On Shear-Driven Ventilation of Snow

Bounds on Surface Stress-Driven Shear Flow

The background method is adapted to derive rigorous limits on surface speeds and bulk energy dissipation for shear stress driven flow in two and three dimensional channels. By-products of the analysis are nonlinear energy stability results for plane Couette flow with a shear stress boundary condition: when the applied stress is gauged by a dimensionless Grashoff number Gr, the critical Gr for e...

Shear-driven overturns

Fracture toughness of snow in shear under friction.

The fracture toughness of snow in shear is one of the most relevant parameters when studying the mechanics of snow slab avalanche release. Double-cantilever snow beams were loaded asymmetrically to determine K(IIc). If crack surfaces touch under applied pressure, the fracture toughness in shear of snow (rho=247 kg m(-3)) is K(IIc)=680+/-60 Pa m(1/2). Screening of the stress intensity at the cra...

Ventilator-driven xenon ventilation studies.

A modification of a common commercial Xe-133 ventilation device is described for mechanically assisted ventilation imaging. The patient's standard ventilator serves as the power source controlling the ventilatory rate and volume during the xenon study, but the gases in the two systems are not intermixed. This avoids contamination of the ventilator with radioactive xenon. Supplemental oxygen and...

On the scaling of shear-driven entrainment: a DNS study

The deepening of a shear-driven turbulent layer penetrating into a stably stratified quiescent layer is studied using direct numerical simulation (DNS). The simulation design mimics the classical laboratory experiments by Kato & Phillips (J. Fluid Mech., vol. 37, 1969, pp. 643–655) in that it starts with linear stratification and applies a constant shear stress at the lower boundary, but avoids...