Fluid Mechanics

 Do You Know?

👉          Device                               Measurement

            Venturimeter                           rate of flow

             Flow nozzle                           rate of flow

             Orifice meter                          rate of flow

             Bend meter                             rate of flow

             Rotameter                               rate of flow

               Pitot tube                               Velocity of flow

         Hot wire anemometer                 Air & Gas velocity

         Current meter                             Velocity in open channel

👉Classification of Jump

Hydraulic Jump (HJ):  Hydraulic jump is an example of steady rapidly varied flow(RVF)

Hydraulic jump occurs when a supercritical stream meets a Subcritical stream of sufficient depth.

👉Classification of jump 

     Type                     Initial Froude Number (F1)                 EL/E1 (%)

Undular Jump                           1-1.7                                               0

Weak Jump                             1.7-2.5                                            5 -18

Oscillating jump                     2.5-4.5                                            18-45

Steady jump                              4.5-9                                             45-70

Strong Choppy                          > 9.0                                               > 70

Foundation Engineering

 👉 The Primary objective of soil exploration is:

• Determination of the nature of the deposits of soil, depth and thickness of various soil strata.
• Location of Ground water table and obtaining soil and rock samples from the various strata.
•  The determination of the engineering properties of the soil and rock strata that affect the performance of the structure.
• Determination of the in-situ properties by performing field

Methods: Test Pits

                 Boring

                 Standard Penetration Test (SPT) [N Value]

                Cone Penetration Test (CPT): Static cone penetration test (SCPT)[qc value]

                 Dynamic cone penetration test (DCPT)

                 Pressuremeter Test (PMT)

                 Dilatometer Test (DMT)

                 Vane Shear Test (VST)

                Geophysical Exploration: Seismic reflection survey

                                                         Seismic refraction survey

                                                         Seismic Cross-hole survey

                                                         Resistivity Survey

              Plate Load Test

              Pile Load Test

  

👉 Standard Penetration Test (SPT): IS 2131-1981

• The Standard Penetration Test (SPT) is widely used to determine the parameters of the soil in-situ. The test consists of driving a split-spoon sampler into the soil through a bore hole at the desired depth.
•  The split-spoon sampler is driven into the soil a distance of 450 mm at the bottom of the boring
• A hammer of 63.5 kg weight with a free fall of 750 mm is used to drive the sampler.
• The number of blows for a penetration of last 300 mm is designated as the “Standard Penetration Value” or “Number” N.
• The test is usually performed in three stages. The blow count is found for every 150 mm penetration.
• The blows for the first 150 mm are ignored as those required for the seating drive.

• Number of blows for the first 150 mm penetration is disregarded due to the disturbance likely to exist at the bottom of the drill hole
• The test can be conducted at every 1m vertical intervals (Not more than 1.5 m)

👉The refusal of test when

• 50 blows are required for any 150 mm increment.

• 100 blows are obtained for required 300 mm penetration.

• 10 successive blows produce no advance.

👉Two corrections due to:

(a) Overburden pressure (granular soil)

(b) Dilatancy (for saturated fine sands and silts)

👉The corrected N value is given by (overburden correction)

                  

                                   N′ = (CF). N

                 where N′ = corrected value of observed N

                CF = correction factor for overburden pressure

👉Dilatancy Correction

                         

                            N′′= 15+0.5(N′-15)       if N′ > 15

Cone Penetration Test (CPT)

There are two types of CPT

(i) Dynamic cone penetration test (DCPT)                 (ii) Static cone penetration test (SCPT)

Static Cone Penetration Test

• The Static cone penetration test, which is also known as Dutch Cone test, has been standardized by “IS: 4968 (Part-III)-1976 - Method for subsurface sounding for soils - Part III Static cone penetration test”.

• The equipment consists of a steel cone, a friction jacket, sounding rod, mantle tube, a driving mechanism and measuring equipment.

• The cone have an apex angle of 60° ± 15′ and overall base diameter of 35.7 mm giving a cross-sectional area of 10 cm2.

• The friction sleeve should have an area of 150 cm2 as per standard practice.
• The sounding rod is a steel rod of 15 mm diameter which can be extended with additional rods of 1 m each in length.
• The driving mechanism should have a capacity of 20 to 30 kN for manually operated equipment and 100 kN for the mechanically operated equipment.

Dynamic Cone Penetration Test

• The dynamic cone penetration test is standardised by “IS: 4968 (Part I) – 1976 - Method for Subsurface Sounding for Soils-Part I Dynamic method using 50 mm cone without bentonite slurry”.

• The equipment consists of a cone, driving rods, driving head, hoisting equipment and a hammer.

• The hammer used for driving the cone shall be of mild steel or cast-iron with a base of mild steel and the weight of the hammer shall be 640 N (65 kg).

• The cone shall be driven into the soil by allowing the hammer to fall freely through 750 mm each time.

• The number of blows for every 100 mm penetration of the cone shall be recorded.

• The process shall be repeated till the cone is driven to the required depth.

UNION PUBLIC SERVICE COMMISSION (UPSC) PROGRAMME OF EXAMINATIONS/RECRUITMENT TESTS (RTs) -2022

 

UPSC Examinations 2021

 

Target ESE 2022 (Basics of Material Science & Engineering)

 👉Atoms are made of electron, proton and neutrons. 

👉 Electrons and protons are negative and positive charged particles respectively. The magnitude of each charged particle in an atom is 1.6 x 10^-19 Coulombs.

👉The mass of electron is negligible as compare to proton and neutron.

👉The unit of mass is an atomic mass unit

          1 a.m.u = 1.66 x 10^-27 kg 

👉Matter is composed of tiny particles called atoms.

   1. Stable particles: Electron, proton and neutron

   2. Unstable particles- positron, neutrino, anti-neutrino and meson

   3. Composite particles- Deuteron and alpha- particles

👉Electron: It carries a very small negative electrical charge.

                      It has negligible mass i.e. its mass is 1/850th of the mass of hydrogen atom.

👉Proton: It carries small positive electrical charge. 

                   Mass of each proton is same as that of hydrogen atom.

                   Protons are also present in all all the atoms.

 👉Neutron: It does not carry any electrical charge. Its mass is equivalent to that of proton.

👉 Positron or positive electron: The positron or antielectron is the antiparticle or the antimatter counterpart of the electron. The positron has an electric charge of +1 e

👉Meson: The mass of meson is in between the mass of electron and proton.

                   Mesons were discovered during cosmic ray studies.

👉 There are two types of meson (i) p-meson which is heavier (ii) m-meson which is light

👉Both type of mesons may be either negatively or positively charged.

👉Deuteron: It is positively charged.

                      It is heavy hydrogen nucleus.

 👉 Alpha Particles: They are double charged helium nucleus.

                                    They appear as product of radioactive decay.

👉Meson carries a either negative or positive charged.

👉The weight of an electron is 1/1836 of the weight of proton or neutron.

👉Avogadro Number(N) = 6.023 x 10^23

👉Mean distance between atoms in the range of 0.23 nm.

                                                                    Happy Learning

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Target ESE 2022 ( Basics of Energy and Environment)

👉 Ecology: Study of ecosystem. 

👉Ecosystem: It was coined by A.G Tansley

👉Environment: Everything that surrounds or affects an organism during its life time is collectively known as its environment. It comprises both living (biotic) and non-living (abiotic) components.

👉Components of Environment  

             Abiotic (Non-living)                                     Biotic (Living)

               Energy                                                          Green plants

              Radiation                                                      Non-green plants

          Temperature & heat flow                                 Decomposers

                Water                                                             Animals

                 Soil                                                                  Man

👉When an ecosystem is healthy (i.e. sustainable) it means that all the elements live in balance and are capable of reproducing themselves. Ecosystem can be as small as a single tree or as large as entire forest.

👉Types of ecosystem

        (i) Natural                        (ii) Artificial (e.g.  Zoo, aquarium, gardens)

👉 Natural ecosystem can be classified as

       (a) Terrestrial (e.g. Forests, Grasslands, deserts)      (b) Aquatic (e.g.  Lakes, Rivers, Oceans, Ponds)

👉Ecotone: Transition zone between two different zones of ecosystem.(Ecotone is a zone of junction between two or more diverse ecosystems)

e.g. Mangrove forests represent an ecotone between marine and terrestrial ecosystem

 

👉In the Ecotone region , population densities of certain species is greater than adjoining regions. This phenomenon is called Edge Effect.

e.g. Coastal region, wetlands

👉 Characteristics of Ecotone

• It may be very narrow or quite wide
• It has the conditions intermediate to the adjacent ecosystems. Hence it is a zone of tension
• It is linear
• A well developed ecotones contain some organisms which are entirely different from that of the adjoining communities. 

             

                          

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