The Convection Boundary layers Velocity Boundary Layer Free stream 6(x Velocity boundary a For fluid flow over a flat plate which disturbs the fluid flow Asy→>∞:u= u where u is velocity in X-direction As y>0: u=0(no-slip condition) The boundary layer thickness is defined as the value at which: u(y)=0.99u The boundary layer thickness 8 varies with x Shear Stress Dynamic viscosity 0 Local friction coefficient Heat Transfer Su Yongkang School of Mechanical EngineeringHeat Transfer Su Yongkang School of Mechanical Engineering # 9 The Convection Boundary Layers Velocity Boundary Layer • For fluid flow over a flat plate, which disturbs the fluid flow: – As y→: where u is velocity in x-direction – As y→0: (no-slip condition) – The boundary layer thickness is defined as the value at which: – The boundary layer thickness  varies with x • Shear Stress • Local friction coefficient =0   = y s y u           =  2 2 u C s f   u = u u = 0 = u u(y) 0.99 Dynamic viscosity