Keywords magnetohydrodynamics (MHD) –turbulence –Sun: activity –Sun: magnetic fields We introduce on/offintermittencyinto amean field dynamo model by imposing stochastic fluctuations in either the alpha effect or through theinclusion of afluctuatingelectromotivef orce. Sufficiently strong smallscalefluctuations with time scales of theorder of 0.3–3 years can produce long term variations in thes...

Key words galaxies: magnetic fields – magnetohydrodynamics (MHD) – turbulence We summarize the current state of the long term discussion about the saturation mechanisms associated with rapid growth of small-scale magnetic field, that operate in large-scale galactic dynamos, and related problems with magnetic helicity conservation. Our general conclusion is that, taking into account magnetic hel...

This paper describes an artwork created in response to a question about the role of the artist in communicating climate change issues. The artwork, titled Turbulent World, incorporates turbulence and surprise as a means to visualize the potential instability of our culture and the environment due to climatic changes indicated by increased worldwide temperatures. The artwork makes use of a custo...

The unique atmospheric conditions present at sites such as Dome C on the Antarctic plateau are very favorable for high spatial resolution astronomy. At Dome C, the majority of the optical turbulence is confined to a 30 to 40 m thick stable boundary layer that results from the strong temperature inversion created by the heat exchange between the air and the ice-covered ground. To fully realize t...

In addition to low-level windshear (below 1600 feet), low-level turbulence could also adversely affect arriving/departing aircraft at the airport. Turbulent airflow may occur in clear-air/non-rainy weather conditions, e.g. terrain effect at the Hong Kong International Airport (HKIA) or building’s disruptions at Haneda Airport (Tokyo International Airport) in Japan. Such airflow disturbances cou...

With the increasing role of high performance computing in attacking complex physical problems, there is an urgent need for the development of advanced computational technology to provide scientists with high-level assistance in the analysis, interpretation, and modeling of a massive amount of quantitative data. A critical area where this need is quite evident is the problem of turbulence . The ...

Observations are presented to show that in an adverse pressure gradient boundary layer, beneath free-stream turbulence, the interaction between Klebanoff streaks and naturally arising instability waves leads to helical disturbances which break down to form turbulent spots. This occurs under low to moderate levels, 1%–2%, of free-stream turbulence. At high levels of free-stream turbulence, conve...

In the so-called ‘alpha-heating’ experiment performed on the JET tokamak during the deuterium–tritium campaign of 1997, the ion temperature was found to be far exceeding (both in absolute value and in its rise time) the level that could have been expected from direct collisional heating by the fusion-born alpha particles themselves and energy equipartition with the electrons. To date, no explan...

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...

Airborne encounters with clear air turbulence (CAT) continue to significantly affect the safety and efficiency of commercial aviation. Fatalities, injuries and the additional costs associated with both encountering and avoiding turbulence are serious problems. Turbulence-induced injuries are airlines’ most frequent source of insurance and workers’ compensation claims. This paper will discuss th...