1 Foundation of Fluid Mechanics
35
Fig. 1.38 Boundary layer development under variable pressure gradient
Fig. 1.39 Boundary layer separation around circular cylinder flow
the wall is found, thus finding a new way to solve the problem of viscous flow
and playing an epoch-making milestone role.
Prandtl found through a large number of experiments that although the
Re number of the whole flow is very large, the characteristics of the flow field
are far from the ideal flow in the thin layer fluid near the surface, and there
is a large velocity gradient along the normal direction, so the viscous force
cannot be ignored. Prandtl calls the thin layer near the surface where the
viscous force plays an important role in the boundary layer. The introduction
of the concept of boundary layer opens a new way for people to take into
35
Fig. 1.38 Boundary layer development under variable pressure gradient
Fig. 1.39 Boundary layer separation around circular cylinder flow
the wall is found, thus finding a new way to solve the problem of viscous flow
and playing an epoch-making milestone role.
Prandtl found through a large number of experiments that although the
Re number of the whole flow is very large, the characteristics of the flow field
are far from the ideal flow in the thin layer fluid near the surface, and there
is a large velocity gradient along the normal direction, so the viscous force
cannot be ignored. Prandtl calls the thin layer near the surface where the
viscous force plays an important role in the boundary layer. The introduction
of the concept of boundary layer opens a new way for people to take into