drag coefficient

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drag coefficient

A student calculates the drag coefficient of a model car in a wind tunnel.

Definition
  1. Noun:
    • A dimensionless number: The drag coefficient is a dimensionless number that quantifies the drag or resistance of an object in a fluid environment, such as air or water.
    • A ratio in fluid dynamics: It is specifically defined as the ratio of the drag force experienced by a body moving through a fluid to the product of the fluid's dynamic pressure and the body's reference area.
Usage
  • The drag coefficient is a critical parameter in aerodynamics and automotive design for predicting the resistance an object will encounter.
  • Engineers work to minimize a vehicle's drag coefficient to improve fuel efficiency and top speed.
  • The drag coefficient is typically represented by the symbols , , or .
Examples
  • Noun:
    • A streamlined car body has a lower drag coefficient than a boxy truck.
    • The drag coefficient of a smooth sphere is approximately 0.47.
    • Calculating the precise drag coefficient is essential for designing efficient aircraft wings.
Advanced Usage
  • "Cd value": A common way to refer to the numerical value of the drag coefficient.
    • The new model boasts a remarkably low Cd value of 0.24.
  • "Coefficient of drag": A full, alternative name for the drag coefficient.
    • The coefficient of drag is a major focus in Formula 1 aerodynamics.
Variants and Related Words
  • Drag force (n): The actual resistance force experienced by the object moving through the fluid.
    • The drag force increases with the square of the velocity.
  • Lift coefficient (n): A similar dimensionless number quantifying the lift generated by an object like an airfoil.
    • The wing's design optimizes both the lift coefficient and the drag coefficient.
Synonyms
  • Coefficient of drag: (Formal synonym)
  • Cd: (Abbreviated form, used primarily in technical contexts)
  • Air resistance coefficient: (A descriptive synonym, though less precise)
Related Phrases
  • To have a high/low drag coefficient: Describes the magnitude of the coefficient.
    • Parachutes are designed to have a very high drag coefficient.
  • Drag coefficient reduction: The process or goal of lowering the Cd value.
    • Drag coefficient reduction was the primary goal of the vehicle's redesign.
drag coefficient

A student calculates the drag coefficient of a model car in a wind tunnel.

Noun
  1. the ratio of the drag on a body moving through air to the product of the velocity and the surface area of the body

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