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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. [ 22 ] 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.
Terminal velocity is the maximum speed attainable by an object as it falls through a fluid (air is the most common example). It is reached when the sum of the drag force ( F d ) and the buoyancy is equal to the downward force of gravity ( F G ) acting on the object.
The Buckingham pi theorem then leads to a third dimensionless group, the ratio of the relative velocity to the speed of sound, which is known as the Mach number. Consequently when a body is moving relative to a gas, the drag coefficient varies with the Mach number and the Reynolds number.
The two main factors that impact drag are the frontal area of the vehicle and the drag coefficient. The drag coefficient is a unit-less value that denotes how much an object resists movement through a fluid such as water or air. A potential complication of altering a vehicle's aerodynamics is that it may cause the vehicle to get too much lift.
This term dominates the low-speed side of the graph of lift versus velocity. Drag curve for light aircraft. The tangent gives the maximum L/D point. Form drag is caused by movement of the body through air. This type of drag, known also as air resistance or profile drag varies with the square of speed (see drag equation). For this reason profile ...
Johann Bernoulli [clarification needed] took up this challenge and soon thereafter solved the problem and air resistance varied as "any power" [verification needed] of velocity; [clarification needed] known as the Bernoulli equation. [verification needed] This is the precursor to the concept of the "standard projectile". [14]
If correctly selected, it reaches terminal velocity, which can be measured by the time it takes to pass two marks on the tube. Electronic sensing can be used for opaque fluids. Knowing the terminal velocity, the size and density of the sphere, and the density of the liquid, Stokes' law can be used to calculate the viscosity of the fluid. A ...