Understanding Aerodynamic Drag

What are the two components into which a drag force can be divided?

• Thrust and lift

• Lift and weight

• Pressure drag and friction drag

• Shear stress and pressure stress

What causes wall shear stresses?

• Turbulence in the fluid

• The object's speed through the fluid

• Frictional forces due to fluid viscosity

• Pressure differences around the object

Why is pressure drag significant for blunt bodies?

• Because of their low surface area

• Due to a difference in pressure at the front and rear

• Because of the high velocity gradients

• Due to their streamlined shape

How do dimples on a golf ball reduce drag?

• By creating a laminar flow

• By delaying flow separation

• By reducing the surface area

• By increasing pressure drag

Why is it challenging to maintain laminar flow over aircraft wings?

• Due to the transition to turbulent flow

• Because of the air's viscosity

• Due to the shape of the wings

• Because of the high speeds involved

What is the primary goal of Hybrid Laminar Flow Control?

• To increase pressure drag

• To increase turbulence

• To delay the onset of turbulence

• To reduce the object's weight

What effect does shark skin have on the boundary layer of water?

• Causes flow separation

• Reduces friction drag

• Increases turbulence

• Increases pressure drag

What does the drag coefficient (C-D) capture?

• Only the shape of the object

• The fluid's density and velocity

• Hard-to-measure parameters like flow regime effects

• The object's weight and surface area

What happens to the drag coefficient of a sphere at very low Reynolds numbers?

• It increases significantly

• It remains constant

• It is inversely proportional to the Reynolds number

• It decreases

What is Stokes' Law used to calculate?

• The pressure drag on an object

• The terminal velocity of a sphere in fluid

• The lift force on an airplane wing

• The viscosity of a fluid