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

On the quasiperiodic state in a moderate aspect ratio Taylor-Couette flow

The transition pathway leading to chaotic flow in a Taylor-Couette vessel of aspect ratio gamma=11.2 and radius ratio eta=0.81 with only the inner cylinder rotating has been studied using time-resolved particle image velocimetry. A hitherto unreported sequence of transitions, whereby the flow changes from wavy vortex flow to a quasiperiodic state of high modulation frequency, is identified using spatially resolved spectral analysis. The nature of the modulated wavy vortex flow is detailed using proper orthogonal decomposition, through which it is revealed that the modulation is similar to a fast moving azimuthal wave (FMAW). In contrast with previous observations of the FMAW at a much higher aspect ratio, the mode appears directly after wavy vortex flow and as a precursor to the CVF regime. The FMAW is also associated with codirectional vorticity fluctuations on each Taylor vortex core that diminish in strength close to the endwalls

Clinical, cultural and psychosocial impediments to self reporting of erectile dysfunction by men in Edo state, Nigeria

Introduction: Organic ED is presently considered as vasculogenic in the majority of affected middle age and elderly men and a sentinel event for cardiovascular disease. When men present with ED, it is advised that the opportunity should be used to assess their cardiovascular health.Objective: To determine the impediments to self reporting of ED and to assess the help seeking habits of men in Edo state with regards to ED. The secondary objective is to evaluate how acceptable sexual assessment is to these men when they present.Subjects and methods: This is a cross sectional study using a multi-facet, questionnaire with a section consisting of the international index of erectile function (IIEF). All men above 30 years who consented were included.Results: The response rate was 71.1%. The mean IIEF score was 20.33 with standard deviation of 4.656. The overall prevalence of ED was 51.2. Three hundred and eight of the respondents (33.3%) did not know where ED is treated, 273 (29.5%) thought that it is treated by complementary and alternative medicine practitioners while 237 (25.6) opted for the hospital as a point of care. This had a statistically significant correlation with location of the respondent (P = 0.000), level of education (P = 0.000) and senatorial zone (P = 0.000). Sexual evaluation was acceptable to 384 (41.5%) respondents when men present without ED and 757 (81.8%) when ED has occurred. This had a statistically significant correlation with level of education (P = 0.000), alcohol consumption (P = 0.000) and senatorial zone (P = 0.000).Conclusions: ED is highly prevalent in this community. Alcohol consumption, low educational level, ignorance of who and where ED is treated, location of respondent (rural) indifference, presence of co-morbidities and tribal beliefs appear to be associated with low self reporting. Affected men are more likely to patronize complementary and alternative medicine (CAM) practitioners than medical practitioners or may be out rightly indifferent. Acceptability of sexual evaluation of men is low when ED is absent and high when it has occurred.Keywords: Erectile dysfunction; Self reporting; Assessment; Acceptabilit