Turbulence

In fluid dynamics, turbulence or turbulent flow is a flow regime characterized by chaotic property changes. This includes low momentum diffusion, high momentum convection, and rapid variation of pressure and flow velocity in space and time.

Flow in which the kinetic energy dies out due to the action of fluid molecular viscosity is called laminar flow. While there is no theorem relating the non-dimensional Reynolds number (Re) to turbulence, flows at Reynolds numbers larger than 5000 are typically (but not necessarily) turbulent, while those at low Reynolds numbers usually remain laminar. In Poiseuille flow, for example, turbulence can first be sustained if the Reynolds number is larger than a critical value of about 2040; moreover, the turbulence is generally interspersed with laminar flow until a larger Reynolds number of about 4000.

In turbulent flow, unsteady vortices appear on many scales and interact with each other. Drag due to boundary layer skin friction increases. The structure and location of boundary layer separation often changes, sometimes resulting in a reduction of overall drag. Although laminar-turbulent transition is not governed by Reynolds number, the same transition occurs if the size of the object is gradually increased, or the viscosity of the fluid is decreased, or if the density of the fluid is increased. Nobel Laureate Richard Feynman described turbulence as "the most important unsolved problem of classical physics."

Turbulence (2011 film)

Turbulence is a 2011 British film directed by Michael B. Clifford.

It tells the story of a struggling pub and a local rock band. The film was shot in the Kings Heath area of Birmingham.

External links

Turbulence (NSA)

Turbulence is a United States National Security Agency (NSA) information-technology project started c. 2005. It was developed in small, inexpensive "test" pieces rather than one grand plan like its failed predecessor, the Trailblazer Project. It also includes offensive cyberwarfare capabilities, like injecting malware into remote computers. The U.S. Congress criticized the project in 2007 for having similar bureaucratic problems as the Trailblazer Project.

Criticism

According to Siobhan Gorman in a 2007 Baltimore Sun article, "The conclusion in Congress, two former government officials said, was that Turbulence was over budget, not delivering and poorly led, and that there was little or no strategy to pull it all together."

Link to Trailblazer

Trailblazer, the predecessor of Turbulence, had been cancelled in 2006 after a congressional investigation and a Defense Department's Inspector General's report found it over budget, wasteful, and ineffective.

One of the Trailblazer whistleblowers who helped with the inspector-general report, Thomas Andrews Drake, was later charged under the Espionage Act of 1917 for allegedly retaining five documents in his home. Two of those documents were about Turbulence; his defense pointed out that one of these documents was clearly marked "UNCLASSIFIED" and the other was declassified shortly after his indictment. Thomas Drake pleaded guilty to a misdemeanor count of unauthorized use of a computer on June 10, 2011, and was sentenced to one year probation.

Epsilon

Epsilon (uppercase Ε, lowercase ε or lunate ϵ; Greek: Έψιλον) is the fifth letter of the Greek alphabet, corresponding phonetically to a close-mid front unrounded vowel /e/. In the system of Greek numerals it has the value five. It was derived from the Phoenician letter He . Letters that arose from epsilon include the Roman E, Ë and Ɛ, and Cyrillic Е, È, Ё, Є and Э.

The name of the letter was originally εἶ (Ancient Greek: [êː]), but the name was changed to ἒ ψιλόν (e psilon "simple e") in the Middle Ages to distinguish the letter from the digraph αι, a former diphthong that had come to be pronounced the same as epsilon.

In essence, the uppercase form of epsilon looks identical to Latin E. The lowercase version has two typographical variants, both inherited from medieval Greek handwriting. One, the most common in modern typography and inherited from medieval minuscule, looks like a reversed "3". The other, also known as lunate or uncial epsilon and inherited from earlier uncial writing, looks like a semicircle crossed by a horizontal bar. While in normal typography these are just alternative font variants, they may have different meanings as mathematical symbols. Computer systems therefore offer distinct encodings for them. In Unicode, the character U+03F5 "Greek lunate epsilon symbol" (ϵ) is provided specifically for the lunate form. In TeX, \epsilon () denotes the lunate form, while \varepsilon () denotes the inverted-3 form.

Epsilon (rocket)

The Epsilon rocket (イプシロンロケット, Ipushiron roketto) (formerly Advanced Solid Rocket) is a Japanese solid-fuel rocket designed to launch scientific satellites. It is a follow-on project to the larger and more expensive M-V rocket which was retired in 2006. The Japan Aerospace Exploration Agency (JAXA) began developing the Epsilon in 2007. It is designed to be capable of placing a 1.2 tonne payload into low Earth orbit.

Vehicle description

The development aim is to reduce costs compared to the US$70 million launch cost of an M-V. The Epsilon costs US$38 million (£23m) per launch, which is half the cost of its predecessor. Development expenditures by JAXA exceeded US$200 million.

To reduce the cost per launch the Epsilon uses the existing SRB-A3 as a solid rocket booster on the H-IIA rocket as its first stage. Existing M-V upper stages will be used for the second and third stages, with an optional fourth stage available for launches to higher orbits. The J-1 rocket, which was developed during the 1990s, but abandoned after just one launch, used a similar design concept, with an H-II booster and Mu-3S-II upper stages.

Epsilon (Dreamtale album)

Epsilon is the fifth studio album by Finnish power metal band Dreamtale. Released on The Secret Door record label on 11 May 2011 in Finland, with an earlier 20 April 2011 release in Japan, it reached number 39 on Suomen virallinen lista, The Official Finnish Charts.

Track listing

Personnel