Jose Antonio Mancera Gordillo - Academia.edu (original) (raw)
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Papers by Jose Antonio Mancera Gordillo
Arquivos Brasileiros de Cardiologia, 2007
To translate, to make the cultural adaptation and to evaluate reproducibility and validity of the... more To translate, to make the cultural adaptation and to evaluate reproducibility and validity of the Portuguese version of the AQUAREL (Assessment of QUAlity of life and RELated events) questionnaire, which is a specifi c tool to assess quality of life in pacemaker patients.
Physical Review Letters, 2009
A circular disc impacting on a water surface creates a remarkably vigorous jet. Upon impact an ax... more A circular disc impacting on a water surface creates a remarkably vigorous jet. Upon impact an axisymmetric air cavity forms and eventually pinches off in a single point halfway down the cavity. Immediately after closure two fast sharp-pointed jets are observed shooting up-and downwards from the closure location, which by then has turned into a stagnation point surrounded by a locally hyperbolic flow pattern. This flow, however, is not the mechanism feeding the two jets. Using high-speed imaging and numerical simulations we show that jetting is fed by the local flow around the base of the jet, which is forced by the colliding cavity walls. Based on this insight, we then show how the analytical description of a collapsing void (using a line of sinks along the axis of symmetry) can be continued beyond the time of pinch-off to obtain a quantitative model for jet formation which is in good agreement with the numerical and experimental data. 47.55.df, 47.11.Hj The most prominent phenomenon when a solid object hits a water surface is the high-speed jet shooting upwards into the air. The basic sequence of events leading to this jet has been studied since Worthington more than a century ago: After impact, the intruder creates an air-filled cavity in the liquid which due to hydrostatic pressure immediately starts to collapse, eventually leading to the pinch-off of a large bubble. Two very thin jets are ejected up-and downwards from the pinch-off point which constitutes a finite-time singularity intensively studied in recent time . Such singularities have been shown to lead to a hyperbolic flow pattern after collapse and thus to the formation of liquid jets .
Physical Review Letters, 2008
Cylindrical liquid jets are inherently unstable and eventually break into drops due to the Raylei... more Cylindrical liquid jets are inherently unstable and eventually break into drops due to the Rayleigh-Plateau instability, characterized by the growth of disturbances that are either convective or absolute in nature. Convective instabilities grow in amplitude as they are swept along by the flow, while absolute instabilities are disturbances that grow at a fixed spatial location. Liquid jets are nearly always convectively unstable. Here we show that two-phase jets can breakup due to an absolute instability that depends on the capillary number of the outer liquid, provided the Weber number of the inner liquid is >O1. We verify our experimental observations with a linear stability analysis.
Arquivos Brasileiros de Cardiologia, 2007
To translate, to make the cultural adaptation and to evaluate reproducibility and validity of the... more To translate, to make the cultural adaptation and to evaluate reproducibility and validity of the Portuguese version of the AQUAREL (Assessment of QUAlity of life and RELated events) questionnaire, which is a specifi c tool to assess quality of life in pacemaker patients.
Physical Review Letters, 2009
A circular disc impacting on a water surface creates a remarkably vigorous jet. Upon impact an ax... more A circular disc impacting on a water surface creates a remarkably vigorous jet. Upon impact an axisymmetric air cavity forms and eventually pinches off in a single point halfway down the cavity. Immediately after closure two fast sharp-pointed jets are observed shooting up-and downwards from the closure location, which by then has turned into a stagnation point surrounded by a locally hyperbolic flow pattern. This flow, however, is not the mechanism feeding the two jets. Using high-speed imaging and numerical simulations we show that jetting is fed by the local flow around the base of the jet, which is forced by the colliding cavity walls. Based on this insight, we then show how the analytical description of a collapsing void (using a line of sinks along the axis of symmetry) can be continued beyond the time of pinch-off to obtain a quantitative model for jet formation which is in good agreement with the numerical and experimental data. 47.55.df, 47.11.Hj The most prominent phenomenon when a solid object hits a water surface is the high-speed jet shooting upwards into the air. The basic sequence of events leading to this jet has been studied since Worthington more than a century ago: After impact, the intruder creates an air-filled cavity in the liquid which due to hydrostatic pressure immediately starts to collapse, eventually leading to the pinch-off of a large bubble. Two very thin jets are ejected up-and downwards from the pinch-off point which constitutes a finite-time singularity intensively studied in recent time . Such singularities have been shown to lead to a hyperbolic flow pattern after collapse and thus to the formation of liquid jets .
Physical Review Letters, 2008
Cylindrical liquid jets are inherently unstable and eventually break into drops due to the Raylei... more Cylindrical liquid jets are inherently unstable and eventually break into drops due to the Rayleigh-Plateau instability, characterized by the growth of disturbances that are either convective or absolute in nature. Convective instabilities grow in amplitude as they are swept along by the flow, while absolute instabilities are disturbances that grow at a fixed spatial location. Liquid jets are nearly always convectively unstable. Here we show that two-phase jets can breakup due to an absolute instability that depends on the capillary number of the outer liquid, provided the Weber number of the inner liquid is >O1. We verify our experimental observations with a linear stability analysis.