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- Fluid Mechanics-2 - FM2
- 2017
- PYQ
**Biju Patnaik University of Technology BPUT - BPUT**- Mechanical Engineering
- B.Tech
**269 Views**- 7 Offline Downloads
- Uploaded 1 year ago

Registration no: Total Number of Pages: 02 B.Tech PEME5402 7th Semester Regular / Back Examination 2017-18 Advanced Fluid Mechanics BRANCH: Mech Time: 3 Hours Max Marks: 70 Q.CODE: B412 Answer Question No.1 which is compulsory and any five from the rest. The figures in the right hand margin indicate marks. Q1 Answer the following questions: a) Water temperature in an open container changes from T=200C at top to T=100C at bottom. Is the water continuous with respect to temperature and density? b) Is it necessary to invoke stokes hypothesis for incompressible flow? Explain. c) D For incompressible flow, 0 . Does it mean that is constant in the Dt flow? Explain. d) For a two dimensional flow V 2 x 2 yi 2 yx 2 j . Does it represent a possible flow? Is velocity potential defined here e) For steady, inviscid, incompressible and irrotational flow, Bernoulli’s equation is applicable only along stream line. True/False? Explain. f) In most of the cases flow is viscous. In this regard, does the study of potential flow (inviscid flow) theory have any relevance? g) In a fully developed laminar flow through a pipe, the shear stress on the centerline is zero. Can Bernoulli’s equation be applied along the pipe centre line? h) A cylinder is dragged sidewise towards right and is made to rotate clockwise in a fluid medium. What will be the direction of the Lift force i.e. upward or down ward? Explain. i) Define stagnation pressure for incompressible and compressible flow. j) What is Euler’s equation? 1 (2 x 10)

Q2 a) What is Prandtl's mixing length theory ? explain b) 1 4 The elements of stress tensor at a point is given as .Can the 4 3 continuum in which this tensor exists be a fluid? Explain. (5) (5) Q3 a) Derive the Navier Stokes equations for compressible flow. b) e If e r ez in cylindrical coordinates, evaluate V . r r z (5) (5) Q4 a) Show that stress tensor is symmetric even if there is an external couple on the fluid element b) A long pipe is connected to a large reservoir that initially is filled with water to a depth of 3m. The pipe is 150mm in diameter and 6m long. Determine the flow velocity leaving the pipe as a function of time after the cap is removed from its free end. Assume the flow to be frictionless and incompressible. State any other assumptions clearly. Q5 a) Explain the Hagen-Poiseuille flow. b) Explain the Karman's velocity defect law. (5) Q6 a) Derive an equation for the speed of the sound in a medium and show (5) (5) (5) (5) that for an ideal gas, C RT , where C is the speed of sound and is the ratio of specific heats. b) Explain the Hiemenz flow. (5) Q7 Consider the flow between two horizontal porous plates y=H and y=-H, driven by an axial pressure gradient. Fluid is injected at the bottom plate with a constant velocity Vw. The fluid suction velocity at the top is also Vw. Assume that the vertical velocity is V=Vw everywhere. Derive an ordinary differential equation for the axial velocity in the porous channel. Solve this differential equation to determine the axial velocity profile. You may assume that no slip boundary condition is valid for the porous plates. Q8 Write short answer on any TWO: a) b) c) d) Lagrangian description of flow Plane Poiseuille flow Strain rate tensor Universal velocity distribution. 2 (10) (5 x 2)

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