Vortices catapult droplets in atomization

International audienceA droplet ejection mechanism in planar two-phase mixing layers is examined. Any disturbance on the gas-liquid interface grows into a Kelvin-Helmholtz wave, and the wave crest forms a thin liquid film that flaps as the wave grows downstream. Increasing the gas speed, it is observed that the film breaks up into droplets which are eventually thrown into the gas stream at large angles. In a flow where most of the momentum is in the horizontal direction, it is surprising to observe these large ejection angles. Our experiments and simulations show that a recirculation region grows downstream of the wave and leads to vortex shedding similar to the wake of a backward-facing step. The ejection mechanism results from the interaction between the liquid film and the vortex shedding sequence: a recirculation zone appears in the wake of the wave and a liquid film emerges from the wave crest; the recirculation region detaches into a vortex and the gas flow over the wave momentarily reattaches due to the departure of the vortex; this reattached flow pushes the liquid film down; by now, a new recirculation vortex is being created in the wake of the wave--just where the liquid film is now located; the liquid film is blown up from below by the newly formed recirculation vortex in a manner similar to a bag-breakup event; the resulting droplets are catapulted by the recirculation vortex

Hydrogen blending effect on fiscal and metrological instrumentation: A review

A green hydrogen (H2) economy requires a sustainable, efficient, safe, and widespread infrastructure for transporting and distributing H2 from production to consumption sites. Transporting a hydrogen/natural gas (H2NG) mixture, including pure H2, through the existing European natural gas (NG) infrastructure is considered a cost-effective solution, particularly in the transitional phase. Several reasons justify the H2NG blending option. The NG infrastructure can be efficiently repurposed to transport H2, by blending H2 with NG, to operate as H2 daily storage, matching production and demand and to enable large-scale seasonal H2 storage. Although many benefits exist, the potential of existing NG grids for transporting and distributing green H2 may face limitations due to technical, economic, or normative concerns. This paper focuses on the state of the art of the European NG transmission and distribution metrology normative framework and identifies the gaps to be filled in case of H2NG flowing into the existing grids. The paper was revised to provide a comprehensive analysis of the practical implications resulting from the H2NG blend option

Aetiological factors and perception of anaemia in Tunisian women of reproductive age

OBJECTIVES: To identify aetiological factors in anaemia and to explore knowledge, perceptions and attitudes towards anaemia. DESIGN: Two cross-sectional surveys and sixteen focus group discussions. SETTING: The two regions with the highest prevalence of anaemia in Tunisia, Greater Tunis (GT) and the South West (SW). SUBJECTS: Two representative samples of 687 (GT) and 729 (SW) women of reproductive age; 108 women were included in focus group discussions. RESULTS: Among anaemic women, 63.4% in the GT region and 80.2% in the SW displayed iron deficiency (ID). Genetic haemoglobinopathies accounted for 10.0% and 3.6% of the cases of anaemia in the two regions, respectively. After adjustment for confounders, the major factors for iron-deficiency anaemia were low dietary Fe intake (OR = 5.0, 95% CI 3.0, 8.4), drinking tea after eating (OR = 3.4, 95% CI 2.0, 5.7) and pica (OR = 2.1, 95% CI 1.1, 3.9). Most of the women related anaemia to the following causes: malnutrition, lack of hygiene, and their heavy workload and responsibilities in the household. Many women connected anaemia with hypotension. Few established a relationship between ID and anaemia. They had confidence in their doctor for treatment, but many complained they were not given sufficient information. Low dietary Fe intake, inappropriate food practices and inadequate perceptions contribute to the aetiology of anaemia in women. CONCLUSIONS: These results point out to the need for a strategy combining food fortification, Fe supplementation for pregnant women, nutritional education for the general public and at-risk specific target groups, and training of health professionals

Post‐HCV cure self‐reported changes in physical activity, eating behaviours, and fatigue in people living with HIV (ANRS CO13 HEPAVIH)

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