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Wave Making Resistance
Wave-making resistance or wave resistance is a form of drag that affects any object moving on a surface of a fluid, such as boats and ships moving on the surface of water, and reflects the energy required to push the water out of the way of that body. For example, the hull of a moving watercraft creates waves (a wake) which carry energy away and resist the motion of the watercraft. Wave resistance is only one of the components of the total resistance or drag experienced by a body moving on a surface of a fluid, other being viscous drag and pressure drag. Physics background For small displacement hulls, such as sailboats or rowboats, wave-making resistance is the major source of the marine vessel drag. A salient property of water waves is dispersiveness; i.e., the greater the wavelength, the faster it moves. Waves generated by a ship are affected by her geometry and speed, and most of the energy given by the ship for making waves is transferred to water through the bow and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shock Wave
In physics, a shock wave (also spelled shockwave), or shock, is a type of propagating disturbance that moves faster than the local speed of sound in the medium. Like an ordinary wave, a shock wave carries energy and can propagate through a medium, but is characterized by an abrupt, nearly discontinuous, change in pressure, temperature, and density of the medium. For the purpose of comparison, in supersonic speed, supersonic flows, additional increased expansion may be achieved through an expansion fan, also known as a Prandtl–Meyer expansion fan. The accompanying expansion wave may approach and eventually collide and recombine with the shock wave, creating a process of destructive interference. The sonic boom associated with the passage of a supersonic aircraft is a type of sound wave produced by Wave interference, constructive interference. Unlike solitons (another kind of nonlinear wave), the energy and speed of a shock wave alone dissipates relatively quickly with distan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Speed–length Ratio
In continuum mechanics, the Froude number (, after William Froude, ) is a dimensionless number defined as the ratio of the flow inertia to the external force field (the latter in many applications simply due to gravity). The Froude number is based on the speed–length ratio which he defined as: \mathrm = \frac where is the local flow velocity (in m/s), is the local gravity field (in m/s2), and is a characteristic length (in m). The Froude number has some analogy with the Mach number. In theoretical fluid dynamics the Froude number is not frequently considered since usually the equations are considered in the high Froude limit of negligible external field, leading to homogeneous equations that preserve the mathematical aspects. For example, homogeneous Euler equations are conservation equations. However, in naval architecture the Froude number is a significant figure used to determine the resistance of a partially submerged object moving through water. Origins In o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluid Dynamics
In physics, physical chemistry and engineering, fluid dynamics is a subdiscipline of fluid mechanics that describes the flow of fluids – liquids and gases. It has several subdisciplines, including (the study of air and other gases in motion) and (the study of water and other liquids in motion). Fluid dynamics has a wide range of applications, including calculating forces and moment (physics), moments on aircraft, determining the mass flow rate of petroleum through pipeline transport, pipelines, weather forecasting, predicting weather patterns, understanding nebulae in interstellar space, understanding large scale Geophysical fluid dynamics, geophysical flows involving oceans/atmosphere and Nuclear weapon design, modelling fission weapon detonation. Fluid dynamics offers a systematic structure—which underlies these practical disciplines—that embraces empirical and semi-empirical laws derived from flow measurement and used to solve practical problems. The solution to a fl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stevens Institute Of Technology
Stevens Institute of Technology is a Private university, private research university in Hoboken, New Jersey. Founded in 1870, it is one of the oldest technological universities in the United States and was the first college in America solely dedicated to mechanical engineering. The 55-acre campus encompasses Landmarks of Hoboken, New Jersey#Castle Point, Castle Point, the highest point in Hoboken, a quad, and 43 academic, student and administrative buildings. Established through an 1868 bequest from Edwin Augustus Stevens, enrollment at Stevens includes more than 8,000 undergraduate and graduate students representing 47 states and 60 countries throughout Asia, Europe and Latin America. Stevens comprises three schools that deliver technology-based Science, technology, engineering, and mathematics, STEM (science, technology, engineering and mathematics) degrees and degrees in business, arts, humanities and social sciences: The Charles V. Schaefer Jr., School of Engineering and Sci ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hull Speed
Hull speed or displacement speed is the speed at which the wavelength of a vessel's bow wave is equal to the waterline length of the vessel. As boat speed increases from rest, the wavelength of the bow wave increases, and usually its crest-to-trough dimension (height) increases as well. When hull speed is exceeded, a vessel in displacement mode will appear to be climbing up the back of its bow wave. From a technical perspective, at hull speed the bow and stern waves interfere constructively, creating relatively large waves, and thus a relatively large value of wave drag. Ship drag for a displacement hull increases smoothly with speed as hull speed is approached and exceeded, often with no noticeable inflection at hull speed. The concept of hull speed is not used in modern naval architecture, where considerations of speed/length ratio or Froude number are considered more helpful. Background As a ship moves in the water, it creates standing waves that oppose its movement. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wave-piercing
A wave-piercing boat hull has a very fine bow, with reduced buoyancy in the forward portions. When a wave is encountered, the lack of buoyancy means the hull pierces through the water rather than riding over the top, resulting in a smoother ride than traditional designs, and in diminished mechanical stress on the vessel. It also reduces a boat's wave-making resistance. Design theory calls for very long thin hulls, so in practice most are multi-hulls such as catamarans and trimarans. The main current usage areas are passenger ferries and naval ship A naval ship (or naval vessel) is a military ship (or sometimes boat, depending on classification) that is used by a navy. Naval ships are differentiated from civilian ships by construction and purpose. Generally, naval ships are damage resili ...s. See also * * * , later renamed MY ''Ady Gil'' * * * , a pioneer of the design * * Norwegian Cruise Line -Class Cruise Ships * hull form * * * : an racing multihull * : h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acceleration
In mechanics, acceleration is the Rate (mathematics), rate of change of the velocity of an object with respect to time. Acceleration is one of several components of kinematics, the study of motion. Accelerations are Euclidean vector, vector quantities (in that they have Magnitude (mathematics), magnitude and Direction (geometry), direction). The orientation of an object's acceleration is given by the orientation of the ''net'' force acting on that object. The magnitude of an object's acceleration, as described by Newton's second law, is the combined effect of two causes: * the net balance of all external forces acting onto that object — magnitude is Direct proportionality, directly proportional to this net resulting force; * that object's mass, depending on the materials out of which it is made — magnitude is Inverse proportionality, inversely proportional to the object's mass. The International System of Units, SI unit for acceleration is metre per second squared (, \ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Supertanker
An oil tanker, also known as a petroleum tanker, is a ship designed for the bulk transport of oil or its products. There are two basic types of oil tankers: crude tankers and product tankers. Crude tankers move large quantities of unrefined crude oil from its point of extraction to refineries. Product tankers, generally much smaller, are designed to move refined products from refineries to points near consuming markets. Oil tankers are often classified by their size as well as their occupation. The size classes range from inland or coastal tankers of a few thousand metric tons of deadweight (DWT) to ultra-large crude carriers (ULCCs) of . Tankers move approximately of oil every year.UNCTAD 2006, p. 4. Second only to pipelines in terms of efficiency,Huber, 2001: 211. the average cost of transport of crude oil by tanker amounts to only US. Some specialized types of oil tankers have evolved. One of these is the naval replenishment oiler, a tanker which can fuel a moving vess ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Planing (sailing)
Planing ( ) is the mode of operation for a waterborne craft in which its weight is predominantly supported by lift (force), hydrodynamic lift, rather than Hydrostatics, hydrostatic lift (buoyancy). Many forms of marine transport make use of planing, including High-speed craft, fast ferries, racing boats, seaplanes, and water skis. Most surfboards are planing or semi-planing hulls. Beyond planing, fast vessel designs have seen a transition to hydrofoil designs. History The earliest documented planing sailboat was a proa built in 1898 by Commodore Ralph Munroe#Vessels designed, Ralph Munroe. It was capable of speeds of more than twice the hull speed. Planing a sailing Dinghy sailing, dinghy was first popularised by Uffa Fox in Britain. In 1928 Fox introduced planing to the racing world in his International 14 dinghy, ''Avenger''. That year he gained 52 first places, 2 seconds, and 3 third places out of 57 race starts. This performance was noticed by other designers who further ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lift (force)
When a fluid flows around an object, the fluid exerts a force on the object. Lift is the Euclidean_vector#Decomposition_or_resolution, component of this force that is perpendicular to the oncoming flow direction. It contrasts with the drag (physics), drag force, which is the component of the force parallel to the flow direction. Lift conventionally acts in an upward direction in order to counter the force of gravity, but it is defined to act perpendicular to the flow and therefore can act in any direction. If the surrounding fluid is air, the force is called an aerodynamic force. In water or any other liquid, it is called a Fluid dynamics, hydrodynamic force. Dynamic lift is distinguished from other kinds of lift in fluids. Aerostatics, Aerostatic lift or buoyancy, in which an internal fluid is lighter than the surrounding fluid, does not require movement and is used by balloons, blimps, dirigibles, boats, and submarines. Planing (boat), Planing lift, in which only the lower po ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bow Wave
A bow wave is the wave that forms at the bow (watercraft), bow of a ship when it moves through the water. As the bow wave spreads out, it defines the outer limits of a ship's Wake (physics), wake. A large bow wave slows the ship down, is a risk to smaller boats, and in a harbor can damage shore facilities and moored ships. Therefore, Hull (watercraft), ship hulls are generally designed to produce as small a bow wave as possible. Description The size of the bow wave is a function of the speed of the ship, its Draft (hull), draft, Ocean surface wave, surface waves, water depth, and the shape of the bow. A ship with a large Draft (hull), draft and a blunt bow will produce a large wave, and ships that Planing (sailing), plane over the water surface will create smaller bow waves. Bow wave patterns are studied in the field of computational fluid dynamics. The bow wave carries energy away from the ship at the expense of its kinetic energy—it slows the ship. A major goal of naval arch ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
