199 research outputs found
Analysis of the characteristic lengths in the bubble and slug flow regimes generated in a capillary T-junction
We present an analysis of the geometry of the continuous and disperse phases in the bubble and slug flow regimes in air–water mixtures generated in a capillary T-junction of 1 mm internal diameter. Bubble size dispersion is very low in the considered flow patterns. The concept of unit cell is used to identify two characteristic lengths of the two-phase flow, namely, the unit cell length and the bubble length. The relationship between these lengths and the gas and liquid superficial velocities, gas mean velocity, bubble generation frequency and volume average void fraction is analysed. We conclude that in the considered
configuration the unit cell and bubble lengths can be predicted either by the ratio of the gas–liquid
superficial velocities or the volume average void fraction.Peer ReviewedPreprin
Experimental analysis of the bubble-slug transition in a minichannel in microgravity conditions
Best student presentation in Physical SciencePeer ReviewedAward-winnin
Characterization of bubbly and slug flow regimes generated in a minichannel in microgravity conditions
We performed a characterization of the bubbly and slug flow regimes in minichannels in conditions
relevant to microgravity. Two-phase flows were generated on ground by means of a T-junction device
(1 mm i.d.), whose operation is independent to changes in gravity level [1]. Air and water were injected
at several superficial velocities ranging from 0 up to 2 m/s. The generation and detachment of the
minibubbles is provided by the liquid cross-flow (see figure). In nominal conditions small Bond and
Weber numbers are achieved for the air/water mixture flow. Therefore, capillary forces dominate over
buoyancy and inertial forces [2]. Laminar regime can also be assumed. Bubbly, slug, churn and
annular flows were observed (see figure). The characterization consists in the analysis of the bubble
and the unit cell lengths, the bubble velocity and the void fraction in both bubbly and slug flow
regimes.Peer Reviewe
Bubble and slug flows characteristic lengths in a microchannel
Peer ReviewedPostprint (published version
Comparison of two methods for generating small bubbles in microgravity conditions
Peer ReviewedPostprint (published version
Comparison of two methods for generating small bubbles with a T-junction in microgravity conditions
Peer ReviewedPostprint (published version
The Protection Motivation Theory as a Predictor of the Use of Protective Behavioral Strategies among Young Adults
Alcohol Protective Behavioral Strategies (PBS) have shown to be effective in minimizing alcohol-related negative consequences. However, previous studies on the explanatory factors of PBS use are scarce. The Protection Motivation Theory (PMT) is a social cognition theory which attempts to explain intention to use protective behaviors in respond to health threats such as alcohol-related negative consequences. According to PMT, the likelihood of engaging in protective behaviors when facing a threat is a product of two processes: threat appraisal (perceived severity and perceived vulnerability to the threat) and coping appraisal (response efficacy and perceived self-efficacy for using a protective behavior). We examined the predictive utility of the PMT on the intention to use PBS related to the Manner of Drinking (MOD) among a community sample of young adults. Prospective study that recruited 360 young adults aged 18-24 years by targeted sampling procedure (Mage=21.15 [SD=2.23]; female=50.3%). Most baseline participants (94.2%, n=339) completed a 2-months follow-up assessment. Perceived severity and perceived vulnerability to alcohol use, perceived efficacy of MOD strategies to reduce alcohol-related negative consequences, and self-efficacy to engage in MOD strategies were measured at baseline, and intention to use MOD strategies at follow-up. A multiple lineal regression model for predicting intention to use MOD strategies was used. Perceived severity (β=.13, p=.017), response efficacy (β=.270, p<.001), and selfefficacy (β=.240, p<.000) were positively associated with high intention to use MOD protective strategies. In line with previous research, our findings demonstrated that coping-appraisal components of PMT are more explanatory of protective behaviors than threat-appraisal components. These results may be useful to inform interventions aimed at increasing PBS use among young adults.Fil: González Ponce, Bella. Universidad de Huelva; EspañaFil: Carmona Márquez, JosĂ©. Universidad de Huelva; EspañaFil: Vera, BelĂ©n del Valle. Universidad Nacional de CĂłrdoba. Instituto de Investigaciones PsicolĂłgicas. - Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - CĂłrdoba. Instituto de Investigaciones PsicolĂłgicas; ArgentinaFil: Pautassi, Ricardo Marcos. Universidad Nacional de CĂłrdoba. Facultad de PsicologĂa; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - CĂłrdoba. Instituto de InvestigaciĂłn MĂ©dica Mercedes y MartĂn Ferreyra. Universidad Nacional de CĂłrdoba. Instituto de InvestigaciĂłn MĂ©dica Mercedes y MartĂn Ferreyra; ArgentinaFil: Fernández CalderĂłn, FermĂn. Universidad de Huelva; España17th European Congress of PsychologyLiublianaEslovenialovenian Psychologists’ Associatio
Characterization of the performance of an injector for the controlled generation of microbubbles
We perform a characterization of a recently reported microbubble injector in conditions relevant to microgravity. Injection
of bubbles is based on the generation of a slug flow in a capillary T-junction, whose operation is robust to changes in the
gravity level. We address questions regarding the performance under different working regimes. In particular, we focus on
the regimes found within a large range of gas and liquid injection flow rates. The injection performance is characterized
by measuring bubble generation frequency. We propose curves obtained empirically for the behavior of generation
frequency and crossover between regimes.Peer Reviewe
Characterization of the performance of an injector for the generation of controlled microbubbles
Peer Reviewe
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