Faraday waves, also known as Faraday ripples, named after

Michael Faraday Michael Faraday (; 22 September 1791 – 25 August 1867) was an English scientist who contributed to the study of electromagnetism and electrochemistry. His main discoveries include the principles underlying electromagnetic inducti ...

(1791–1867), are

nonlinear In mathematics and science, a nonlinear system is a system in which the change of the output is not proportional to the change of the input. Nonlinear problems are of interest to engineers, biologists, physicists, mathematicians, and many othe ...

standing waves that appear on liquids enclosed by a vibrating receptacle. When the vibration frequency exceeds a critical value, the flat hydrostatic surface becomes unstable. This is known as the Faraday

instability In numerous fields of study, the component of instability within a system is generally characterized by some of the outputs or internal states growing without bounds. Not all systems that are not stable are unstable; systems can also be mar ...

. Faraday first described them in an appendix to an article in the '' Philosophical Transactions'' of the

Royal Society of London The Royal Society, formally The Royal Society of London for Improving Natural Knowledge, is a learned society and the United Kingdom's national academy of sciences. The society fulfils a number of roles: promoting science and its benefits, re ...

in 1831. If a layer of liquid is placed on top of a vertically oscillating piston, a pattern of standing waves appears which oscillates at half the driving frequency, given certain criteria of

. This relates to the problem of parametric resonance. The waves can take the form of stripes, close-packed

hexagon In geometry, a hexagon (from Greek , , meaning "six", and , , meaning "corner, angle") is a six-sided polygon. The total of the internal angles of any simple (non-self-intersecting) hexagon is 720°. Regular hexagon A '' regular hexagon'' has ...

s, or even

squares In Euclidean geometry, a square is a regular quadrilateral, which means that it has four equal sides and four equal angles (90- degree angles, π/2 radian angles, or right angles). It can also be defined as a rectangle with two equal-length a ...

quasiperiodic Quasiperiodicity is the property of a system that displays irregular periodicity. Periodic behavior is defined as recurring at regular intervals, such as "every 24 hours". Quasiperiodic behavior is a pattern of recurrence with a component of unpred ...

patterns. Faraday waves are commonly observed as fine stripes on the surface of wine in a

wine glass A wine glass is a type of glass that is used to drink and taste wine. Most wine glasses are stemware (goblets), i.e., they are composed of three parts: the bowl, stem, and foot. Shapes The effect of glass shape on the taste of wine has not been ...

that is ringing like a bell. Faraday waves also explain the 'fountain' phenomenon on a

singing bowl A standing bell or resting bell is an inverted bell (instrument), bell, supported from below with the rim uppermost. Such bells are normally bowl-shaped, and exist in a wide range of sizes, from a few centimetres to a metre in diameter. They are ...

. The Faraday wave and its

wavelength In physics, the wavelength is the spatial period of a periodic wave—the distance over which the wave's shape repeats. It is the distance between consecutive corresponding points of the same phase on the wave, such as two adjacent crests, t ...

is analogous to the

de Broglie wave Matter waves are a central part of the theory of quantum mechanics, being an example of wave–particle duality. All matter exhibits wave-like behavior. For example, a beam of electrons can be diffracted just like a beam of light or a water wave ...

with the de Broglie wavelength in De Broglie–Bohm theory in the field of

quantum mechanics Quantum mechanics is a fundamental theory in physics that provides a description of the physical properties of nature at the scale of atoms and subatomic particles. It is the foundation of all quantum physics including quantum chemistr ...

Application

Assembly of microscale beads on Faraday waves

Faraday waves are used as a liquid-based template for directed assembly of microscale materials including soft matter,

rigid bodies In physics, a rigid body (also known as a rigid object) is a solid body in which deformation is zero or so small it can be neglected. The distance between any two given points on a rigid body remains constant in time regardless of external fo ...

, biological entities (''e.g.'', individual cells, cell spheroids and cell-seeded microcarrier beads).P. Chen, Z. Luo, S. Guven, S. Tasoglu, A. Weng, A. V. Ganesan, U. Demirci, Advanced Materials 2014, 10.1002/adma.201402079. http://onlinelibrary.wiley.com/doi/10.1002/adma.201402079/abstract Unlike solid-based template, this liquid-based template can be dynamically changed by tuning vibrational frequency and acceleration and generate diverse sets of symmetrical and periodic patterns. This phenomenon is also used by alligators to call mates. They vibrate their lungs at low frequencies slightly below the surface, causing their spikes to move and induce surface waves. These surface waves are basically Faraday waves and one can observe the splashing effect characteristic of certain resonances. This effect can also be used for mixing two liquids acoustically. Faraday waves form on the interface between the two liquids, which increases the surface area between the two, rapidly and thoroughly mixing the liquids.

References

External links

YouTube video of Faraday waves in corn starch.

YouTube video Yves Couder Explains Wave/Particle Duality via Silicon Droplets

YouTube video of Singing Bowl creating Fountain
{{Use dmy dates, date=May 2020 Wave mechanics Fluid dynamics Michael Faraday

Application

See also

References

External links