Hidden Equilibration Driven Losses in Whitecapping

The role of whitecapping losses of waves is investigated in a simple model based on conservation laws. It is shown that, for Airy waves, at least as much energy is lost in gradual reequilibration as is lost in the whitecapping events themselves. This model is based on the the notion that the waves and losses are small enough that some narrow spectrum of frequencies reappears over time

The Transient Neutral Flux in Plasma: An Explanation of Heating for the Solar Corona?

In this short note, we discuss a mechanism for the transport of energy, momentum and dipole moment via transient neutral carriers in plasma. This gives a way to rapidly convert bulk hydrodynamic flow energy into thermal energy over a distance of several mean free paths. In the transition region of the solar corona we estimate various processes and their potential to introduce the high energies needed to to reach the 2 x10^6K observed there. It implies that kinetic methods may be essential for modeling the corona and that there are more gentle but still robust means than reconnection to relax magnetic fields in plasmas

Inconsistencies in the Notions of Acoustic Stress and Streaming

Inviscid hydrodynamics mediates forces through pressure and other, typically irrotational, external forces. Acoustically induced forces must be consistent with arising from such a pressure field. The use of "acoustic stress" is shown to have inconsistencies with such an analysis and generally arise from mathematical expediency but poor overall conceptualization of such systems. This contention is further supported by the poor agreement of experiment in many such approaches. The notion of momentum as being an intrinsic property of sound waves is similarly found to be paradoxical. Through an analysis that includes viscosity and attenuation, we conclude that all acoustic streaming must arise from vorticity introduced by viscous forces at the driver or other solid boundaries and that calculations with acoustic stress should be replaced with ones using a nonlinear correction to the overall pressure field

Objective Nontensor Rheology: Unique Flow Decompositions from Correlated Microscopic Motions

The use of continuum mechanics and invariants built from the deviator as an adequate foundation for rheology has been recently disputed by this author. Here we give a specific example of the kind of parcel deformations that are uniquely decomposed by way of microscopic motions into a maximal rotation, a pure shear and an extension. The construction of these equations depends on only one free material parameter but they have no nice form in terms of the operations of vector and tensor calculus which may be why they were overlooked. Although the first order flow is often sufficient to give the rheological information, finite sized parcel deformations can give confusion because of boundary effects, the relevance of which are highly dependent on the global geometry of the experiment

Hidden Invariants in Rheology: The Persistent Granular Nature of Liquids

This article will use arguments derived from the deformation driven component of mixing, especially important for microfluidics, to show that the standard invariant based approaches to rheology are lacking. It is shown that the deviator, $D_{ij}$, after the process of symmetrization, loses microscopically determined information that distinguish rotation from shear and extension in a unique fashion. We recover this information through an analysis of the discrete processes that must underlie deformation driven mixing in highly correlated fluids. Without this we show there is no hope of ever deriving adequate general material parameters for rheology from microscopic dynamics. There is an unambiguous microscopic notion of the rotation rate for every parcel and we derive a general class of invariant rheological theories from it. We discuss some implications of higher order flows on solutions and suspensions including possibilities for driving and stabilization of nonuniform distributions using hydrodynamic forces alone