[1] Using three-dimensional (3-D) instantaneous dynamic models of the Central Aleutian subduction zone, we show that a low viscosity, low density (dr = 10 kg/m) region in the wedge is needed to match observations of topography, the geoid and the stress-state in the slab and overriding plate. Previous models of the Tonga-Kermadec subduction zone also require a low viscosity, low density (dr = 20...

In this thesis I address the topic of anisotropy – the directional dependence of physical properties of rocks – from two complementary angles: I use seismic anisotropy to detect deformation in the mantle, and I demonstrate the importance of accounting for rheological anisotropy in mantle flow models. The observations of seismic anisotropy in the Earth’s interior allow geophysicists to probe the...

[1] Density variations due to changes in bulk chemistry in the lowermost mantle play an important role in the dynamics and chemistry of plumes. In this study we perform a series of high-resolution numerical experiments in an axisymmetric spherical shell to systematically investigate the formation of plumes from a thermochemical boundary layer and the entrainment of the dense material by plumes....

Layered viscosity, temperature-dependent viscosity, and surface plates have an important effect on the scale and morphology of structure in spherical models of mantle convection. We find that long-wavelength structures can be produced either by a layered viscosity with a weak upper mantle or temperature-dependent viscosity even in the absence of surface plates, corroborating earlier studies. Ho...

In this paper hemodynamic wall parameters which play an important role to diagnose arterial disease were studied and compared for three different rheology models (Newtonian, Power law and Quemada). Also because of the pulsatile behavior of blood flow the results were obtained for three Womersley numbers which represent the frequencies of the applied pulses. Results show that Quemada model alway...

S U M M A R Y On Earth, oceanic plates subduct beneath a variety of overriding plate (OP) styles, from relatively thin and negatively buoyant oceanic OPs to thick and neutrally/positively buoyant continental OPs. The inclusion of an OP in numerical models of self-consistent subduction has been shown to reduce the rate that subducting slabs roll back relative to the equivalent single plate model...

We investigate the relaxation of internal temperature and the concept of volume viscosity in nonequilibrium gas models derived from the kinetic theory. We first investigate a nonequilibrium gas model with two temperatures—translational and internal—where the volume viscosity is absent. We establish that, in a relaxation regime, the temperature difference becomes proportional to the divergence o...

[1] The effect of rheology on the evolution of the slab-tip during subduction initiation is analyzed using 2-D numerical flow models. Experimentally determined flow laws have both strong temperatureand stress-dependence, which leads to large local variations in viscosity with direct consequences for subduction initiation. We find that models with Newtonian viscosity lead to flat or coupled subd...

A 2.4-year controlled-cooling-rate experiment was carried out to investigate the dependence of hydrous species concentrations in rhyolitic melt on cooling rate. The experiment allows us to obtain speciation for a cooling rate of 1.68 · 10 6 K/s, extending previous experimental data by two orders of magnitude. Furthermore, a viscosity as high as 10 Pa s is inferred for this hydrous rhyolitic mel...

Two-dimensional models of layered protoplanetary discs – II. The effect of a residual viscosity in the dead zone. ABSTRACT We study axisymmetric models of layered protoplanetary discs taking radiative transfer effects into account, and allowing for a residual viscosity in the dead zone. We also explore the effect of different viscosity prescriptions. In addition to the ring instability reported...