Fluid Mechanics - Mechanical Engineering (MCQ) questions and answers for Q. 3948

Q.  The velocity gradients over the boundary layer are
- Published on 04 Aug 15

a. small
b. large
c. sometimes small and sometimes large
d. cannot say

ANSWER: large


  • Pankaj   -Posted on 05 Oct 15
    The velocity of fluid at boundary is zero when boundary surface is stationary. As the fluid passes the solid object, the molecules right next to the surface stick to the surface.

    Deceleration of each layer of fluid from the boundary makes the flow velocity higher away from the boundary layer. This creates a thin layer of fluid near surface in which velocity changes from zero to full stream velocity.

    Therefore the velocity gradients over the boundary layer are large.

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