Swash, or forewash in geography, is a turbulent layer of water that washes up on the beach after an incoming wave has broken. The swash action can move beach materials up and down the beach, which results in the cross-shore sediment exchange. The time-scale of swash motion varies from seconds to minutes depending on the type of beach (see Figure 1 for beach types). Greater swash generally occurs on flatter beaches. The swash motion plays the primary role in the formation of morphological features and their changes in the swash zone. The swash action also plays an important role as one of the instantaneous processes in wider coastal morphodynamics.
There are two approaches that describe swash motions: (1) swash resulting from the collapse of high-frequency bores (f>0.05 Hz) on the beachface; and (2) swash characterised by standing, low-frequency (f<0.05 Hz) motions. Which type of swash motion prevails is dependent on the wave conditions and the beach morphology and this can be predicted by calculating the surf similarity parameter εb (Guza & Inman 1975):
Where Hb is the breaker height, g is gravity, T is the incident-wave period and tan β is the beach gradient. Values εb>20 indicate dissipative conditions where swash is characterised by standing long-wave motion. Values εb<2.5 indicate reflective conditions where swash is dominated by wave bores.
Swash consists of two phases: uprush (onshore flow) and backwash (offshore flow). Generally uprush velocities are greater but of shorter duration compared to the backwash. Onshore velocities are at greatest at the start of the uprush and then decrease, whereas offshore velocities increase towards the end of the backwash. The direction of the uprush varies with the prevailing wind, whereas the backwash is always perpendicular to the coastline. This asymmetrical motion of swash can cause longshore drift as well as cross-shore sediment transport.
The swash zone is the upper part of the beach between backbeach and surf zone, where intense erosion occurs during storms (Figure 2). The swash zone is alternately wet and dry. Infiltration (hydrology) (above the water table) and exfiltration (below the water table) take place between the swash flow and the beach groundwater table. Beachface, berm, beach step and beach cusps are the typical morphological features associated with swash motion. Infiltration (hydrology) and sediment transport by swash motion are important factors that govern the gradient of the beachface.
The beachface is the planar, relatively steep section of the beach profile that is subject to swash processes (Figure 2). The beachface extends from the berm to the low tide level. The beachface is in dynamic equilibrium with swash action when the amount of sediment transport by uprush and backwash are equal. If the beachface is flatter than the equilibrium gradient, more sediment is transported by the uprush to result in net onshore sediment transport. If the beachface is steeper than the equilibrium gradient, the sediment transport is dominated by the backwash and this results in net offshore sediment transport. The equilibrium beachface gradient is governed by a complex interrelationship of factors such as the sediment size, permeability, and fall velocity in the swash zone as well as the wave height and the wave period. The beachface cannot be considered in isolation from the surf zone to understand the morphological changes and equilibriums as they are strongly affected by the surf zone and shoaling wave processes as well as the swash zone processes.
The berm is the relatively planar part of the swash zone where the accumulation of sediment occurs at the landward farthest of swash motion (Figure 2). The berm protects the backbeach and coastal dunes from waves but erosion can occur under high energy conditions such as storms. The berm is more easily defined on gravel beaches and there can be multiple berms at different elevations. On sandy beaches in contrast, the gradient of backbeach, berm and beachface can be similar. The height of the berm is governed by the maximum elevation of sediment transport during the uprush. The berm height can be predicted using the equation by Takeda and Sunamura (1982)
where Hb is the breaker height, g is gravity and T is the wave period.
The beach step is a submerged scarp at the base of the beachface (Figure 2). The beach steps generally comprise the coarsest material and the height can vary from several centimetres to over a metre. Beach steps form where the backwash interacts with the oncoming incident wave and generate vortex. Hughes and Cowell (1987) proposed the equation to predict the step height Zstep
where 'ws' is the sediment fall velocity. Step height increases with increasing wave (breaker) height (Hb), wave period (T) and sediment size.
The beach cusp is a crescent-shaped accumulation of sand or gravel surrounding a semicircular depression on a beach. They are formed by swash action and more common on gravel beaches than sand. The spacing of the cusps is related to the horizontal extent of the swash motion and can range from 10 cm to 50 m. Coarser sediments are found on the steep-gradient, seaward pointing ‘cusp horns’ (Figure 3). Currently there are two theories that provide an adequate explanation for the formation of the rhythmic beach cusps: standing edge waves and self-organization.
The standing edge wave theory, which was introduced by Guza and Inman (1975), suggests that swash is superimposed upon the motion of standing edge waves that travel alongshore. This produces a variation in swash height along the shore and consequently results in regular patterns of erosion. The cusp embayments form at the eroding points and cusp horns occur at the edge wave nodes. The beach cusp spacing can be predicted using the sub-harmonic edge wave model
where T is incident wave period and tanβ is beach gradient.
This model only explains the initial formation of the cusps but not the continuing growth of the cusps. The amplitude of the edge wave reduces as the cusps grow, hence it is a self-limiting process.
The self-organization theory was introduced by Werner and Fink (1993) and it suggests that beach cusps form due to a combination of positive feedback that is operated by beach morphology and swash motion encouraging the topographic irregularity and negative feedback that discourages accretion or erosion on well-developed beach cusps. It is relatively recent that the computational resources and sediment transport formulations became available to show that the stable and rhythmic morphological features can be produced by such feedback systems. The beach cusp spacing, based on the self-organization model, is proportional to the horizontal extent of the swash motion S using the equation
where the constant of proportionality f is c. 1.5.
The cross-shore sediment exchange, between the subaerial and sub-aqueous zones of the beach, is primarily provided by the swash motion. The transport rates in the swash zone are much higher compared to the surf zone and suspended sediment concentrations can exceed 100 kg/m3 close to the bed. The onshore and offshore sediment transport by swash thus plays a significant role in accretion and erosion of the beach.
There are fundamental differences in sediment transport between the uprush and backwash of the swash flow. The uprush, which is mainly dominated by bore turbulence, especially on steep beaches, generally suspend sediments to transport. Flow velocities, suspended sediment concentrations and suspended fluxes are at greatest at the start of the uprush when the turbulence is maximum. Then the turbulence dissipates towards the end of the onshore flow, settling the suspended sediment to the bed. In contrast, the backwash is dominated by the sheet flow and bedload sediment transport. The flow velocity increases towards the end of the backwash causing more bed-generated turbulence, which results in sediment transport near the bed. The direction of the net sediment transport (onshore or offshore) is largely governed by the beachface gradient.
Longshore drift by swash occurs either due to beach cusp morphology or due to oblique incoming waves causing strong alongshore swash motion. Under the influence of longshore drift, when there is no slack-water phase during backwash flows, sediments can remain suspended to result in offshore sediment transport. Beachface erosion by swash processes is not very common but erosion can occur where swash has a significant alongshore component.
The swash zone is highly dynamic, accessible and susceptible to human activities. This zone can be very close to developed properties. It is said that at least 100 million people on the globe live within one meter of mean sea level. Understanding the swash zone processes and wise management is vital for coastal communities which can be affected by coastal hazards, such as erosion and storm surge. It is important to note that the swash zone processes cannot be considered in isolation as it is strongly linked with the surf zone processes. Many other factors, including human activities and climate change, can also influence the morphodynamics in the swash zone. Understanding the wider morphodynamics is essential in successful coastal management.
Construction of sea walls has been a common tool to protect developed property, such as roads and buildings, from coastal erosion and recession. However, more often than not, protecting the property by building a seawall does not achieve the retention of the beach. Building an impermeable structure such as a seawall within the swash zone can interfere with the morphodynamics system in the swash zone. Building a seawall can raise the water table, increase wave reflection and intensify turbulence against the wall. This ultimately results in erosion of the adjacent beach or failure of the structure. Boulder ramparts (also known as revetments or riprap) and tetrapods are less reflective than impermeable sea walls, as waves are expected to break across the materials to produce swash and backwash that do not cause erosion. Rocky debris is sometimes placed in front of a sea wall in the attempt to reduce the wave impact, as well as to allow the eroded beach to recover.
Understanding the sediment transport system in the swash zone is also vital for beach nourishment projects. Swash plays a significant role in transportation and distribution of the sand that is added to the beach. There have been failures in the past due to inadequate understanding. Understanding and prediction of the sediment movements, both in the swash and surf zone, is vital for the nourishment project to succeed.
The coastal management at Black Rock, on the north-east coast of Phillip Bay, Australia, provides a good example of a structural response to beach erosion which resulted in morphological changes in the swash zone. In the 1930s, a sea wall was built to protect the cliff from recession at Black Rock. This resulted in depletion of the beach in front of the sea wall, which was damaged by repeated storms in winter time. In 1969, the beach was nourished with approximately 5000m3 of sand from inland in order to increase the volume of sand on the beach to protect the sea wall. This increased the sand volume by about 10%, however, the sand was carried away by northward drifting in autumn to leave the sea wall exposed to the impacts of winter storms again. The project had failed to take the seasonal patterns of longshore drift into account and had underestimated the amount of sand to nourish with, especially on the southern part of the beach.
It is said that conduct of morphology research and field measurements in the swash zone is challenging since it is a shallow and aerated environment with rapid and unsteady swash flows. Despite the accessibility to the swash zone and the capability to take measurements with high resolution compared to the other parts of the nearshore zone, irregularity of the data has been an impediment for analysis as well as critical comparisons between theory and observation. Various and unique methods have been used for field measurements in the swash zone. For wave run-up measurements, for example, Guza and Thornton (1981, 1982) used an 80m long dual-resistance wire stretched across the beach profile and held about 3 cm above the sand by non-conducting supports. Holman and Sallenger (1985) conducted run-up investigation by taking videos of the swash to digitise the positions of the waterline over time. Many of the studies involved engineering structures, including seawalls, jetties and breakwaters, to establish design criteria that protect the structures from overtopping by extreme run-ups. Since the 1990s, swash hydrodynamics have been more actively investigated by coastal researchers, such as Hughes M.G., Masselink J. and Puleo J.A., contributing to the better understanding of the morphodynamics in the swash zone including turbulence, flow velocities, interaction with the beach groundwater table, and sediment transport. However, the gaps in understanding still remain in swash research including turbulence, sheet flow, bedload sediment transport and hydrodynamics on ultra-dissipative beaches.
Swash plays an important role as one of the instantaneous coastal processes and it is as important as the long-term processes such as sea level rise and geological processes in coastal morphodynamics. Swash zone is one of the most dynamic and rapidly changing environments on the coast and it is strongly linked with the surf zone processes. Understanding the swash mechanism is essential for the understanding of formation and changes of the swash zone morphology. More importantly, understanding of the swash zone processes is vital for society to manage coast wisely. There has been significant progress in the last two decades, however, gaps in understanding and knowledge in swash research still remain today.
Axial engines (sometimes known as barrel or Z-crank engines) are a type of reciprocating engine with pistons arranged around an output shaft with their axes parallel to the shaft. Barrel refers to the cylindrical shape of the cylinder group (result of the pistons being spaced evenly around the central crankshaft and aligned parallel to the crankshaft axis) whilst the Z-crank alludes to the shape of the crankshaft.
The key advantage of the axial design is that the cylinders are arranged in parallel around the output/crank shaft in contrast to radial and inline engines, both types having cylinders at right angles to the shaft. As a result, it is a very compact, cylindrical engine, allowing variation in compression ratio of the engine while running. In a swashplate engine the piston rods stay parallel with the shaft, and piston side-forces that cause excessive wear can be eliminated almost completely. The small-end bearing of a traditional connecting rod, one of the most problematic bearings in a traditional engine, is eliminated.
An alternate design, the Rand cam engine, replaces the plate with one or more Sinusoidal cam surfaces. Vanes mounted parallel to a shaft mounted inside a cylindrical 'barrel' that are free to sliding up and down ride the sinuous cam, the segments formed by rotor, stator walls and vanes constituting combustion chambers. In effect these spaces serving the same purpose as the cylinders of an axial engine, and the sinuous cam surface acts as the face of the pistons. In other respect this form follows the normal cycles of internal combustion but with burning gas directly imparting a force on the cam surface, translated into a rotational force by timing one or more detonations. This design eliminates the multiple reciprocal pistons, ball joints and swash plate of a conventional 'barrel' engine but crucially depends on effective sealing provided by sliding and rotating surfaces.
In either form the axial or 'barrel' engine can be derived as a cam engine or swashplate or wobble plate engine.
(A wobble-plate is similar to a swash plate, in that the pistons press down on the plate in sequence, imparting a lateral moment that is translated into rotary motion. This motion can be simulated by placing a Compact Disc on a ball bearing at its centre and pressing down at progressive places around its circumference. The difference is that while a wobble plate nutates, a swash-plate rotates.)
While axial engines are challenging to make practicable at typical engine operating speeds some cam engines have been tested that offer extremely compact size (approximating to a six-inch (150mm) cube) yet producing approximately forty horsepower at c 7000 rpm, useful for light aerial applications. The attraction of lightweight and mechanically simple (far fewer major moving parts, in the form of a rotor plus twelve axial vanes forming twenty-four combustion chambers) engines, even with a finite working life, have obvious application for small unmanned aircraft. (Such a design having allegedly been tested at NAVAIR PSEF in 2003.)Coastal morphodynamics
Coastal morphodynamics (i.e. the dynamics of beach morphology) refers to the study of the interaction and adjustment of the seafloor topography and fluid hydrodynamic processes, seafloor morphologies and sequences of change dynamics involving the motion of sediment. Hydrodynamic processes include those of waves, tides and wind-induced currents.
While hydrodynamic processes respond instantaneously to morphological change, morphological change requires the redistribution of sediment. As sediment takes a finite time to move, there is a lag in the morphological response to hydrodynamic forcing. Sediment can therefore be considered to be a time-dependent coupling mechanism. Since the boundary conditions of hydrodynamic forcing change regularly, this may mean that the beach never attains equilibrium. Morphodynamic processes exhibit positive and negative feedbacks (such that beaches can, over different timescales, be considered to be both self-forcing and self-organised systems), nonlinearities and threshold behaviour.
This systems approach to the coast was first developed by Wright and Thom in 1977 and finalized by Wright and Short in 1984. According to their dynamic and morphological characteristics, exposed sandy beaches can be classified into several morphodynamic types (Wright and Short, 1984; Short, 1996). There is a large scale of morphodynamic states, this scale ranges from the "dissipative state" to the "reflective extremes".
Dissipative beaches are flat, have fine sand, incorporating waves that tend to break far from the intertidal zone and dissipate force progressively along wide surf zones. Dissipative beaches are wide and flat in profile, with a wide shoaling and surf zone, composed of finer sediment, and characterised by spilling breakers.
Reflective beaches are steep, and are known for their coarse sand; they have no surf zone, and the waves break brusquely on the intertidal zone. Reflective beaches are typically steep in profile with a narrow shoaling and surf zone, composed of coarse sediment, and characterised by surging breakers. Coarser sediment allows percolation during the swash part of the wave cycle, thus reducing the strength of backwash and allowing material to be deposited in the swash zone
Depending on beach state, near bottom currents show variations in the relative dominance of motions due to: incident waves, subharmonic oscillations, infragravity oscillations, and mean longshore and rip currents. On reflective beaches, incident waves and subharmonic edge waves are dominant. In highly dissipative surf zones, shoreward decay of incident waves is accompanied by shoreward growth of infragravity energy; in the inner surf zone, currents associated with infragravity standing waves dominate. On intermediate states with pronounced bar-trough (straight or crescentic) topographies, incident wave orbital velocities are generally dominant but significant roles are also played by subharmonic and infragravity standing waves, longshore currents, and rips. The strongest rips and associated feeder currents occur in association with intermediate transverse bar and rip topographies.
Transitions between beach states are often caused by changes in wave energy, with storms causing reflective beach profiles to flatten (offshore movement of sediment under steeper waves), thus adopting a more dissipative profile. Morphodynamic processes are also associated with other coastal landforms, for example spur and groove formation topography on coral reefs and tidal flats in infilling estuaries.Demi Miller
Demi Miller is a fictional character from the BBC soap opera EastEnders, played by Shana Swash. She made her first appearance on 6 September 2004 and made her last on 7 July 2006 when she was axed by EastEnders executive producer Kate Harwood.Elm Tree Beacon Light
Elm Tree Beacon Light served as the front range with New Dorp Light as the rear to mark Swash Channel. The channel is now marked by Staten Island Light and West Bank Light.Joe Swash
Joseph Swash (born 20 January 1982) is an English presenter and actor, best known for his role of Mickey Miller in the BBC One soap opera EastEnders and various presenting roles with ITV2.Longshore drift
Longshore drift from longshore current is a geological process that consists of the transportation of sediments (clay, silt, pebbles, sand and shingle) along a coast parallel to the shoreline, which is dependent on oblique incoming wind direction. Oblique incoming wind squeezes water along the coast, and so generates a water current which moves parallel to the coast. Longshore drift is simply the sediment moved by the longshore current. This current and sediment movement occur within the surf zone.
Beach sand is also moved on such oblique wind days, due to the swash and backwash of water on the beach. Breaking surf sends water up the beach (swash) at an oblique angle and gravity then drains the water straight downslope (backwash) perpendicular to the shoreline. Thus beach sand can move downbeach in a zig zag fashion many tens of meters (yards) per day. This process is called "beach drift" but some workers regard it as simply part of "longshore drift" because of the overall movement of sand parallel to the coast.
Longshore drift affects numerous sediment sizes as it works in slightly different ways depending on the sediment (e.g. the difference in long-shore drift of sediments from a sandy beach to that of sediments from a shingle beach). Sand is largely affected by the oscillatory force of breaking waves, the motion of sediment due to the impact of breaking waves and bed shear from long-shore current. Because shingle beaches are much steeper than sandy ones, plunging breakers are more likely to form, causing the majority of long shore transport to occur in the swash zone, due to a lack of an extended surf zone.Mickey Miller
Mickey Miller is a fictional character from the BBC soap opera EastEnders, played by Joe Swash. He made his first appearance on 15 April 2003. Introduced as a guest character, Mickey proved popular and was turned into a regular by executive producer Louise Berridge. The character is portrayed as a wheeler-dealer, involved in various money-making scams. A family was built around the character in 2004 when the other Millers moved to Albert Square. It was announced on 25 February 2008 that the characters of Mickey and his stepfather Keith had been axed by EastEnders' executive producer Diederick Santer. Mickey left on 1 July 2008. In July 2011, it was announced Swash would reprise his role for the departure storyline of his screen brother Darren and appeared for two episodes on 19 and 20 September 2011.Rainbow Swash
The Rainbow Swash is the common name for an untitled work by Corita Kent in the Dorchester neighborhood of Boston, Massachusetts. The rainbow design painted on a 140-foot (43 m) tall LNG storage tank is the largest copyrighted work of art in the world. Highly visible from daily commuters' drives on Interstate 93, the landmark is considered one of the major landmarks of Boston, akin to the Citgo sign.Rosie Miller
Rosie Miller is a fictional character from the BBC soap opera EastEnders, played by Gerry Cowper. Her first appearance was 9 September 2004 and she was axed in 2006, with her final scenes airing July 2006.
Rosie is the mother of Mickey Miller (Joe Swash), Dawn Swann (Kara Tointon), Demi Miller (Shana Swash) and Darren Miller (Charlie G. Hawkins). Described as "hardworking", she is heavily protective over her family and makes enemies such as Pauline Fowler (Wendy Richard).S with swash tail
Ȿ (lowercase: ȿ) is a Latin letter s with a "swash tail" (encoded by Unicode, at codepoints U+2C7E for uppercase and U+023F for lowercase) that was used as a phonetic symbol by linguists studying African languages to represent the sound [sʷ].In 1931, it was adopted into the orthography of Shona for a 'whistled' s, but it was dropped in 1955 due to the lack of the character on typewriters and fonts. Today the digraph sv is used.Shana Swash
Shana Frances Swash (born 28 July 1990) is an English actress, and the sister of actor and TV presenter Joe Swash. She is best known for playing Demi Miller in the long-running BBC One soap opera EastEnders from 2004 to 2006.Stacey Solomon
Stacey Chanelle Claire Solomon (born 4 October 1989) is an English singer and television personality. She rose to fame on the sixth series of The X Factor, coming third overall on the show. She gained a number one single on both the UK Singles Chart and the Irish Singles Chart when her fellow The X Factor finalists released a cover of "You Are Not Alone".
Solomon won the tenth series of reality television show I'm a Celebrity... Get Me Out of Here! and was named "Queen of the Jungle". Her debut single, a cover of "Driving Home for Christmas", was released on 19 December 2011. Solomon released her debut album Shy on 18 April 2015, followed by the single "Shy".
Although Solomon was made famous by becoming a singer, she is now also a popular TV personality and presenter. In September 2016, she began appearing as a panellist on Loose Women and in November of the same year she began presenting I'm a Celebrity ITV2 spin-off show I'm a Celebrity...Get Me Out of Here!: Extra Camp alongside partner Joe Swash, Vicky Pattison and Chris Ramsey, though she did not return the following year.Surf zone
As ocean surface waves come closer to shore they break, forming the foamy, bubbly surface called surf. The region of breaking waves defines the surf zone. After breaking in the surf zone, the waves (now reduced in height) continue to move in, and they run up onto the sloping front of the beach, forming an uprush of water called swash. The water then runs back again as backswash. The nearshore zone where wave water comes onto the beach is the surf zone. The water in the surf zone, or breaker zone, is shallow, usually between 5 and 10 m (16 and 33 ft) deep; this causes the waves to be unstable.Swash (appliance)
Swash is a small home appliance marketed by the Whirlpool Corporation. It was first launched in September 2005 as the Whirlpool Fabric Freshener. The product is a steamer/dryer that through a patented technology uses distilled water to remove odors and wrinkles from garments and proposes saving money by reducing the number of required trips to the dry cleaners.
The Fabric Freshener was given an Industrial Design Excellence Award (IDEA) for Consumer Product in 2005.In its January 2006 issue, Good Housekeeping honored The Fabric Refresher with its prestigious "Good Buy" award. The award recognizes ground-breaking technology and innovation that makes people's lives easier.The Fabric Freshener has appeared or been mentioned on numerous television & print media avenues including the CBS Early Show, The Washington Post and The Wall Street Journal. In 2014 the Fabric Freshener was transferred from the Whirlpool line to its own brand named Swash.Swash (typography)
A swash is a typographical flourish, such as an exaggerated serif, terminal, tail, entry stroke, etc., on a glyph.
The use of swash characters dates back to at least the 16th century, as they can be seen in Ludovico Vicentino degli Arrighi's La Operina, which is dated 1522. As with italic type in general, they were inspired by the conventions of period handwriting. Arrighi's designs influenced designers in Italy and particularly in France.Swashbuckler
A swashbuckler is a heroic archetype in European adventure literature that is typified by the use of a sword, acrobatics and chivalric ideals. The archetype also became common as a film genre.Swashplate
A swashplate (also known as slant disk), invented by Anthony George Maldon Michell in 1917, is a device used in mechanical engineering to translate the motion of a rotating shaft into reciprocating motion, or vice versa. The working principles is similar to crankshaft, Scotch yoke, or wobble/nutator/Z-crank drives, in engine designs. It was originally invented to replace a crankshaft, and is one of the most popular concepts used in crankless engines.WASH
WASH (or Watsan, WaSH) is an acronym that stands for "water, sanitation and hygiene". Universal, affordable and sustainable access to WASH is a key public health issue within international development and is the focus of Sustainable Development Goal 6.Several international development agencies assert that attention to WASH can also improve health, life expectancy, student learning, gender equality, and other important issues of international development. Access to WASH includes safe water, adequate sanitation and hygiene education. This can reduce illness and death, and also reduce poverty and improve socio-economic development.
In 2015 the World Health Organization (WHO) estimated that "1 in 3 people, or 2.4 billion, are still without sanitation facilities" while 663 million people still lack access to safe and clean drinking water. In 2017, this estimate changed to 2.3 billion people without sanitation facilities and 844 million people without access to safe and clean drinking water.Lack of sanitation contributes to about 700,000 child deaths every year due to diarrhea, mainly in developing countries. Chronic diarrhea can have long-term negative effects on children, in terms of both physical and cognitive development. In addition, lack of WASH facilities can prevent students from attending school, impose an unusual burden on women and reduce work productivity.Z with swash tail
Ɀ (lowercase: ɀ) is a Latin letter z with a "swash tail" (encoded by Unicode, at codepoints U+2C7F for uppercase and U+0240 for lowercase) was used as a phonetic symbol by linguists studying African languages to represent a voiced labio-alveolar fricative ([zʷ]).In 1931, it was adopted into the orthography of Shona for a 'whistled' z, but it was dropped in 1955 due to the lack of the character on typewriters and fonts. Today the digraph zv is used.