Critical review of the foam rheology literature

Abstract

The problem of nonlinear pseudo-steady-state parameter estimation for tubular reactors is addressed. It is shown that constant-gain, nonlinear, Kalman filters are feasible tools for estimating catalyst activity and the heat-transfer coefficient. Inclusion of a concentration measurement in addition to temperature measurements brought a large improvement in the correlation of the estimates of two parameters. An adaptation algorithm is presented to estimate one parameter for cases where process and measurement noises are unknown. It finds the optimal filter gain from data of suboptimal filter performance.

Shear-Induced “Melting” of an Aqueous Foam

“…Accordingly, Eq. [7] represents the autocorrelation function due to continuous dynamics, weighted by the fraction of light paths not yet dephased by rearrangements. A similar description has been used for studying constrained dynamics within a polymer gel, where the removal of light paths was accomplished by translating the sample through the incident beam (37).…”

“…Foam rheology data have long been analyzed in terms of y and the "plastic viscosity" p ϭ y d , though with varying degrees of rigor (7). The values of y and d must ultimately be understood in terms of the microscopic, bubble-scale, structure and dynamics of the foam.…”

Rheology of colloidal gas aphrons (microfoams) made from different surfactants

“…Microfoam was treated as a pseudo-homogeneous timeindependent non-Newtonian fluid. The pipe diameter was much larger than the bubble size so that CGA could be treated as a continuous medium [23,24]. Previous studies with stainless steel pipes of various diameter shows that the slip velocity was zero at the wall [1,22].…”

Nonlinear Bubble Dynamics in a Slowly Driven Foam

“…As a form of matter, foams exhibit remarkable mechanical properties that arise from this structure in ways that are not well understood. Namely, foams can support static shear stress, like a solid, but can also How and deform arbitrarily, like a liquid, if the applied stress is sufficiently large [3,4].…”