Here's a breakdown:
* Hydrodynamic drag: The resistance encountered by an object moving through a fluid (like water or air).
* Viscous drag: The component of drag caused by the fluid's viscosity (its resistance to flow). This is the force that directly pushes the fluid out of the way.
Examples:
* A fish swimming: The fish's streamlined shape and its movements minimize viscous drag, allowing it to move through the water efficiently.
* An airplane flying: The wings of an airplane are designed to create lift and minimize viscous drag, allowing the plane to stay aloft.
* A car driving: The shape of a car affects how much air it pushes out of the way. Aerodynamic designs minimize viscous drag, improving fuel efficiency.
Key Concepts:
* Fluid viscosity: The thicker the fluid, the more resistance it offers to motion.
* Object shape: Streamlined shapes minimize viscous drag, while blunt shapes cause more fluid displacement.
* Velocity: The faster the object moves, the higher the viscous drag.
The act of moving fluid out of the way is a complex process involving multiple factors, but the term viscous drag specifically describes this aspect of hydrodynamic drag.
