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Topic: Wave drag


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In the News (Thu 18 Jul 19)

  
  Volume Wave Drag
For conceptual design, we may add wave drag of the fuselage and the wave drag of the wing with a term for interference that depends strongly on the details of the intersection.
For the first estimate in AA241A we simply add the wave drag of the fuselage based on the Sears-Haack results and volume wave drag of the wing with a 15% mark-up for interference and non-optimal volume distributions.
For first estimates of the volume-dependent wave drag of a wing, one may create an equivalent ellipse and use closed-form expressions derived by J.H.B. Smith for the volume-dependent wave drag of an ellipse.
adg.stanford.edu /aa241/drag/volumedrag.html   (584 words)

  
 Aerodynamic Drag, Viscous, Wave, Interference, Lift-Induced
From a physical point of view, drag is the resultant of forces acting normally and tangentially to a surface, the former ones being pressure terms, and the latter ones viscous terms.
Drag due to lift is the result of the downwash (vertical flow) and to the strength of the vortices produced at some particular locations (wing tips or other sharp edges) of many lifting systems.
Wave drag is created by radiation of disturbances in the fluid by a moving body.
aerodyn.org /Drag/drag.html   (798 words)

  
 What is Drag?
Drag is generated by the difference in velocity between the solid object and the fluid.
Drag is a force and is therefore a vector quantity having both a magnitude and a direction.
The component of the aerodynamic force that is opposed to the motion is the drag; the component perpendicular to the motion is the lift.
www.grc.nasa.gov /WWW/K-12/airplane/drag1.html   (817 words)

  
 Minimum Wave Drag, Sears-Haack Body, von Karman Ogive
Drag at supersonic speeds include the drag components at subsonic flow conditions (skin friction drag and induced drag) and a wave drag, characteristic of supersonic flows only.
The wave drag is on turns divided in (wave) drag due to volume and (wave) drag due to lift.
The Sears-Haack body is a slender body of revolution pointed at both ends, that corresponds to the minimum wave drag (for given volume and length) of a linear distribution of sources at supersonic speeds.
aerodyn.org /Drag/super-drag.html   (290 words)

  
  Multihull Maven
Skin friction drag is caused by the tendency of water to cling to the hull and to itself.
Wave drag is the reason that a submarine has less resistance in a dive than is does when cruising on the surface, even though the wetted area will be less.
When the length of the wave is equal to the length of the boat the influences from bow, midsections and stern combine to generate a large wave with a peak at the bow and stern.
www.multihull-maven.com /How_fast_will_she_go?   (841 words)

  
  drag
Drag is generated by nine conditions associated with the motion of air particles over an aircraft.
Because skin friction drag is an interaction between a solid (the airplane surface) and a gas (the air), the magnitude of skin friction drag depends on the properties of both the solid and the gas.
Generally, interference drag will add to the component drags but in a few cases, for example, adding tip tanks to a wing, total drag will be less than the sum of the two component drags because of the reduction of induced drag.
www.daviddarling.info /encyclopedia/D/drag.html   (1185 words)

  
 Drag
Drag is a force caused by the dynamic action of a fluid that acts in the direction of the freestream fluid flow.
The drag force is computed using the coefficient of drag, the fluid density, the projected area of the body or the surface area of the body oriented perpendicular to the fluid flow, and is the relative velocity of the body with respect to the fluid.
Several factors affect the magnitude of form drag, including the relative velocity of the body with respect to the fluid, the magnitude of the pressure gradient between the front and rear ends of the body, and the size of the surface area that is aligned perpendicular to the flow.
www.columbia.edu /ccnmtl/draft/soup/inst_web/drag.html   (2141 words)

  
 chapt5
Drag was composed of three main components- skin-friction drag, pressure drag, and induced drag (or drag due to lift).
This wave drag is due to the unstable formation of shock waves which transforms a considerable part of the available propulsive energy into heat, and to the induced separation of the flow from the airplane surfaces.
Thin airfoils: The wave drag rise associated with transonic flow is roughly proportional to the square of the thickness-chord ratio (t/c).
history.nasa.gov /SP-367/chapt5.htm   (3022 words)

  
 chapt5
Drag was composed of three main components- skin-friction drag, pressure drag, and induced drag (or drag due to lift).
This wave drag is due to the unstable formation of shock waves which transforms a considerable part of the available propulsive energy into heat, and to the induced separation of the flow from the airplane surfaces.
Thin airfoils: The wave drag rise associated with transonic flow is roughly proportional to the square of the thickness-chord ratio (t/c).
www.hq.nasa.gov /office/pao/History/SP-367/chapt5.htm   (3022 words)

  
 Training
In the top panel the bow wave is in synchrony with the stern wave inducing reinforcement of wave formation; in the bottom panel the bow wave cancels the stern wave (after Carlton 1994).
It remains to be determined whether wave drag and thus total drag may be diminished by improving the swimming technique as was suggested previously (Counsilman, 1968; Bober and Czabanski, 1975; Maglischo, 1982; Toussaint and Beek, 1992).
In effect, measurement of wave amplitudes of swimmers revealed that the amplitude of the bow wave was smaller than halve the amplitude of the stern wave.
www.ifkb.nl /B4/techniqueanddra2.html   (1088 words)

  
 Aerodynamic Drag, Viscous, Wave, Interference, Lift-Induced
From a physical point of view, drag is the resultant of forces acting normally and tangentially to a surface, the former ones being pressure terms, and the latter ones viscous terms.
Drag due to lift is the result of the downwash (vertical flow) and to the strength of the vortices produced at some particular locations (wing tips or other sharp edges) of many lifting systems.
Wave drag is created by radiation of disturbances in the fluid by a moving body.
www.aerodyn.org /Drag/drag.html   (798 words)

  
 Textbook
To minimize friction drag on an aircraft all the sheets of metal on the wing join smoothly, and even the rivets are rounded over and as flush with the surface as possible.
Induced drag or drag due to lift is a small amount of excess (lift) force generated in the opposite direction of the lift force along a wing.
Wave drag is caused by the interactions of shock waves over the vehicle and the pressure losses due to the shocks.
wings.avkids.com /Tennis/Book/drag-01.html   (692 words)

  
 Coaches' Information Service: The "Fast-Skin" Body Suit: Hip, hype, but does it reduce drag during front crawl swimming?   (Site not responding. Last check: )
Apart from pressure drag, the swimmer is subjected to friction drag (Ff), attributed to the forces tending to slow the water flowing along the surface of a swimmer's body.
The magnitude of the friction drag depends on the velocity of the flow relative to that of the body, the surface area of the body, and the characteristics of the surface.
And second, the drag reduction achieved with the artificial coatings are less than 10%, enough to create excitement in the hypercompetitive world of boat racing, enough perhaps to make a difference to fitness in the competitive world of pelagic predation, but nothing approaching the difference in skin friction between laminar and turbulent flows.
www.coachesinfo.com /article/index.php?id=146&style=printable   (3747 words)

  
 Sonic Boom, Sound Barrier, and Prandtl-Glauert Condensation Clouds   (Site not responding. Last check: )
As the speed of of an object increases, the drag force, and therefore the power required to maintain or increase the speed, suddenly and strongly increases as the sound speed is approached.
Because the shock waves and their drag are not present in subsonic flight, i.e., flight at speeds below the speed of sound, there will be an additional source of drag and power loss which will need to be accounted for when the aircraft is designed.
A second contribution to the drag associated with the sound barrier is due to the fact that the disturbance due to the wing and even the generation of lift will cause shock waves to appear in the flow.
www.fluidmech.net /tutorials/sonic/soundbarrier.htm   (1000 words)

  
 Transonic Flow
At subsonic speeds, drag was composed of three main components—skin-friction drag, pressure drag, and induced drag (or drag due to lift).
This wave drag is due to the unstable formation of shock waves that transforms a considerable part of the available propulsive energy into heat, and to the induced separation of the flow from the airplane surfaces.
The total drag at transonic and supersonic speeds can be divided into two categories: (1) zero-lift drag composed of skin-friction drag and wave (or pressure-related) drag of zero lift and (2) lift-dependent drag composed of induced drag (drag due to lift) and wave (or pressure-related) drag due to lift.
www.centennialofflight.gov /essay/Theories_of_Flight/Transonic_Flow/TH19.htm   (1663 words)

  
 Drag - WOI Encyclopedia Italia
For a solid object moving through a fluid or gas, drag is the sum of all the aerodynamic or hydrodynamic forces in the direction of the external fluid flow.
Beyond these two kinds of drag there is a third kind of drag, called wave drag, that occurs when the solid object is moving through the fluid at or near the speed of sound in that fluid.
The overall drag of an object is characterized by a dimensionless number called the drag coefficient, and is calculated using the drag equation.
www.wheelsofitaly.com /wiki/index.php/Drag   (242 words)

  
 Untitled
The program had to be able to represent drag which originated from skin friction, from the forcing apart of the volume of water through which the hull moved (form, or profile, drag), and from the generation of waves on the water surface.
There are three main sources of the drag on a boat hull, namely skin friction (due to the roughness of the hull surface), form drag (due to the effort required to force the flow apart, as the hull moves through the water) and wave drag.
However, wave drag is due energy which is radiated away, as the waves generated by the hull propagate outward.
members.iinet.net.au /~bluep/wavedrag.html   (1771 words)

  
 The Drag Equation
Drag depends on the density of the air, the square of the velocity, the air's viscosity and compressibility, the size and shape of the body, and the body's inclination to the flow.
The drag equation states that drag D is equal to the drag coefficient Cd times the density r times half of the velocity V squared times the reference area A.
Determining the value of the drag coefficient is more difficult than determining the lift coefficient because of the multiple sources of drag.
exploration.grc.nasa.gov /education/rocket/drageq.html   (502 words)

  
 The Drag Coefficient
The drag coefficient is a number that engineers use to model all of the complex dependencies of shape and flow conditions on rocket drag.
The drag coefficient then expresses the ratio of the drag force to the force produced by the dynamic pressure times the area.
At supersonic speeds, shock waves will be present in the flow field and we must be sure to account for the wave drag in the drag coefficient.
exploration.grc.nasa.gov /education/rocket/dragco.html   (505 words)

  
 Wave drag (George Herbert)
For both types, there's a general equation where drag is equal to half of the wetted area times the density of seawater times square of velocity times the coeficient of drag.
A ship has a local minimum in energy lost to waves as it moves at a speed at which a deep (or shallow, if appropriate) water wave wavelength is the length of the hull.
Hull shape (and presence or absence of a bow bulb, and block coeficient, and...) greatly affects the wave drag coeficient.
yarchive.net /mil/wave_drag.html   (628 words)

  
 Met Office: Gravity wave drag
The total drag depends on the wind speed, density and static stability of the low-level flow, where the low-level flow is that layer of air which intersects the sub-grid orography.
The drag calculation accounts for the shape (anisotropy) of the sub-grid orography by orienting the drag vector to be perpendicular to the major axis of the sub-grid orography.
The total drag is partitioned into low-level flow-blocking and gravity-wave drag components depending on the low-level Froude number.
www.metoffice.com /research/nwp/numerical/physics/gravity.html   (159 words)

  
 Drag
Pressure drag results from the large eddies or swirls of air caused by an objects that presents are large surface area to the direction of flow.
Friction drag results from the friction between fluid and the object and is highest when the most surface is exposed to the fluid.
The cost of creating this wave, lifting the water, is taken into account by the drag augmentation factor, X. For example, if the drag on the animal increases by 100% due to gravitational wave factor we multiply our energy equation by a factor of 2, X = 2.
www.zoology.ubc.ca /courses/bio325/Drag.html   (312 words)

  
 III
The parameterization of gravity wave drag (GWD) is based on simplified theoretical concepts and observational evidence.
The parameterization consists of determines the drag due to gravity waves at the surface and its vertical variation.
The parameterization of the drag at the surface is based on the formulation described by Pierrehumbert (1987) and Helfand et al.
grads.iges.org /agcm/agcm_pbl.html   (1015 words)

  
 Drag
Drag is a resistance force generated by a solid object moving through a fluid.
Drag must be overcome by thrust in order to achieve forward motion.
Drag is generated by nine conditions associated with the motion of air particles over the aircraft.
www.centennialofflight.gov /essay/Theories_of_Flight/drag/TH4.htm   (1272 words)

  
 Drag Reduction Using Counterflow Jet Injection
Designers must seriously consider the large wave drag on an air or space vehicle's aerodynamic design due to the increase in entropy across the shock wave surrounding the body in high-speed flight.
However, the vehicle's total drag reduction can be as small as 5-10% after scientists take into consideration the percentage contribution of the nose drag reduction to the total drag of the vehicle and the complexity of the potential configuration.
Scientists observed a drag reduction of 30-40%, depending on the operating stagnation pressure, in the experimental studies for a Mach 5.85 flow past a hemisphere cylinder.
www.afrlhorizons.com /Briefs/Mar02/VA0102.html   (1297 words)

  
 Met Office: Gravity wave drag
The total drag depends on the wind speed, density and static stability of the low-level flow, where the low-level flow is that layer of air which intersects the sub-grid orography.
The drag calculation accounts for the shape (anisotropy) of the sub-grid orography by orienting the drag vector to be perpendicular to the major axis of the sub-grid orography.
The total drag is partitioned into low-level flow-blocking and gravity-wave drag components depending on the low-level Froude number.
www.metoffice.gov.uk /research/nwp/numerical/physics/gravity.html   (159 words)

  
 Pocock Racing Shells, 1-888-POCOCK1
Friction drag is the wet area of the boat dragging against the molecules of the water.
Wave drag, of course, is the resistance due to waves being made at the interface of the air and water.
It is widely believed that 80-90 percent of racing shells’ hydrodynamic drag is simple skin friction and that wave drag is the major part of the remaining 10-20 percent.
www.pocock.com /askbill.html   (871 words)

  
 Meridian International Research - Supersonic
The current approaches to sonic boom minimisation do not seek to eliminate the shock wave, but to shape or flatten the rise time of the N wave signature at ground level so that it is less objectionable.
The best solution is to eliminate the shock wave and to prevent it from forming in the first place, so that we eliminate both the sonic boom and its associated wave drag.
Wave Modelling approach and the Electrostatic Theory of Aerodynamics to design a vehicle not for boom reduction but to prevent the boom from forming in the first place.
www.meridian-int-res.com /Aeronautics/SSonic.htm   (2479 words)

  
 Ocean Physics University of Otago, New Zealand
Drag measurements from a towed mannequin show total drag at the surface is up to 2.4 times the drag when fully immersed.
This additional drag is due to the energy required to form waves in the wake behind the mannequin.
Comprehensive measurements spanning human swimming speeds and tow depths up to 1.0m demonstrate that wave drag on the mannequin is less than 5% of total drag for tows deeper than 0.5m at 1m/s and 0.7m at 2m/s.
www.otago.ac.nz /marinescience/po/projects/wavedrag.htm   (295 words)

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