1,188 research outputs found
Estudio de la remisión legal de la deuda en sede concursal
La remisión legal de la deuda es el elemento clave del concurso de persona física. La
remisión es una modalidad de resolución contractual por dificultad subjetiva en el
cumplimiento. Cumplidos los requisitos legalmente previstos para que opere la
remisión, la resolución judicial que la declara determina la extinción de las deudas del
concursado. Los beneficiarios de esta institución son las personas físicas empresarias y,
con menor alcance, a otras personas físicas
Thermal and electrohydrodynamic plumes: a compartive study
This paper deals with self similar thermal and electrohydrodynamic (EHD) plumes. The former
arises from hot lines or points, whereas the latter arises when sharp metallic contours submerged in
non conducting liquids support high electrostatic potential, resulting in charge injection. Although
the motive force is buoyancy in one case and Coulomb force in the other, it is shown that the
solution for EHD plumes is the same as for thermal plumes in the limit of large Prandtl numbers.
We present the analysis of axisymmetric plumes for large values of Prandtl number, and this analysis
is subsequently applied to EHD plumes. The validity of the approximations for EHD plumes is
discussed in the light of experimental data.Ministerio de ciencia y tecnología PB93-118
On two-dimensional finite amplitude electro-convection in a dielectric liquid induced by a strong unipolar injection
The hydrodynamic stability of a dielectric liquid subjected to strong unipolar injection is numerically investigated. We determined the linear criterion Tc (T being the electric Rayleigh number) and finite amplitude one Tf over a wide range of the mobility parameter M. A noticeable discrepancy is shown for Tf between our numerical prediction and the value predicted by stability analysis, which is due to the velocity field used in stability analysis. Recent studies revealed a transition of the flow structure from one cell to two with an increase in T. We demonstrate that this transition results in a new subcritical bifurcationMinisterio de Ciencia y Tecnología FIS2011-25161Junta de Andalucía P10-FQM-5735Junta de Andalucía P09-FQM-458
Electroconvection in a dielectric liquid between two concentric half-cylinders with rigid walls: Linear and nonlinear analysis
We study the linear stability and nonlinear behavior of the electroconvection between two concentric halfcylinders
with no-slip conditions on all boundaries. The no-slip condition makes impossible to apply the standard
modal approach. Hence, we apply a finite element technique similar to the one we have used in a previous
paper about the electroconvection in a rectangular enclosed domain. When compared to the classical problem of
electroconvection between two full concentric cylinders, the linear criterion is higher, due to the viscous shear
introduced by the lateral walls. As a consequence, the structure of the eigenmodes is very different. There is a
repulsion between modeswith the same symmetry, forcing pairs of modes to cross each other repeatedly. For inner
injection and small value of the ratio between the inner and outer radii the no-slip condition changes the nature
of the bifurcation from subcritical to supercritical, while it is always subcritical for outer injection. To understand
this behavior, we perform a modal analysis using the eigenfunctions obtained from the linear stability analysis
as modal basis. We show that the supercritical branch is originated by the nonorthogonality of the modes when
no-slip boundary conditions are imposed. These mechanism explains the previously unexplained appearance of
the supercritical branch in the enclosed rectangular configuration.Ministerio de Economía y Competitividad FIS2014-54539-
Complex flow patterns at the onset of annular electroconvection in a dielectric liquid subjected to an arbitrary unipolar injection
We numerically investigated the annular electroconvection that takes place in a dielectric liquid lying between two concentric cylinder electrodes. A uniform injection of arbitrary strengths either from the inner or outer cylinder introduces free charge carriers into the system, and the resulting Coulomb force induces electroconvection. The problem is characterized by a linear instability that corresponds to the onset of flow motion. The linear stability criteria were determined from direct numerical results and by linear stability analysis, and the results obtained with the two approaches show an excellent agreement. We focused on the fully developed flow pattern in the finite amplitude regime. We observed very different flow motions that were highly dependent on the injection strength.Ministerio de Ciencia y Tecnología FIS2011-25161Junta de Andalucía P10-FQM-5735Junta de Andalucía P09-FQM-458
Submarine emissions on the seafloor: from cold sepes to hot vents
The main types of submarine geological emissions are classified as cold seeps (hydrocarbons and brines)
and hot vents. These processes result in the emission of geological fluids: brine, gases (mainly hydrocarbons), sediments and rocks. Submarine emissions are associated with an intensive geological, geochemical, thermal and biological activity (Judd and Hovland, 2007), and constitute a key process in the
dynamics of the global cycles of the planet Earth. These systems play a major role in the exchange of
matter and energy between the Geosphere and Hydrosphere, contributing to the greenhouse gases and
affecting the ocean chemistry (Dimitrov, 2002; Alt, 2003). They also control the evolution of continental
margins and oceanic basins (Paull y Dillon, 2001), and can produce the formation of significant and
strategic mineralizations, as well as focus the development of specific habitats (Boetius et al., 2000) and
provide an insight of deeper parts of the crust.LIFE+ INDEMARES/CHICA (LIFE07/NAT/E/000732), CADHYS (P08-RNM-03581), MONTERA (CTM2009-14157-C02), VULCANO (CTM2012-36317) and SUBVENT (CGL2012-39524-C02)
Onset of convection in a finite two-dimensional container due to unipolar injection of ions
This work addresses the stability of a two-dimensional plane layer of a dielectric liquid enclosed in wall
bounded cavities of different aspect ratios and subjected to unipolar injection of ions. Numerical simulations
have been conducted to investigate the effect of lateralwalls, especially in the development of the electroconvective
instability. It is found that an unexpected change of the bifurcation nature occurs for certain cavity aspect ratios.
We showthat above the linear stability threshold for the rest state a supercritical bifurcation arises. This bifurcation
takes place at a given value Tc1 of the parameter T (the electric Rayleigh number). Then, a second subcritical
bifurcation occurs at a second threshold Tc2, featuring a typical hysteresis loop with an associated nonlinear
criterion Tf , which is very characteristic of the Coulomb-driven convection. This behavior has been confirmed
by different numerical codes based on different numerical methods. The physical mechanism which leads to this
situation is analyzed and discussed. The evolution of the bifurcation diagrams with the aspect ratio of the cavity
is also provided and analyzed.Ministerio de ciencia y tecnología FIS2011-25161Junta de Andalucía P10-FQM-5735Junta de Andalucía P09-FQM-458
Electrohydrodynamic linear stability analysis of dielectric liquids subjected to unipolar injection in a rectangular enclosure with rigid sidewalls
We investigate the linear stability threshold of a dielectric liquid subjected to unipolar
injection in a 2D rectangular enclosure with rigid boundaries. A finite element formulation
transforms the set of linear partial differential equations that governs the system into a set
of algebraic equations. The resulting system poses an eigenvalue problem. We calculate
the linear stability threshold, as well as the velocity field and charge density distribution,
as a function of the aspect ratio of the domain. The stability parameter as a function
of the aspect ratio describes paths of symmetry-breaking bifurcation. The symmetry
properties of the different linear modes determine whether these paths cross each other
or not. The resulting structure has important consequences in the non-linear behavior of
the system after the bifurcation points.Ministerio de ciencia y tecnología FIS2011-25161Junta de Andalucía P10-FQM-5735Junta de Andalucía P09-FQM-458
Finite amplitude electroconvection induced by strong unipolar injection between two coaxial cylinders
We perform a theoretical and numerical study of the Coulomb-driven electroconvection flow of a dielectric liquid between two coaxial cylinders. The specific case where the inner to outer diameter ratio is 0.5 is analyzed. A strong unipolar injection of ions either from the inner or outer cylinder is considered to introduce free charger carriers into the system. A finite volume method is used to solve all governing equations including Navier-Stokes equations and a simplified set of Maxwell’s equations. The flow is characterized by a subcritical bifurcation in the finite amplitude regime. A linear stability criterion and a nonlinear one that correspond to the onset and stop of the flow motion, respectively, are linked with a hysteresis loop. In addition, we also explore the behavior of the system for higher values of the stability parameter. For inner injection, we observe a transition between the patterns made of 7 and 8 pairs of cells, before an oscillatory regime is attained. Such a transition leads to a second finite amplitude stability criterion. A simple modal analysis reveals that the competition of different modes is at the origin of this behavior. The charge density as well as velocity field distributions are provided to help understanding the bifurcation behavior.Ministerio de ciencia y tecnología FIS2011-25161Junta de Andalucía P10-FQM-5735Junta de Andalucía P09-FQM-458
Dynamics of EHD Laminar Plumes: scaling analysis and integral model
In this paper electrohydrodynamic (EHD) plumes are examined in the region far from the injecting
electrode and the collector plate, for both two-dimensional and axisymmetric geometries. The
relative importance of the conduction mechanisms (convection, drift and diffusion of electric charge)
is analyzed. Diffusion turns out to be negligible compared to convection and drift for the experimental
conditions. But the transverse drift (Coulomb repulsion) is of the same order of magnitude
than convection. We find a set of three differential equations giving the evolution of the velocity at
the center of the plume and the widths of the plume and the charged core inside.Ministerio de Ciencia y Tecnología PB96-137
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