The chaotic flow of water cascading down a mountainside is known as turbulence. It is complex, irregular and unpredictable, but we should count our blessings that it exists. Without turbulence, we would gasp for breath, struggling to absorb oxygen or be asphyxiated by the noxious fumes belching from motorcars, since pollutants would not be dispersed through the atmosphere [TM101, or search for “thatsmaths” at irishtimes.com].

## Posts Tagged 'Fluid Dynamics'

### Thank Heaven for Turbulence

Published October 20, 2016 Irish Times Leave a CommentTags: Applied Maths, Fluid Dynamics

### Modelling Rogue Waves

Published May 5, 2016 Irish Times Leave a CommentTags: Applied Maths, Fluid Dynamics, Wave Motion

There are many eyewitness accounts by mariners of gigantic waves – almost vertical walls of water towering over ocean-going ships – that appear from nowhere and do great damage, sometimes destroying large vessels completely. Oceanographers, who have had no way of explaining these ‘rogue waves’, have in the past been dismissive of these reports [TM090, or search for “thatsmaths” at irishtimes.com].

### Richardson’s Fantastic Forecast Factory

Published January 7, 2016 Irish Times Leave a CommentTags: Applied Maths, Computer Science, Fluid Dynamics

Modern weather forecasts are made by calculating solutions of the mathematical equations that express the fundamental physical principles governing the atmosphere [TM083, or search for “thatsmaths” at irishtimes.com]

The solutions are generated by complex simulation models with millions of lines of code, implemented on powerful computer equipment. The meteorologist uses the computer predictions to produce localised forecasts and guidance for specialised applications.

### The Flight of a Golf Ball

Published December 3, 2015 Irish Times Leave a CommentTags: Applied Maths, Fluid Dynamics

Golf balls fly further today, thanks to new materials and mathematical design. They are a triumph of chemical engineering and aerodynamics. They are also big business, and close to a billion balls are sold every year. [TM081: search for “thatsmaths” at Irish Times ].

### Life’s a Drag Crisis

Published November 26, 2015 Occasional Leave a CommentTags: Fluid Dynamics, History

The character of fluid flow depends on a dimensionless quantity, the Reynolds number. Named for Belfast-born scientist Osborne Reynolds, it determines whether the flow is laminar (smooth) or turbulent (rough). Normally the drag force increases with speed.

The Reynolds number is defined as Re = *VL*/*ν* where *V* is the flow speed, *L* the length scale and *ν* the viscosity coefficient. The transition from laminar to turbulent flow occurs at a critical value of Re which depends on details of the system, such as surface roughness.

### The Hodograph

Published April 9, 2015 Occasional Leave a CommentTags: Astronomy, Fluid Dynamics, Geophysics

The Hodograph is a vector diagram showing how velocity changes with position or time. It was made popular by William Rowan Hamilton who, in 1847, gave an account of it in the Proceedings of the Royal Irish Academy. Hodographs are valuable in fluid dynamics, astronomy and meteorology.

### Plateau’s Problem and Double Bubbles

Published January 22, 2015 Occasional Leave a CommentTags: Algorithms, Fluid Dynamics, Physics, Topology

Bubbles floating in the air strive to achieve a spherical form. Large bubbles may oscillate widely about this ideal whereas small bubbles quickly achieve their equilibrium shape. The sphere is optimal: it encloses maximum volume for any surface of a given area. This was stated by Archimedes, but he did not have the mathematical techniques required to prove it. It was only in the late 1800s that a formal proof of optimality was completed by Hermann Schwarz [Schwarz, 1884].