"In fluid dynamics, drag (sometimes called fluid resistance) is a force acting opposite to the relative motion of any object moving with respect to a surrounding fluid."
Force exerted by a fluid on an object moving through it, opposite to the direction of motion.
Newton's laws: The three laws of motion that govern the behavior of fluids and objects in motion.
Aerodynamics and hydrodynamics principles: The science that explains how fluids (air and water) behave when they flow around or through an object.
Reynolds number: A dimensionless number that is used to characterize the flow behavior of a fluid.
Flow regimes: The different types of flow regimes in which a fluid may exist, including laminar, transitional, and turbulent flows.
Boundary layer: A thin layer of fluid that forms at the surface of an object and that experiences different flow behavior than the bulk fluid.
Drag coefficient: A dimensionless parameter that relates the drag force on an object to the object's size, shape, and velocity.
Pressure drag: A type of drag that is caused by the pressure differences that occur around an object as a fluid flows past it.
Friction drag: A type of drag that is caused by the frictional forces that exist between the fluid and the object's surface.
Separation: The phenomenon that occurs when the flow of a fluid around an object becomes unstable, leading to a separation of the fluid from the object's surface.
Viscosity: A property of fluids that describes their resistance to deformation or flow.
Wake: The region of disturbed flow that occurs behind an object as a fluid flows past it.
Drag reduction techniques: Methods that can be used to reduce the amount of drag that an object experiences, such as streamlining and the use of special coatings.
Skin drag: It is the frictional force that is experienced by the fluid particles near the surface of a body that is moving in a fluid.
Form drag: This drag is due to the shape of the body and the resulting differences in pressure distribution around the body.
Pressure drag: This drag is caused by the decrease in pressure behind a body moving through a fluid.
Lift-induced drag: This drag results from the production of lift on a body, which causes a drag force to be produced opposite the direction of the lift force.
Wave drag: This drag is generated by the presence of waves on the surface of a body moving at a high speed through a fluid.
Turbulent drag: Turbulence in a fluid results in fluid particles moving in chaotic patterns. This type of drag is produced due to this turbulence.
Viscous drag: This drag is due to the viscosity of the fluid, which is defined as the resistance of the fluid to flow.
Separation drag: In some cases, the flow of fluid around a body can separate from the body, resulting in a drag force being produced.
Interference drag: When two bodies are in close proximity to each other, the flow of fluid around each body can be affected by the other body, resulting in additional drag force.
Compressibility drag: This drag results from the fact that as a body moves through a fluid at high speeds, the fluid becomes compressed and its density is increased, resulting in a drag force being produced.
"Unlike other resistive forces, such as dry friction, which are nearly independent of velocity, the drag force depends on velocity."
"Drag force is proportional to the velocity for low-speed flow and the squared velocity for high-speed flow, where the distinction between low and high speed is measured by the Reynolds number."
"This can exist between two fluid layers (or surfaces) or between a fluid and a solid surface."
"Drag forces always tend to decrease fluid velocity relative to the solid object in the fluid's path."
"Drag (sometimes called fluid resistance)"
"The drag force depends on velocity."
"No, unlike other resistive forces like dry friction, the drag force depends on velocity."
"The distinction between low and high speed is measured by the Reynolds number."
"Yes, drag force can exist between two fluid layers (or surfaces)."
"Yes, drag force can exist between a fluid and a solid surface."
"The distinction between low and high speed is measured by the Reynolds number."
"Yes, drag force is a force acting opposite to the relative motion of any object."
"Drag forces always tend to decrease fluid velocity relative to the solid object in the fluid's path."
"Drag is a force in fluid dynamics."
"Drag force can exist in any surrounding fluid."
"The paragraph does not provide information about the dependence of drag force on the shape or size of the object."
"For high-speed flow, the drag force is proportional to the squared velocity."
"The Reynolds number is used to differentiate between low-speed and high-speed flow, which determines the behavior of drag force."
"Yes, drag forces are forces acting on objects moving with respect to a surrounding fluid."