Mechanics of Fluids Mid - II, November - 2014

1.The boundary layer separation exists on the surface when
  • du/dy = 0 and dp/du = 0
  • du/dy = 0 and dp/dx > 0
  • du/dy = 0 and dp/dx < 0
  • None
Answer: B
2.The drag provided by end effect due to finite length of an aerofoil is
  • Form drag
  • Profile drag
  • Induced drag
  • Boundary drag
Answer: C
3.The head loss in a sudden expansion from 6 cm diameter pipe to 12 cm diameter pipe in terms of velocity V1 is the smaller diameter pipe is
Answer: D
4.The Prandtl mixing length is
  • Independent of shear stress
  • zero at the pipe wall
  • Independent of distance from the fixed surface
  • Constant for all fluids
Answer: B
5.Which of the following bend will cause maximum head loss
  • 300 bend
  • 600 bend
  • 900 bend
  • U bend
Answer: C
6.Co-efficient of velocity contraction and discharge arranged in increasing order of
  • Cv Cc Cd
  • Cd Cc Cv
  • Cv Cd Cc
  • Cc Cd Cv
Answer: B
7.Ratio of inertia force to viscous force is known as
  • Renold’s number
  • Froude number
  • Mach number
  • Euler number
Answer: A
8.Model analysis of a pipe flow is based on
  • Renold’s number
  • Froude number
  • Mach number
  • Euler number
Answer: A
9.Buckingham theorem stipulate that the number of dimensional groups
  • n-m
  • m-n
  • n+m
  • n/m
Answer: A
10.The loss of head due to sudden contraction of a pipe
Answer: A
11.The co-efficient of drag for turbulent flow over the cylinder is _______ than that for laminar flow because separation is delayed.
Answer: Less
12.Flow around sphere at very low Reynold’s number is governed by the _________________
Answer: Stoke’s law
13.Momentum transfer is on molecular level in flow.
Answer: Laminar
14.The velocity distribution in turbulent flow is given approximately by Prandtl’s _______________
Answer: One seventh power law
15.If the Reynold’s number is used for model and prototype using the same liquid then the discharge ratio is __________
Answer: 1
16.Froude number is used in the study of ________________ flow
Answer: Fee surface
17.Boundary layer thickness ___________________ along with the flow direction.
Answer: Increases
18.At the separation point of boundary layer the velocity gradient will be __________________
Answer: Zero
19.Flow in a pipe is laminar when Reynold’s number is __________________
Answer: Less than 2000
20.Frictional resistance of a pipe varies approximately with the ___________________ of the liquid
Answer: Square of velocity