Integration Of Momentum Equation Research Articles

On The Integration of Momentum Equation with Boundary Layer Suction.(Dept.M)

Boundary layer suction is one of the effective methods for the prevention of flow separtion. In this paper, a method is introduced to integrate the momentum equation, in which the suction velocity is assumed constant, and the velocity gradient varies. This particular type of flow can be used to form an estimate of the quantities of air that must be sucked on an aerofoil, so that separation of flow does not take place. In this case, although the boundary layer is very thin before separation, the velocity gradient may be very large, and it is obvious that only small quantites of air withdrawn are sufficient to delay the stall.

Mean sediment concentration and turbulent boundary layer of wave-induced sheet flow

A mathematical model describing mean sediment concentration and turbulent boundary layer of wave-induced sheet flow is presented. The interaction of the fluid and sediment in two-phase flow is considered. The diffusion coefficient and eddy viscosity are respectively expressed as functions of gradient Richardson number, which measures the effect of suspended sediment on turbulent transfer of mass and momentum. Computational results reveal that the presence of suspended sediments retards mean velocity profile and its corresponding phase shift. The friction factor which differs from rough wall law is obtained from the integration of momentum equation. An explicit expression based on the approximation of friction factor is given to define the region where sheet flow occurs. Observations in the laboratory provide support for the validity of this criterion. The predicted mean concentration profile is compared favorably with measurements.