In a turbulent flow, the velocity of the liquid molecules in contact with the walls of the tube is:

Explanation

The no-slip condition requires that the fluid relative velocity at the solid boundary equals the wall velocity. For a stationary wall, the velocity of fluid at the wall is zero even in turbulent flow. This is because the no-slip boundary condition applies to viscous fluids: the fluid velocity at the wall equals the wall velocity even in turbulence. If the wall is stationary, the instantaneous fluid velocity at the wall is zero. (Turbulence causes fluctuating velocities away from the wall, but the instantaneous velocity at the wall still equals the wall velocity).