نتایج جستجو برای: shear turbulence
تعداد نتایج: 106498 فیلتر نتایج به سال:
We study large-scale dynamo action due to turbulence in the presence of a linear shear flow. Our treatment is quasilinear and equivalent to the standard "first-order smoothing approximation." However it is non perturbative in the shear strength. We first derive an integrodifferential equation for the evolution of the mean magnetic field, by systematic use of the shearing coordinate transformati...
s. We show that strong edge magnetic shear which is generic to divertor plasmas makes the shearing of turbulence eddys in toroidal geometry more effective. From calculations of the shearing rates for KSTAR edge parameters, we conclude that the enhanced magnetic shear at the diverted KSTAR plasma edge facilitates shear suppression of turbulence and ensuing H-mode transition.
The suppression of turbulence by mean flow shear is shown to apply to nonionized flows as well as plasmas. However, besides the criterion that the shearing rate exceed the turbulent decorrelation rate, there are three additional conditions. These stipulate that the shear flow must be stable, that turbulence must remain in the domain of flow shear for longer than an eddy turnover time, and that ...
A severe case of stenosis in coronary arteries results in turbulence in the blood flow which may lead to the formation or progression of atherosclerosis. This study investigated the turbulent blood flow in a coronary artery with rigid walls, as well as 80% single and double stenoses on blood flow. A finite element-based software package, ADINA 8.8, was employed to model the blood flow. The hemo...
This paper describes the physical mechanisms responsible for turbulence control and transport barrier formation on DIII–D as determined from a synthesis of results from different enhanced confinement regimes, including quantitative and qualitative comparisons to theory. A wide range of DIII–D data support the hypothesis that a single underlying physical mechanism, turbulence suppression via ExB...
Rotation and shear flows are ubiquitous features of many astrophysical and geophysical bodies. To understand the origin of large-scale shear flow and its effect on turbulent transport in these systems, we consider a forced turbulence and investigate the combined effect of rotation and shear flow on the turbulence properties. Specifically, we study how rotation and flow shear influence the gener...
Direct numerical simulation of uniform shear flow is used to study the anisotropy of fluctuating motion in a stably stratified medium with uniform mean shear. Turbulence is found to be three dimensional over a wjde range of gradient Richardson numbers in the two Bows investigated here: vertical mean shear ($$-) and horizontal mean shear (g). The role of the turbulent F’roude number in establish...
The aim of the current work is to investigate a series of new subgrid models by employing the Kolmogorov equation of ltered quantities (KEF), which is an exact relation of turbulence in physical space. Di erent formulations of KEF are derived, including the forms in velocity eld (homogeneous isotropic turbulence, inhomogeneous anisotropic turbulence, homogeneous shear turbulence, homogeneous ro...
A WKB method was recently used to extend rapid distortion theory (RDT) to initially inhomogeneous turbulence strained by irrotational mean flows [S.V. Nazarenko, N. Kevlahan, B. Dubrulle, J. Fluid Mech. 390 (1999) 325]. This theory takes into account the feedback of turbulence on the mean flow, and it was used by Nazarenko et al. to explain the effect of strain reduction caused by turbulence ob...
The mechanism of internal transport barrier (ITB) collapse in the reversed magnetic shear configuration is investigated using a global Ion Temperature Gradient driven drift wave (ITG) turbulence code. The heating source and the Toroidal Momentum Source (TMS) is introduced to follow the selfconsistent evolution of the ion temperature and flow profiles. The Toroidal Flow Shear (TFS) effect on the...
نمودار تعداد نتایج جستجو در هر سال
با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید