Following Blumenthal et al. 1] and Piran et al. 2] I discuss a simple model for the gravitational formation of voids. This model enables us to estimate the primordial perturbation required on the scale of voids. A comparison of this condition with the constraints on the spectrum of uctuations derived from CMBR observations reveals that gravitational growth of large voids require more power on t...

-The paper is concerned with the flow of dispersions of gas bubbles in liquid, with bubble sizes such that the inertia forces on the bubbles are of importance to the dynamics. One-dimensional conservation equations are derived, which govern the flow when the deviations from the uniform state are small. These are used to describe the features of the propagation of void fraction disturbances, and...

The parametric resonance of the axial vibrations of a cantilever pipe conveying harmonically perturbed two-phase flow is investigated using the method of multiple scale perturbation. The nonlinear coupled and uncoupled planar dynamics of the pipe are examined for a scenario when the axial vibration is parametrically excited by the pulsating frequencies of the two phases conveyed by the pipe. Aw...

The formation of plate tectonics from mantle convection necessarily requires nonlinear rheological behavior. Recent studies suggest that self-lubricating rheological mechanisms are most capable of generating plate-like motion out of fluid flows. The basic paradigm of self-lubrication is nominally derived from the feedback between viscous heating and Ž temperature-dependent viscosity. Here, we p...

In a stress state dominated by shear, pre-existing voids rotate, elongate, and close up to form micro-cracks, which interact through void coalescence eventually may cause complete loss of load-carrying capacity. The mechanism sets apart in shear from that under tensile-dominated states, the present work demonstrates gradient strengthening affects macroscopic strain at onset plastic flow localiz...

We apply the HotQC method of Kulkarni et al. (J Mech Phys Solids 56:1417–1449, 2008) to the study of quasistatic void growth in copper single crystals at finite temperature under triaxial expansion. The void is strained to 30% deformation at initial temperatures and nominal strain rates ranging from 150 to 600K and from 2.5×105 to 2.5×1011 s−1, respectively. The interatomic potential used in th...