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.

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