Drag Forces Flashcards
Define Fluid Flow
Is the study of fluids in motion, the way liquids and gas as move or flow.
What is Total Drag?
Total Drag = Pressure drag + Wave drag
What is Pressure Drag?
It concerns the breaking away or separating of a flow of water or air when a body move through it. (AKA form drag)
What is Pressure Differential?
The pressure at one point is different from the pressure at another. in sport this difference created lift and spin.
What is Boundary Layer?
The immediate layer of fluid near the surface of an object as a fluid moves over it.
Factors affecting pressure drag?
- Cross section of the body at right angles to the flow - Shape and position of the body - Smoothness of the surface Eg. bmx helmet and cyclist helmet.
What is Slipstreaming?
The pressure drag on a runner increases with a increase in velocity. the air pressure in the front of each runner is higher than the pressure in the turbulent wake at their back.
Sporting example of Pressure Drag?
A. swimmer hanging down in the water has a larger drag force. B. swimmer lying flatter in the water has a lesser drag force.
What is Surface Drag?
It is the friction in the surface of a body as it moves though liquid. (AKA friction drag or skin friction) Eg. Surface drag in swimming - athletes shave off all visible hair to reduce surface drag.
What is Wave Drag?
Disturbance at the surface of the fluid that creates waves which resist motion. Eg. When a swimmer moves though or under the water, it produces waves. reduced by being streamlined.
