Influence of Shear-Thinning Rheology on the Mixing Dynamics in Taylor-Couette Flow

Non‐Newtonian rheology can have a significant effect on mixing efficiency, which remains poorly understood. The effect of shear‐thinning rheology in a Taylor‐Couette reactor is studied using a combination of particle image velocimetry and flow visualization. Shear‐thinning is found to alter the critical Reynolds numbers for the formation of Taylor vortices and the higher‐order wavy instability, and is associated with an increase in the axial wavelength. Strong shear‐thinning and weak viscoelasticity can also lead to sudden transitions in wavelength as the Reynolds number is varied. Finally, it is shown that shear‐thinning causes an increase in the mixing time within vortices, due to a reduction in their circulation, but enhances the axial dispersion of fluid in the reactor

Nonlinear Processes in Geophysics Physical simulation of resonant wave run-up on a beach

www.nonlin-processes-geophys.net/20/35/2013

Qualitative relation between reflected light intensity by Kalliroscope flakes and velocity field in the Couette?Taylor flow system

International audienceWe have used particle image velocimetry adapted to the Couette–Taylor system in order to measure the flow characteristics (axial and radial velocity components, vorticity fields, kinetic energy, etc.) and their spatio-temporal dependence. By looking for similarity between spatio-temporal diagrams of reflected light intensity and those of velocity fields, we have established that the intensity of light reflected by Kalliroscope flakes is related to the radial velocity component when the outer cylinder is fixed

Focusing wave group on a current of finite depth

Formation of freak waves resulting from the wave packets propagating in finite water depth on the background of a current is studied experimentally and numerically. In the experiment, the freak waves appear as a result of dispersion focusing of wave train excited by wave maker with modulated frequency. The space evolution of the frequency modulated train is studied in numerical simulations. We showed that in the water of finite depth, a distance of focusing increases and amplitude in the focal point decreases in comparison with infinite water depth. Experimental results are in good agreement with numerical simulations if wave breaking of surface waves does not occur

Lung Diseases Unique to Women.

The differences in the respiratory system between women and men begin in utero. Biologic sex plays a critical role in fetal development, airway anatomy, inhalational exposures, and inhaled particle deposition of the respiratory system, thus leading to differences in risk for disease, as well as clinical manifestations, morbidity, and mortality. In this article, we focus on those respiratory diseases unique to females: lymphangioleiomyomatosis and thoracic endometriosis syndrome

Laboratory Modeling of Resonance Phenomena in the Long Wave Dynamics

International audienceTwo sets of experiments in a wave flume to demonstrate resonance phenomena in laboratory conditions have been performed. The first set was performed to investigate nonlinear wave run-up on the beach. It is revealed that under certain wave excitation frequencies, a significant increase in run-up amplification is observed Ezersky et al. (Nonlin Processes Geophys 20:35, 2013, [1]). It is found that this amplification is due to the excitation of resonant mode in the region between the shoreline and wave maker. The second set of experiments was performed to model an excitation of localized mode (edge waves) by breaking waves propagating towards shoreline. It is shown that the excitation of edge waves is due to parametric instability similar to pendulum with vibrating point of suspension. The domain of instability in the plane of parameters (amplitude—frequency) of surface wave is found. It was found that for amplitude of surface wave slightly exceeding the threshold, the amplitude of edge wave grows exponentially with time, whereas for the large amplitude, the wave breaking appears and excitation of edge wave does not occur. It was shown that parametric excitation of edge wave can increase significantly (up to two times) the maximal run-up height