsen layer, which is known to exhibit non-Newtonian viscosity behavior. Significantly, recent research has suggested that the effective viscosity at the surface is about half th...

We present a new scheme for modeling rotational energy exchange with the direct simulation Monte Carlo (DSMC) method. The new scheme is fundamentally different from conventional Borgnakke-Larsen (BL) procedures, in which energy exchange is performed at the time of collision. In the new scheme, all collisions are performed elastically. Rotational en...

We test the recently developed macroscopic approach to modeling chemistry in DSMC, by simulating the flow of rarefied dissociating nitrogen over a blunt cylinder. In this macroscopic method, chemical reactions are decoupled from the collision routine. Molecules are chosen to undergo dissociation at each time step, after the collisions are calculate...

In most chemistry methods developed for the direct simulation Monte Carlo (DSMC) technique, chemical reactions are computed as an integral part of the collision simulation routine. In the macroscopic chemistry method developed here, the simulation of collisions and the simulation of reactions are decoupled; reactions are computed independently, aft...

Mott-Smith’s kinetic theory of shock structure [Phys. Rev. 82, 885 (1951); C. Muckenfuss, Phys. Fluids 5, 1325 (1962)] suggests that, for any intermolecular potential, the average number of collisions undergone by a molecule as it crosses the shock approaches a limit as the Mach number increases. We check this with direct simulation Monte Carlo cal...

In the direct simulation Monte Carlo (DSMC) method for simulating rarefied gas flows, the velocities of simulator particles that cross a simulation boundary and enter the simulation space are typically generated using the acceptance-rejection method that samples the velocities from the theoretical velocity distribution. This paper analyses an alter...

The generalised hard sphere collision model (GHS) was introduced by Hassan and Hash [Physics of Fluids A, v5(3), 738-744 (1993)] and is a generalization of the Sutherland collision model suggested by Kuscer [Physica, v158, 784-800 (1989)]. Despite its superior modelling of realistic gas viscosities, compared to the Variable Hard Sphere collision mo...

This report presents some details of a molecular model for use in DSMC simulations that reproduces the Sutherland viscosity relation. This Sutherland model gives poor computational efficiency, due to the existence of extremely large collision cross-sections at low collision speeds. A modified version of the Sutherland model is therefore introduced...

The macroscopic chemistry method for modelling non-equilibrium reacting gas flows with the direct simulation Monte Carlo (DSMC) method is developed and tested. In the macroscopic method, the calculation of chemical reactions is decoupled from the DSMC collision routine. The number of reaction events that must be performed in a cell is calculated wi...