1,723,050 research outputs found
The marriage record of Rendoza, Esteban Luis Jorge and Ramirez, Maria Josefa Garcia
No full textMarriage license for Maria Josefa Garcia Ramirez and Esteban Luis Jorge Rendoza. Ph. de Carriere was the officiant
Dynamics of non-spherical particles in turbulence
No full textRecent experimental and numerical investigations have enabled researchers to study directly the 3D time dependent motion of spherical and quasi-spherical particles in quiescent and turbulent flows. At the same time, fibre-like particles have been also extensively investigated during the last decades due to the high relevance of these geometries in the process industries. Although these studies have permitted the scientific community to understand several scenarios, the influence of turbulence on the settling dynamics of large, inertial, planar particles remains to be understood; and this represents not only an interesting research problem in itself but also a useful tool to optimize industrial processes, as for the case of Aquavitrum Ltd. To tackle this problem we first extended the work carried for disks falling under the fluttering mode, but to other planar geometries. We found several modes of secondary motion for n-sided polygons falling in quiescent fluid that are associated with the particle dimensionless inertia and Reynolds number. We also measured the wake behind these particles and identified strong differences associated with their falling style. Other variations of disk-like particles with wavy-edge were investigated and drag correlations based on the particle geometry obtained. We also proposed a one-equation simple pendulum model to capture precisely the complete trajectory of the particle as long as the three dimensional state of the trajectory remains moderate. Then, a random jet array facility to generate turbulence was built and two turbulence states were investigated. First, we focused on the homogeneity of the stationary state to later investigated the temporal decay of turbulent kinetic energy. We observed an overall enhancement of the decay rate as compare with previous studies and found that this was caused due to turbulent confinement. Finally, the fall of inertial disks was investigated under the effect of background turbulence. We observed severe differences on the falling style of disks as compared with the quiescent case. We also found that the mean descent velocity of the particles was enhanced for the configurations tested and this was inversely correlated with the frequency of the oscillatory motion. Last, we measured particle dispersion and found the the radial position of the particles can be well captured with lognormal distributions
“EL TLAXQUICHE, EL GUARDIÁN DE LA MONTAÑA” ESTEBAN LUIS SORIANO ESCOBAR
Full text linkEsta frase es aplicable a Esteban Luis Soriano que murió físicamente, pero que ha dejado un recuerdo imborrable. Ejemplo para las nuevas generaciones, nos muestran el quehacer de aquellos que teniendo un espíritu indomable trascienden más allá de lo que la sociedad exige para los demás.
Narrar su permanencia en la tierra no es fácil, ya que seguramente se quedan sin mencionar aspectos importantes que dejando huella, pudieran ser invocados por quienes lo vivieron. Básteme entonces presentar el perfil de un personaje de leyenda que no tiene edad, porque aquellos que ofrendan su vida en el servicio a los demás, conservan su espíritu y caminan al lado de los inmortales
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Disks settling in turbulence
No full textThis paper describes an experimental investigation of the dynamics of freely falling thin circular disks settling through turbulence. The patterns of the three dimensional disk motion are studied using an orthogonal arrangement of two high speed cameras. Turbulence is generated in a water tank using a random jet array facility where the jets are mounted in a co-planar configuration. The facility is run continuously until turbulence reaches a statistically stationary state, then, all water pumps are turned off simultaneously and a disk is released after a given waiting time. Contrary to spherical particles, finite-size inertial disks show an increase in the descent velocity for turbulence velocity fluctuations smaller than the particle descent velocity in quiescent flow. Thus, we observe a severe increase of the mean descent velocity of the disk with increasing the magnitude of the turbulence velocity fluctuations (up to of the velocity in quiescent flow for the disk with higher dimensionless inertia ). We also observe descent events that do not exist for disks falling in still fluid; i.e. `slow tumbling' events and `levitating' events. Finally, we show that the dominant frequency of the particle oscillatory motion decreases for increasing descent velocity and that particles exhibit oscillatory frequencies that never exceed the dominant frequency in quiescent flow in more than
Three dimensional wakes of freely falling planar polygons
No full textThe wake characteristics of various thin particles with identical material properties but different frontal geometries (disks, hexagonal plates and square plates) are examined by means of three dimensional measurements of the instantaneous velocity field. The reference particle is a circular disk that lies within the Reynolds number—dimensionless moment of inertia domain (Re- I∗) corresponding to the fluttering regime, as defined by Willmarth et al. (Phys Fluids 7:197–208, 1964). Hexagonal and square plates are manufactured to have the same frontal area and material properties of the reference particle. Three dimensional trajectories obtained from high-speed imaging show that disks preferably adopt a quasi-2D oscillatory descent; i.e. ‘planar zig-zag’, whereas particles with less circularity adopt three dimensional trajectories more frequently; i.e. ‘transitional’ and ‘spiral’ descent. The wake behind free-falling disks is found to be a succession of hairpin vortices shed off at every turning point linked by a pair of counter rotating vortices that grow downstream from the leading edge of the disk. In contrast, square plates describing ‘spiral’ descent show an almost time-independent wake morphology with large-scale vortex shedding around the entire perimeter of the particle. The large-scale wake structures of hexagonal plates resemble either the disks’ or the squares’ depending on the falling regime that they adopt. Finally, we compare the dimensionless vorticity distribution in the wake of the particles and found that this also depends on the falling style that the particle adopts during the descent.</p
Dataset for Edge effects on the fluttering characteristics of freely falling planar particles
No full textData supporting the paper 'Edge effects on the fluttering characteristics of freely falling planar particles' by Luis Blay Esteban, John Shrimpton, and Bharathram Ganapathisubramani, Physical Review Fluids (2018). This data include the X-Y-Z coordinates of sections of particle trajectories freely falling in water for the reproduction of the figures in the paper.
The Matlab script ‘FigureGeneration.m’ creates the figures for which there is not sufficient data in the paper to be reproduced. The functions circle2.m and circlefit3d.m where used to generate some of the results presented in the paper and are included in this dataset.
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Laboratory experiments on the temporal decay of homogeneous anisotropic turbulence
No full textWe experimentally investigate the temporal decay of homogeneous anisotropic turbulence,
monitoring the evolution of velocity fluctuations, dissipation and turbulent length
scales over time. We employ an apparatus in which two facing random jet arrays of
water pumps generate turbulence with negligible mean flow and shear over a volume
that is much larger than the initial characteristic turbulent large scale of the flow. The
Reynolds number based on the Taylor microscale for forced turbulence is Reλ ≈ 580 and
the axial-to-radial ratio of the root mean square velocity fluctuations is 1.22. Two velocity
components are measured by particle image velocimetry at the symmetry plane of the
water tank. Measurements are taken for both ‘stationary’ forced turbulence and natural
decaying turbulence. For decaying turbulence, power-law fits to the decay of turbulent
kinetic energy reveal two regions over time; in the near-field region (t/tL < 10, tL is
the integral time scale of the forced turbulence) a decay exponent m ≈ −2.3 is found
whereas for the far-field region (t/tL > 10) the value of the decay exponent was found to
be affected by turbulence saturation. The near-field exhibits features of non-equilibrium
turbulence with constant L/λ and varying C (dissipation constant). We found a decay
exponent m ≈ −1.4 for the unsaturated regime and m ≈ −1.8 for the saturated regime,
in good agreement with previous numerical and experimental studies. We also observe a
fast evolution towards isotropy at small scales, whereas anisotropy at large scales remains
in the flow over more than 100 tL. Direct estimates of dissipation are obtained and the
decay exponent agrees well with the prediction m = m−1 throughout the decay process
Study of the circularity effect on drag of disk-like particles
No full textThis paper presents a study of the terminal fall velocity, drag coefficient and descent style of ‘wavy-edge’ flat particles. Being highly non-spherical and with a size of up to a few centimetres, these particles show strong self-induced motions that lead to various falling styles that result in distinct drag coefficients. This study is based on experimental measurements of the instantaneous 3D velocity and particle trajectory settling in water. A disk of D=30mm, t=1.5mm and ρ=1.38g/cm3 is manufactured as a reference particle. The disk was initially designed to lie within the Galileo number - dimensionless moment of inertia (G−I*) domain corresponding to the fluttering regime. A total of 35 other particles with the same frontal area and material properties were manufactured. These are manufactured to have different amplitudes (a) of the sinusoidal wave on the edge and number of cycles (N) around the entire perimeter. Thus, 5 sets of particles are manufactured with different relative wave amplitudes; i.e. a/D=0.03, 0.05, 0.1, 0.15, 0.2. Each set consisting of 7 particles from N=4 to N=10. The isoperimetric quotient is used as a measure of the particle circularity and is also linked with different characteristic settling behaviors. Disks and other planar particles with small a/D ratio were found to descent preferably with ‘Planar zig-zag’ behavior with events of high tilted angle. In contrast, particles with high a/D ratio were found to follow a more uniform descent with low tilted angle to the vertical motion. The differences in projected frontal area were shown not to be sufficient to compensate the differences in descent velocity, leading to unequal drag coefficients. Therefore, we believe that the falling styles of these irregular particles go hand by hand with characteristic wake structures, as shown for disks with various dimensionless moment of inertia, that enhance the descent of particles with low circularity.</p
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