Aerodynamic Drag

Also found in: Dictionary.

aerodynamic drag

[‚e·ro·dī′nam·ik ′drag]
(fluid mechanics)
A retarding force that acts upon a body moving through a gaseous fluid and that is parallel to the direction of motion of the body; it is a component of the total fluid force acting on the body. Also known as aerodynamic resistance.

Aerodynamic Drag


head drag, a force which a gas (for example, air) exerts on a body moving through it; this force is always directed opposite to the direction of velocity and is a component of the aerodynamic force. Knowledge of aerodynamic drag is necessary for aerodynamic calculations of aircraft, since, in particular, the speed of motion for given thrust characteristics of an engine installation depends on this knowledge.

Aerodynamic drag is the result of the irreversible transformation of a portion of the kinetic energy of a body into heat. Aerodynamic drag depends on the shape and dimensions of the body, on its angle of attack, on the magnitude of velocity, and also on the properties and conditions of the medium in which motion takes place. In actual mediums there is viscous friction in the boundary layer between the surface of the body and the medium, and there are losses in the formation of shock waves at transonic and supersonic velocities (wave drag) and in the formation of vortices. The predominant component of aerodynamic drag depends on the flight conditions and shape of the body. For example, for blunt bodies of rotation moving at a high supersonic velocity, aerodynamic drag is determined mainly by wave drag. For streamlined bodies moving at a low velocity, aerodynamic drag is determined by friction drag and by losses in the formation of vortices.

In aerodynamics, aerodynamic drag is described by a nondimensional aerodynamic drag coefficient CD, through which the aerodynamic drag D is defined as

where ρ∞ is the density of the undisturbed medium, v∞ is the velocity of motion of the body relative to this medium, and 5 is the specific area of the body. The coefficient CD for a body of a given shape at a particular orientation relative to the flow depends on the non-dimensional similarity criteria, which include Mach numbers and Reynolds numbers. The numerical value of CD is usually determined experimentally, by measuring the aerodynamic drag in wind tunnels and in other devices used in aerodynamic experiments. Aerodynamic drag may be determined theoretically only for a limited class of the simplest bodies.


References in periodicals archive ?
Due to aerodynamic lift being very sensitive to car body boundary layer, it is thought that the precision of the simulation results for aerodynamic lift would be limited by the reasons mentioned above, while the simulation results of aerodynamic drag usually could meet the request of practice application, testified by the most of cases.
In gasoline vehicles, where the engine and powertrain parts and their cooling modules are usually located under the hood, front-end cooling is one of the major constraints for reducing aerodynamic drag of the vehicle.
The results presented show significant potential for aerodynamic drag and emissions reductions of police cars.
Greenhouse Gas Emissions Model (GEM) is used to determine relative fuel economy savings from aerodynamic drag [8, 9, 10].
Aerodynamic drag will increase in the bargain, and maximum airspeed will decrease slightly, perhaps five knots or so.
Since they took away the horsepower, it gives you some of that acceleration back because you have less aerodynamic drag.
It follows the Audi"Aerosthetics" concept, combining technical measures for reducing aerodynamic drag with creative design solutions.
e dynamic, coupe-like design is formed around Jaguar's aluminiumintensive architecture and combines the outstanding proportions, elegant surfaces and perfect lines which dene all Jaguar cars, with a longer wheelbase, more interior space and exceptionally low aerodynamic drag.
The dynamic, coupelike design is formed around Jaguar's aluminium-intensive architecture and combines the outstanding proportions, elegant surfaces and perfect lines which define all Jaguar cars, with a longer wheelbase, more interior space and exceptionally low aerodynamic drag yet in a lower and shorter body than the car it replaces.
The wing mirrors have been repositioned to the A pillars, to put them closer to the eye line of the driver and reduce aerodynamic drag, while the trailing edge of the door-mounted radiator channels have been extended to draw more air down through the cavity within the door, and into the engine to aid cooling, it said.
Here is a capsule summary of the status of the 787-9 and 787-10 programs: Boeing said the Hybrid Laminar Flow Control system on the tail fin and horizontal stabilizer of the 787-9 produced "significant" reduction in aerodynamic drag in testing, but the company declined to be specific.
Using this technique, in December 2012, Yokohama Rubber developed its fin tire design, which reduces aerodynamic drag on a vehicle by controlling the air flow in the wheel well.