Search results
Results from the WOW.Com Content Network
In aerodynamics, aerodynamic drag, also known as air resistance, is the fluid drag force that acts on any moving solid body in the direction of the air's freestream flow. [ 23 ] From the body's perspective (near-field approach), the drag results from forces due to pressure distributions over the body surface, symbolized D p r {\displaystyle D ...
Drag coefficients in fluids with Reynolds number approximately 10 4 [1] [2] Shapes are depicted with the same projected frontal area. In fluid dynamics, the drag coefficient (commonly denoted as: , or ) is a dimensionless quantity that is used to quantify the drag or resistance of an object in a fluid environment, such as air or water.
drag force F d. Using the algorithm of the Buckingham π theorem, these five variables can be reduced to two dimensionless groups: drag coefficient c d and; Reynolds number Re. That this is so becomes apparent when the drag force F d is expressed as part of a function of the other variables in the problem:
A particular aircraft may have different curves even at the same R e and M values, depending for example on whether undercarriage and flaps are deployed. [2] Drag curve for light aircraft. C D0 = 0.017, K = 0.075 and C L0 = 0.1. The tangent gives the maximum L/D point. The accompanying diagram shows C L against C D for a typical light aircraft.
For Reynolds numbers below about 1 the dependence is linear, above 1000 (turbulent flow) it becomes quadratic. In air, which has a kinematic viscosity / around 0.15 cm 2 /s, this means that the drag force becomes quadratic in v when the product of object speed and diameter is more than about 0.015 m 2 /s, which is typically the case for ...
The aerodynamic force is the resultant vector from adding the lift vector, perpendicular to the flow direction, and the drag vector, parallel to the flow direction. Forces on an aerofoil . In fluid mechanics , an aerodynamic force is a force exerted on a body by the air (or other gas ) in which the body is immersed, and is due to the relative ...
Stokes' law is important for understanding the swimming of microorganisms and sperm; also, the sedimentation of small particles and organisms in water, under the force of gravity. [5] In air, the same theory can be used to explain why small water droplets (or ice crystals) can remain suspended in air (as clouds) until they grow to a critical ...
Forces of flight on a powered aircraft in unaccelerated level flight. Understanding the motion of air around an object (often called a flow field) enables the calculation of forces and moments acting on the object. In many aerodynamics problems, the forces of interest are the fundamental forces of flight: lift, drag, thrust, and weight. Of ...