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The friction drag force, which is a tangential force on the aircraft surface, depends substantially on boundary layer configuration and viscosity. The net friction drag, , is calculated as the downstream projection of the viscous forces evaluated over the body's surface.
The force on an object that resists its motion through a fluid is called drag. When the fluid is a gas like air, it is called aerodynamic drag or air resistance. When the fluid is a liquid like water it is called hydrodynamic drag, but never "water resistance". Fluids are characterized by their ability to flow.
20 Οκτ 2022 · It’s the study of how air flows around a car and how that affects its performance. There are two types of airflow: laminar and turbulent. Laminar airflow is smooth and predictable, while turbulent airflow is chaotic and unpredictable. Laminar vs Turbulent flow.
4 Μαρ 2017 · However, one must remember that in a very thin layer (called the boundary layer—shown by δ) near the vehicle surface there is a so-called “skin friction” which also adds to the drag coefficient (but its contribution in automobiles to C D is usually very small).
At highway speeds, over 50 % 50 % of the power of a car is used to overcome air drag. The most fuel-efficient cruising speed is about 70–80 km/h (about 45–50 mi/h). For this reason, during the 1970s oil crisis in the United States, maximum speeds on highways were set at about 90 km/h (55 mi/h).
21 Νοε 2022 · Friction drag happens because it takes energy to make layers of air slide past one another. The rougher or more obstructive the object, the more turbulent the air flow becomes, the greater the friction between the layers, and the greater the drag.
The air that sticks to the surface of a car creates a drag force due to skin friction. Pressure drag is created when the shape of the surface changes abruptly, as at the point where the roof of an automobile ends.
