Fluid Mechanics And Machinery January 11, 2019 Vijayan 0 Fluid Mechanics and Machinery features exhaustive coverage of the essential concepts of the mechanics of fluids, both static and dynamic. It also provides an overview of the design and operation of various hydraulic machines such as pumps and turbines. Which among the following cannot be used as an alternative term for a “solenoidal vector field”? Incompressible vector field Divergence- free vector field Continuous random field Transverse vector field Navier- Stokes equation describes the motion of Solid substance Viscous fluid Non-viscous fluid Gas Froude number depends upon_____ Characteristic length and volume Flow velocity and mass Mass flow rate and volume Flow velocity, external field and characteristic length What is the Mach number at room temperature? 340 m/s 310 m/s 320 m/s 330 m/s Ratio of duct length to width length in a compressibel flow is a______ Less than or equal to 5 More than or equal to 5 More than 5 Less than 5 The fluid speed through the nozzle is altered with_____ Deceleration Acceleration Constant speed Zero What happens to velocity in the diverging duct? Decrease Increase Same Independent Find the kinematic viscosity of oil having density 1962 g/m3. the force experienced for area of 20 m2 is 4.904 kN and velocity of gradient at that point is 0.2/s 0.625 1.25 2.5 None of the mentioned The velocity distribution for fluid flow over a flat plate is given by u=2y-6y2 in which u is the velocity in metre per second at a distance of y metre above the plate. Determine the shear stress at y=0.15m.Take dynamic viscosity of fluid as 8.6 poise. 0.172 N/m2 0.344 N/m2 0.086 N/m2 None of the mentioned A beaker contains water up to a certain height as shown. If the water is allowed to get discharged through a small pipe (of a uniform diameter), what type of flow will it be in the pipe? steady and uniform steady and non-uniform unsteady and uniform unsteady and non-uniform What type of flow can be taken for granted in a pipe of a uniform cross-section? steady unsteady non-uniform uniform Which of the following is true? Flow is laminar both inside and outside of the boundary layer Flow is laminar inside the boundary layer and turbulent outside Flow is turbulent both inside and outside of the boundary layer Flow is turbulent inside the boundary layer and laminar outside Capillarity fall is reduced if we take the appartus (capillary tube immersed in fluid having acute angle of contact) considerable distance inside the earth( i.e below the earth crust). True False The swirl caused due to eddies are called as____ Volume Velocity Vortices Vertices The flow of fluid along curvillinear or curved path is known as_____ Curvillinear flow Circular flow Sink flow Vortex flow When external torque is absent the type of vortex flow is Circular vortex flow Independent vortex flow Free vortex flow None of the mentioned Maximum achievable velocity of a gas is directly proportional to_____ Velocity Deceleration Pressure Specific heat Which among the following is a device that converts a laminar flow into a turbulent flow? Dead weight gauge Ionizing gauge Turbulator Vacuum gauge Boundary layer seperation does not undergo detachment? True False With the boundary layer separation, displacement thickness________ Remains same Independent Decrease Increase What is the unit for flow rate of gases? m3/s kgf/s litres/s cm3/s What are the assumptions made for a fluid flow through a pipe? Mass is not considered Fluid inertia is not taken Viscosity is not taken Volume is not considered A soap film is trapped between a frame and a wire of length 10 cm as shown in figure.If the surface tension is given as 0.0049 N/m, what will be the value of m (in mg) such that the wire remains in equilibrium? 10 0.1 100 1 What is D’Alembert’s Paradox? Pressure gradient= 0 Resistance= 0 Drag force= 0 Temperature = 0 Continuum mechanics is a branch of mechanics that deals with________ Fluid particles Discrete particles Hydrostatic Pressure Kinematics and mechanical behaviour The drag coefficient of a complete structure such as an aircraft include____ Form drag Pressure drag Interference drag Induced drag Pump converts mechanical energy into ________ Pressure energy Kinetic energy Potential energy Pressure and kinetic energy The Navier- Stokes equation can be used in which of the following applications? Automobiles Ocean Currents Airplanes Thermometer Which is following a high pressure pump? Centrifugal pump Reciprocating pump Rotary pump Ionization pump Which of following is not a dimensionless number? Mach Cartesian Froude Reynolds How do we measure flow rate of liquid? Coriolis method Dead weight method Conveyor method Ionization method Skin friction acts on the components of____ Vane angles Surface blade Profile drag Parallel movement For a streamlined body to achieve low drag coefficient, the boundary layer must____ Flow over the body Be attached to the body Move away from the body Move parallel to the body Which among the following is not an example of magneto fluid? Plasma Alcohol Salt water Liquid metals What is the incompressibility condition in Navier-Stokes equation? ∇.u=0 ∇.u>0 ∇.u<0 ∇.u=1 The viscous force the relative motion between the adjacent layers of a fluid in motion. Which one of the flowing fits best in the sentence? May effect under certain condition Never affects Opposes Facilitates Which one of the following is the CGS unit of dynamic viscosity? Poise m2/s Stokes Pa-s What type of flow is obtained by superimposing two definite flow types{( considering ideal condition) Potential Ideal Both are correct None of these The principle of floatation of bodies is based on the premise of Newtons first law Metacentre Newtons law of viscosity None of these Which one of the following is not a unit of dynamics viscosity? N-s/m2 Stokes Pa-s Poise Which of the following correctly states how the viscosities of a liquid and a gas will change with temperature? Viscosity increases with the increase in temperature of a liquid and increases with the increase in temperature of a gas Viscosity decreases with the increase in temperature of a liquid and decreases with the increase in temperature of a gas Viscosity increases with the increase in temperature of a liquid and decreases with the increase in temperature of a gas Viscosity decreases with the increase in temperature of a liquid and increases with the increase in temperature of a gas A soap bubble of d mm diameter is observed inside a bucket of water. If the pressure inside the bubble is 0.075 N/cm^{2}, what will be the value of d? (Take surface tension as 0.075 N/m) 1.6 mm 0.4 mm 0.6 mm 0.8 mm The metacentric height is affected by the change in density. True False A uniform body of size 4 m long * 2.5 m wide * 1.5 m deep floats in water. What is the weight of the body if depth of immersion is 1 m ? 147.1 kN 294.3 kN 73.5 kN 588.6 kN The nature of streamlines in a flow net obtained by the combination of source and sink is___ Circular Random Linear Curvillinear Potential lines for the source-sink pair will be eccentric non intersecting circles with their centers on the axis True False What is the term used for a case where source and sink( both of them are of equal magnitude) approach each other such, distance between them reduces and product of distance and discharge magnitude remains constant A plain pair A doublet source in unifor Hagen Poiseuille flow Coutte flow What is the characteristic of stagnation point Velocity is zero Acceleration is unifor Both are correct None of these Which one of the following is unit of specific weight? N = m2 N = m N = m3 N = ms Two fluids 1 and 2 have mass densities of p1 and p2 respectively. If p1 > p2, which one of the following expressions will represent the relation between their specific volumes v1 and v2? v1 > v2 v1 < v2 v1 = v2 Cannot be determined due to insufficient information. We can draw Mohr’s circle for a fluid at rest True False In the equation for steam function due to source steam function is inversely proportional to magnitude at discharge True False Stream of doublet flow are family of circles tangent to a common axis? True False A beaker is filled with a liquid up to the mark of one litre and weighed. The weight of the liquid is found to be 6.5 N. The specific weight of the liquid will be 6:5 kN = m3 6:6 kN = m3 6:7 kN = m3 6:8 kN = m3 The specific gravity of liquid has__ the same unit as that of mass density the same unit as that of weight density the same unit as that of specific volume no unit The specific volume of a liquid is the reciprocal of___ weight density mass density specific weight specific volume Which among the following is the correct formula to find out the shear modulus(G)? E/2(1+v) E/2 v/2 2E(1+v) Which among the following is a formula for shear stress? τ = F/m τ = F*A τ = F/A τ = F*m Hooke’s law is applicable within what limit? Fracture point Elastic limit Ultimate strength Plastic limit The Prandtl Number approximates ____ Thermal diffusivity to momentum diffusivity Momentum diffusivity to thermal diffusivity Shear stress to thermal diffusivity Thermal diffusivity to kinematic viscosity

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