نتایج جستجو برای: vorticity

تعداد نتایج: 6206  

Journal: :American journal of physiology. Heart and circulatory physiology 2015
Brett E Fenster James Browning Joyce D Schroeder Michal Schafer Chris A Podgorski Jamie Smyser Lori J Silveira J Kern Buckner Jean R Hertzberg

Right ventricular diastolic dysfunction (RVDD) is an important prognostic indicator in pulmonary arterial hypertension (PAH). RV vortex rings have been observed in healthy subjects, but their significance in RVDD is unknown. Vorticity, the local spinning motion of an element of fluid, may be a sensitive measure of RV vortex dynamics. Using four-dimensional (4D) flow cardiac magnetic resonance i...

2006
BRIAN J. GAUDET WILLIAM R. COTTON MICHAEL T. MONTGOMERY

An idealized supercell simulation using the Regional Atmospheric Modeling System (RAMS) produced an elongated low-level mesocyclone that subsequently collapsed into a concentrated vortex. Though vorticity continually increased in the mesocyclone due to horizontal convergence, the collapse phase was additionally characterized by rapidly decreasing pressure, closed streamlines, and the creation o...

2005
Kamran Mohseni Ali Shakouri Rajeev J. Ram Mathew C. Abraham

The hydrodynamic model of electron transport in semiconductors is analyzed and, in analogy with vortices in fluid mechanics, the curl of electron velocity is defined as electron vorticity, and the transport equation for the electron vorticity is derived. Aside from the classical hydrodynamic sources of vorticity, collision terms in the continuity and momentum equations are identified as sources...

2004
JAMES C. McWILLIAMS

A study is made of some numerical calculations of two-dimensional and geostrophic turbulent flows. The primary result is that, under a broad range of circumstances, the flow structure has its vorticity concentrated in a small fraction of the spatial domain, and these concentrations typically have lifetimes long compared with the characteristic time for nonlinear interactions in turbulent flow (...

2012
Paschalis Karageorgis PASCHALIS KARAGEORGIS

We derive the dispersion relation for linearized small-amplitude gravity waves for various choices of non-constant vorticity. To the best of our knowledge, this relation is only known explicitly in the case of constant vorticity. We provide a wide range of examples including polynomial, exponential, trigonometric and hyperbolic vorticity functions.

2006
Odd Erik Gundersen Samuel Rødal Geir Storli

We have reached our goal of implementing a computationally cheap algorithm for realtime rendering of realistic two-dimensional fire. The fire is simulated using computational fluid dynamics, vorticity confinement, and combustion modelling and visualized using black-body radiation. Small rotationally homogenous fires like torches and candles viewed in front are the best candidates when using thi...

2009
MATTHEW R. TURNER ANDREW P. BASSOM ANDREW D. GILBERT

The spreading and diffusion of two-dimensional vortices subject to weak external random strain fields is examined. The response to such a field of given angular frequency depends on the profile of the vortex and can be calculated numerically. An effective diffusivity can be determined as a function of radius and may be used to evolve the profile over a long time scale, using a diffusion equatio...

2004
Tsutomu Kambe

One of the important properties of boundary layer is, from the point of view of Strömungslehre, that it pumps vorticity into the flow field. Vorticity in fluid flows plays diverse roles and produces tremendous variety of flow phenomena. We consider four aspects of vorticity in fluid flows: (A) Kinematical aspect of a vortex sheet, (B) mechanical aspect of hydrodynamic impulse of a vortex system...

2015
ANNA BOHUN GIANLUCA CRIPPA

We consider solutions to the two-dimensional incompressible Euler system with only integrable vorticity, thus with possibly locally infinite energy. With such regularity, we use the recently developed theory of Lagrangian flows associated to vector fields with gradient given by a singular integral in order to define Lagrangian solutions, for which the vorticity is transported by the flow. We pr...

2010
P. F. CHOBOTER

Abyssal Abyssal flows, flows, as as part part of of the the global global thermohaline thermohaline circulation, circulation, make make a a sig­ sig­ nificant nificant contribution contribution to to the the flux flux of of heat heat over over the the earth, earth, and and therefore therefore affect affect the the planet's planet's climate. climate. In In the the Atlantic, Atlantic, the the dee...

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