Fluid Mechanics Midterm #3

body forces

act throughout the entire body of the CV

surface forces

act on the CS

free stream velocity

the velocity of the fluid approaching a body

streamlined body

a body whose shape is aligned with the anticipated streamlines in the flow

bluff or blunt body

a body that tends to block the flow

velocity boundary layer

the region of the flow above the solid surface bounded by delta in which the effects of the viscous shearing forces caused by fluid viscosity are felt

drag

components of the pressure and the wall shear forces in the direction parallel to the flow

lift

the components of the pressure and wall shear forces in the direction normal to the flow

frontal area

front area that the free stream velocity ineracts with first

planform area

the area seen by a person looking at the body from above in a direction normal to the body, used for thin bodies

skin friction drag

part of drag directly due to wall shear stress

pressure drag

part of drag directly due to pressure

separated region

a low-pressure region behind the body where recirculating and backflows occur

wake

low pressure region of flow trailing the body where the effects of the body on velocity are felt

creeping flow

flow at a very low Reynolds number (less than 10)

vortices

the formation and shedding of circulating fluid structures

vortex shedding

the period generation of vortices downstreamsta

stall

massive flow separation leading to a dramatic loss of lift and increase in drag