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Fluid Mechanics (321-340)

Updated: Apr 23, 2020

321. regarding specific energy of the flow in an open channel:Consider the following statements

Alternate depths are the depths of flow at which the specific energy is

the same

Critical flow occurs when the specific energy is minimum.


322. Which of the following equations are used for the derivation of the differential

equation for water surface profile in open channel flow ?

Continuity equation ,Energy equation


323. S profile can occur at a break in slope from mild to steep

a break in slope from mild to steep


324. In a standing wave flume, the depth of flow in the throat region

should be equal to the critical depth


325 Property which explains the spherical shape of the drop of a liquid-Surface tension Property which explains the phenomenon of cavitaion in a fluid flow-Vapour pressure Property which explains the rise of sap in a tree-Capillarity Property which explains the flow of a jet of oil in an unbroken stream-Viscosity


326. An inclined plate 2 m long and 1 m wide lies with its length inclined at 45° to the surface of water and the nearest edge 1 m below it. If the specific weight of water is 1000 kg/m³, then the total pressure on the plate (in kg.) is approximately.



327. A rectangular floating body 20 m long is 5 m wide. The water line is 1.5 m above the bottom. If the centre of gravity is 1.8 m from the bottom, then its metacentric height will be approximately 0.34 m


328. The constant angular velocity at which a liquid rotates in a cylinder about a vertical axis such that the pressure at a point on the axis is the same as at a point 2 m higher at a radius 2 m is √g


329. Flow net is drawn for a two-dimensional boundary. The velocity of uniform flow at approach is 1.2 m/s. The size of the square is 1.2 cm side. The size of the square at another location in the stream tube is 0.5 cm. The velocity at this point is

2.88 m/s


330. If the velocity, bulk modulus of elasticity and the mass density of afluidare denoted by U, K and ρ respectively, then the Mach number is given by




332. Assuming that the thrust T of a propeller depends on the diameter D, speed of advance V, angular velocity ω, dynamic viscosity μ and mass density p, which of

the following non can dimensional parameters be derived by Dimensional Analysis


333. A river model is constructed to a horizontal scale of 1:1000 and a vertical

scale of 1:100. If the model discharge were 0.1 m³/s, then the discharge in the

river (in m³/s) would b 10


334. If δ1 and δ2 denote the boundary layer thicknesses at a point distance x from the leading edge on a flat plate when the Reynolds numbers are 100 and 256

respectively, then the ratio of δ1 to δ2 will be 1.6


335. The lift formula is given by Lift = ρV Γ, where ρ is the density of the fluid, V, the free stream velocity and Γ, the circulation. Given the following conditions

two-dimensional steady flow,incompressible flow,body of any shape


336. A long pipeline carries water from a river to a city. As part of an augmentation

scheme, a similar pipe is added in parallal to the existing pipe for half the total length of the pipeline. The percentage increase in discharge will be 26


337 at any junction of a loop, the total inflow is equal to the total outflow

at any junction, loss of head in clockwise branch is equal to the loss of head in anti-clockwise branch


338. A penstock is 3000 metres long. Pressure wave travels in it with a velocity of 1500m/s. If the turbine gates are closed uniformly and completely in a period of

4.5 seconds, then it is called slow closure


339. Water flows uniformly down a 30° slope in a very rough channel at a normal depth of 8 cm. The intensity of bed shear in kgf/m² will be about 40


340. The sequent depth ratio in a hydraulic jump formed in a horizontal rectangular channel is 16.48. The Froude number of the super-critical stream is


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