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34 Fundamentals of Fluid Mechanics & Hydraulic Machinery- FM Lab Viva

34 Fundamentals of Fluid Mechanics & Hydraulic Machinery- FMHM Lab Viva: Fundamentals of Fluid Mechanics plays a vital role when you are going for an interview in a core company. They will ask you all the basic concepts of FMHM including the basic equations. If you are perfect in all these aspects, then they will ask from Material Science. So, when you are planning for an interview prepare well all the concepts of Material Science. Considering that, I had collected all the 34 Fundamentals of Fluid Mechanics & Hydraulic Machinery which will be helpful to you in both the aspects. One is for the case of Interview and the other is to pass the Viva of FMHM Lab.

34 Fundamentals of Fluid Mechanics & Hydraulic Machinery- FM Lab Viva
34 Fundamentals of Fluid Mechanics & Hydraulic Machinery- FM Lab Viva

34 Fundamentals of Fluid Mechanics & Hydraulic Machinery:

The 34 Fundamentals of Fluid Mechanics are presented below in the form of Table of contents and whichever definition you need, just click on it.

S.NOFundamentals of Fluid Mechanics(Table of Contents)
1Q

2Q

3Q

4Q

5Q

6Q

7Q

8Q

9Q

10Q

11Q

12Q

13Q

14Q

15Q

16Q

17Q

18Q

19Q

20Q

21Q

22Q

23Q

24Q

25Q

26Q

27Q

28Q

29Q

30Q

31Q

32Q

33Q

34Q

 

What is fluid?

What is density?

What is specific weight or weight density?

What is specific gravity?

What is bulk modulus?

What is ideal fluid?

What is viscosity?

What is Newtonian fluid?

What is surface tension?

What is pressure?

What is capillarity?

What are the different types of non-newtonian fluids?

What is Steady flow?

What is unsteady flow?

What is Rotational or Irrotational flow?

What is the Path line?

What is the streak line?

What is continuity equation?

What is Vorticity?

What is the Potential Function?

What is the Stream Function?

Instruments used to measure the discharge, velocity, specific gravity and humidity?

What is hammering effect?

What is Archimedes principle?

What is boundary layer zone?

What is Bernoulli’s equation?

What is Total Energy Line?

What is Hydraulic Gradient Line?

What is Velocity head?

What is syphon flow?

What is displacement thickness?

What is Momentum thickness?

What is Energy thickness?

What are the different types of flows in a circular pipe,parallel plate, open channel and Over a sphere(through soil/earth)?

The Detailed explanation of 34 Fundamentals of Fluid Mechanics is presented below in a detailed manner.

FLUID MECHANICS VIVA

1Q.What is fluid?

Ans: It is a substance which deforms continuously for a small amount of shear force also whereas solids cannot deform with a small amount of shear force and thereby they can’t come under fluids.

 

2Q.What is density?

Ans: It is defined as the ratio of the mass of the substance to the volume of the substance.It is denoted by ρ.

ρ =m/v

Units = Kg/m3

 

3Q.What is specific weight or weight density?

Ans: It is defined as the ratio of the volume of the substance to the weight of the substanc e.It is also the reciprocal of density. It is denoted by ‘γ’

 

4Q.What is specific gravity?

Ans. It is defined as the ratio of the density of any fluid to the density of the reference fluid. It is denoted by “S”.

Sliq = ρ(any fluid)/ρ(water)

 

5Q.What is bulk modulus?

Ans: It is defined as the ratio of direct stress acting on a body to the volumetric strain. It is denoted by K.

K = direct stress / volumetric strain

 

6Q.What is ideal fluid?

Ans: It is a fluid having all ideal properties like no viscosity, no surface tension, incompressible, irrotational, etc.if this condition is satisfied then it is called as an ideal fluid.

Note: Bulk modulus for ideal fluid is infinity.

 

7Q.What is viscosity?

Ans: It is the property of fluid by virtue of which it offers resistance for the movement of one layer over the other and it is because of Cohesion i.e.attraction between the two layers.

If the attraction between the two layers increases, resistance increases and thereby the viscosity also increases.

 

8Q.What is Newtonian fluid?

Ans: The fluid which follows Newtonian equation is called as the Newtonian fluid and which does not follow is called non-newtonian fluid.

Newtonian Equation(τ) = µ(du/dy) = µ(dv/dy)

 

9Q.What is surface tension?

Ans: It is the property of the liquid surface film to exert tension. It is the force required to maintain unit length in equilibrium and it is represented by σ.

 

10Q.What is pressure?

Ans: it is defined as the ratio of force acting on a body to its unit mass. It is denoted by ‘P

Note:

  • Pressure acting on Water droplet  = 4σ/d
  • Pressure acting on Soap Bubble   = 8σ/d
  • Pressure acting on a liquid jet       = 2σ/d

 

11Q.What is capillarity?

Ans: The rise or fall of fluid in a capillary tube is due to the molecular forces of attraction among the molecules and the glass wall is called as capillarity action.

 

12Q.What are the different types of non-newtonian fluids?

Ans. The different types of non-newtonian fluids are

1.Pseudoplastic

Ex.Milk, blood, paper pulp solution, liquid cement etc.

2.Bingham plastic

Ex.Drilling mud, sewage sludge, toothpaste etc.

3.Thixotropic Fluids

For these fluids, viscosity increases with an increase in time hence they will be called shear thickening fluids.

4.Rheophatic fluids

For these Fluids, the viscosity decreases with the lapse of time.

 

13Q.What is Steady flow?

Ans: If all the properties do not change with respect to time then the flow is said to be a steady flow.

I.e.  ∂P/∂t = 0.

 

14Q.What is unsteady flow?

Ans: If, even a single parameter changes with respect to time then the flow becomes an unsteady flow.

I.e.  ∂P/∂t 0.

 

15Q.What is Rotational or Irrotational flow?

If the fluid particles rotate about their mass center while moving forward the flow is said to be a rotational flow otherwise it is irrotational flow.

 

16Q.What is the Path line?

Ans. It is a line traced by a single particle over its entire journey is called as path line.

Ex. Observing only one particle direction throughout the flow.

 

17Q.What is the streak line?

Ans. The instantaneous picture of the position of all the particles at any instant of time is called as streak line.

Ex.Rocket Propulsion,cigarette smoke etc.

 

18Q.What is the continuity equation?

Ans: It depends upon conservation of mass and it is defined as the mass flow rate at entering of the cross section is equal to the mass flow rate at the exit.

Continuity equation: A1V1 = A2V2

 

19Q.What is Vorticity?

Ans: It is defined as the ratio of Circulation to Area of Cross section.

Vorticity = Circulation / Area

As,Circulation = 2*Wz*Area

Therefore,Vorticity =[ 2*Wz*Area]/Area

       Vorticity = 2*Wz

 

20Q.What is the Potential Function?

Ans: It is a function of space and time defined such that negative derivative with respect to any direction will give the component of velocity in that direction. It is represented as Φ.

-[ ∂Φ/∂x]=u ;  -[ ∂Φ/∂y]=v ;  -[ ∂Φ/∂z]=w

The negative sign indicates that the flow is always in the direction of decreasing potential.

 

21Q.What is the Stream Function?

Ans. It is a function of space and the time defined such that the derivative with respect to any direction will give the component of velocity at right angles in Counterclockwise direction. It is denoted by φ.

 [ φ/∂x]=v ;  [ φ/∂y]=-u

 

22Q. What are the instruments used to measure the discharge, velocity, specific gravity and humidity?

Ans.

  • Venturi meter, Rotometer, and Orifice meter were used to measure the Flow rate or discharge.
  • Pitot tube and the Current meter is used to measure the velocity of the flowing liquid.
  • Hotwire Anemometer is used to measure the turbulent velocity fluctuations in the fluid.
  • The hydrometer is used to measure the specific gravity.
  • A hygrometer is used to measure the humidity.

 

23Q.What is the hammering effect?

Ans. During valve closure, the momentum of flowing fluid will get disturbed and a pressure wave will generate and travels in an opposite direction with acoustic speed(C) with an audible sound(knocking)by hitting the walls called as Hammering effect.

 

24Q.What is the Archimedes principle?

Ans. Whenever an object was immersed either completely or partially, it will be lifted up by a buoyant force(FB)whose magnitude will be equal to the weight of the fluid displaced by the body called as Archimedes principle.

The FB acts vertically upward through the center of buoyancy. The center of buoyancy is a center of gravity for displaced volume.

T = FB -W

 

25Q.What is the boundary layer zone?

Ans.Whenever a real fluid flow over a solid boundary and because of no slip condition, the fluid particle will get stick to the boundary. Hence the velocity of a particle will be equal to the velocity of a boundary.

If the object is at rest, the fluid particle velocity near the boundary will be zero and it is the Greater distance in a normal direction. The fluid particle velocity keeps on increasing and reaches a maximum value at a distance of  ∂.This zone where velocity gradient exists is the boundary layer zone .

 

26Q.What is Bernoulli’s equation?

Ans.Bernoulli’s equation is based on the law of conservation of energy. It is defined as the sum of Potential energy head, Pressure energy head and Kinetic velocity energy head is constant when the liquid is flowing from  one end to another end in a tube or pipe.

 

              Z + (P/ρg ) + V2/2g = Constant

Here,

ZPotential energy head

P/ρg – Pressure energy head

V2/2g – Kinetic velocity energy head

 

27Q.What is Total Energy Line?

Ans. It is a line representing total available energy excluding losses is the total energy line.

Total Energy Line = (Z + (P/ρg ) + V2/2g)

The total energy line will be horizontal for ideal flow and for real fluid it always slopes downwards.

 

28Q.What is Hydraulic Gradient Line?

Ans. It is a line representing total available Piezometric energy. Hydraulic gradient line may raise or fall in the direction of flow.

Z + (P/ρg ) —> Piezometric line

 

29Q.What is Velocity head?

Ans. It is the difference of Total energy line and Hydraulic gradient line.

Velocity head = Total energy line ~ Hydraulic gradient line

  V2/2g             = (Z + (P/ρg ) + V2/2g) ~ (Z + (P/ρg )

 

30Q.What is syphon flow?

Ans.The pressure at the Summit will be minimum and that should not fall below vapour pressure to avoid Cavitation.

 

31Q.What is displacement thickness?

Ans. It is the distance by which the boundary has to be shifted in order to compensate the loss in flow rate on account of boundary layer formation is called as displacement thickness and it is represented as 𝛿*.

 

32Q.What is Momentum thickness?

Ans. Momentum thickness is lost in the momentum and it is represented by “ϴ

 

33Q.What is Energy thickness?

Ans. energy is to compensate the loss in energy And it is presented by 𝛿E

 

34Q.What are the different types of flows in a circular pipe, parallel plate, open channel and Over a sphere(through soil/earth)?

Ans. The different types of flow through pipes are

  • laminar flow
  • Transitional flow and
  • Turbulent flow.

 

Circular Pipe:

  • If the Reynolds number is less than 2000 then it is called as laminar flow. (Re <2000)
  • If the Reynolds number is in between 2000 and 4000 then it is called as transitional flow.(2000<Re<4000)
  • If the Reynolds number is greater than 4000 then it is Turbulent flow. (Re >4000)

 

Parallel Plate:

  • If the Reynolds number is less than 1000 then it is called as laminar flow. (Re <1000)
  • If the Reynolds number is in between 1000 and 2000 then it is called as transitional flow.(1000<Re<2000)
  • If the Reynolds number is greater than 2000 then it is Turbulent flow. (Re >2000)

 

Open Channel:

  • If the Reynolds number is less than 500 then it is called as laminar flow. (Re <500)
  • If the Reynolds number is in between 500 and 1000 then it is called as transitional flow.(500<Re<1000)
  • If the Reynolds number is greater than 1000 then it is Turbulent flow. (Re >1000)

 

Over a Sphere through(Soil/Earth):

  • If the Reynolds number is less than 1 then it is called as laminar flow. (Re <1)
  • If the Reynolds number is in between 1 and 2 then it is called as transitional flow. (1<Re<2)
  • If the Reynolds number is greater than 2 then it is Turbulent flow. (Re >2)

This is the complete explanation of 34 Fundamentals of Fluid Mechanics and hydraulic machinery. If the article is good so please comment us with a positive response.

 

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