Search results for "Outflow"

Inflow/outflow pressure boundary conditions for smoothed particle hydrodynamics simulations of incompressible flows

2017

Abstract Open Boundary treatment is a well-known issue in the Smoothed Particle Hydrodynamics (SPH) method, mainly when the truly Incompressible (ISPH) approach is employed. In the paper a novel method is proposed to set pressure boundary conditions in the computational domain inlets and outlets, without requiring the velocity profile assignment. The new technique allows to treat in the same way inflow and outflow sections, effectively dealing with the release of new particles at inlets and the deactivation of the ones leaving the domain through the outlets. Several 3D numerical tests, both in the laminar and turbulent regimes, are carried out to validate the proposed numerical scheme consi…

Transcatheter radiofrequency perforation and stent implantation for palliation of pulmonary atresia in a 3060-g infant

1995

In a 3060-g infant with fibromuscular pulmonary atresia an open right ventricular outflow tract was created by means of interventional cardiological methods. Following two inadvertent perforations without sequelae or clinical symptoms, radiofrequency perforation and subsequent balloon dilatation were successfully performed. The implantation of a Palmaz iliac stent led to a predictable communication between the right ventricle and pulmonary artery.

Numerical simulation of transcatheter mitral valve replacement: The dynamic implication of LVOT obstruction in the valve-in-ring case.

2022

Transcatheter mitral valve replacement (TMVR) has been used for “off-label” treatment when annuloplasty band ring for mitral repair fails. However, the complex anatomy and function of the mitral valve may lead to fatal complications as a result of the left ventricular outflow tract (LVOT) obstruction in TMVR. We report the structural and hemodynamic response of LVOT obstruction resulting from TMVR with the Edwards SAPIEN 3 Ultra (S3) device. We modified the original Living Heart Human Model (LHHM) to account for a failed mitral valve with an annuloplasty band ring and simulated the cardiac beating condition in the setting of S3 device implantation. Findings demonstrated a high dynamic behav…

The jets and disc of SS 433 at super-Eddington luminosities

2009

We examine the jets and the disc of SS 433 at super-Eddington luminosities with 600 times Eddington critical accretion rate by time-dependent two-dimensional radiation hydrodynamical calculations, assuming alpha-model for the viscosity. One-dimensional supercritical accretion disc models with mass loss or advection are used as the initial configurations of the disc. As a result, from the initial advective disc models with alpha =0.001 and 0.1, we obtain the total luminosities 2.5x10^{40} and 2.0x10^{40} erg/s. The total mass-outflow rates are 4x10^{-5} and 10^{-4} solar-mass/yr and the rates of the relativistic axial outflows in a small half opening angle of 1 degree are about 10^{-6} solar…

Testing the Outflow Process over a Triangular Labyrinth Weir

2017

In this paper, the dimensionless stage-discharge relation for a sharp-crested triangular labyrinth weir, determined in a previous study, is initially tested by some experimental runs carried out in a laboratory flume. According to this relationship, the flow magnification is affected by the length-magnification ratio and the head to one cycle width ratio. The measurements allowed to test the applicability of this dimensionless relation for different values of both the angle of the sidewall to the main flow direction and the weir height. Finally, the proposed dimensionless equation was also tested by using experimental measurements carried out for broad-crested triangular labyrinth weir.

X-ray Emission Mechanisms in Herbig - Haro objects .

2006

Spurectomy: A novel modification of non-penetrating deep sclerectomy.

2020

To evaluate the outcomes of a novel modification of the non-penetrating deep sclerectomy (NPDS) approach for glaucoma management called spurectomy.Observational comparative non-randomized retrospective study including 98 glaucomatous eyes of 76 patients operated on with the spurectomy technique consisting of the combination of the excision of the scleral spur with NPDS (groupA). A control group (groupB) including 53 glaucomatous eyes of 43 patients operated on with classical NPDS was also included. Changes in intraocular pressure (IOP) and medications required as well as complications were recorded in a 12-month follow-up.Mean IOP decreased from 25.69±8.11 preoperatively to 15.73±4.16mm Hg …

The Highly Collimated Radio Jet of HH 80–81: Structure and Nonthermal Emission

2017

Radio emission from protostellar jets is usually dominated by free-free emission from thermal electrons. However, in some cases, it has been proposed that non-thermal emission could also be present. This additional contribution from non-thermal emission has been inferred through negative spectral indices at centimeter wavelengths in some regions of the radio jets. In the case of HH 80-81, one of the most powerful protostellar jets known, linearly polarized emission has also been detected, revealing that the non-thermal emission is of synchrotron nature from a population of relativistic particles in the jet. This result implies that an acceleration mechanism should be taking place in some pa…

Unemployment Flows in Finland, 1969-95: A Time Series Analysis

1998

We adopt a flow approach to analyse Finnish unemployment experience during the last three decades. In addition to data on short-term and total outflow and inflow rates from a relatively long period beginning in 1969, we also have data on duration-specific outflow rates for the period 1984 I–96 II which encompasses the spectacular increase in unemployment in the early nineties. The empirical study shows that both the inflow and the outflow is mainly driven by variation in job opportunities. For a given vacancy-unemployment ratio, the outflow rate has fallen because of changes in unemployment compensation, demographic structure and emigration. The outflow has been only marginally affected by …

Instability of relativistic sheared jets and distinction between FRI and FRII sources

2002

We investigate the shear-driven instability of nonmagnetic relativistic jets with the bulk velocity, V , dependent on the cylindric radius, r. It is shown that instability can arise for any dependence of the velocity (or the Lorentz factor that is the same) on r. The shear-driven instability can e ectively operate in the whole volume of a jet. The growth time can be shorter than that of the Kelvin-Helmholtz instability. The considered instability leads to a turbulization of jets and can account for a distiction between the jets in the FRI and FRII sources. Urpin, V., Vadim.Urpin@uv.es