Homework1:Laminar Boundary Layer Flow
Yan Sheng
1.Introduntion
The boundary layer is a thin layer in the high Reynolds number flow,which
contains the sticky force of the sticky surface,also known as the flow boundary layer.
The viscous flow over a flat plate is sketched in Figure 1, the flow velocity is zero at
the surface because of the no-slip condition.As the flow moves away from the surface,
the flow velocity increases in the y direction until it equals to freestream velocity
which will occur at a specific height.Usually,δ is defined as the distance above the
plate surface where u=0.99u
e
, Here u
e
is the velocity at the trailing edge of the
boundary layer.And δ is called the velocity boundary thickness.At a given x, the
variation of u between y=0 and y=δ, that is u=u(y), is called the velocity profile
within the boundary layer.
Figure1. Velocity Boundary Layer
Nomenclature
u = horizontal velocity
v = vertical velocity
μ = viscous ratio
Re = Reynolds number
υ = kinetic viscous ratio
δ = boundary layer thickness
c_f = skin friction coefficient