[GATE NOTES] Fluid Mechanics - GATE, IES, Govt Exams - Handwritten Notes

FLUID MECHANICS

GATE – IES – GOVT EXAMS – HANDWRITTEN NOTES

ACE ACADEMY TRAINING NOTES

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ABOUT THE BOOK

TITLE : FLUID MECHANICS – GATE/IES/OTHER GOVT EXAMS HANDWRITTEN MATERIAL

SUBJECT : FLUID MECHANICS

IDEAL FOR : GATE,IES, PSU’S – CIVIL ENGINEERING, TSPSC AE/AEE, OTHER CIVIL ENGINEERING GOVERNMENT SECTOR EXAMS.

CONTENTS : ALL THE TOPICS UNDER GATE/IES FLUID MECHANICS SYLLABUS

INTRODUCTION :

Matter can be divided into Solid Liquid and Gas. Liquid and Gases both are fluids. Fluid Mechanics can be further divided into Fluid statics and Fluid Dynamics.

A matter can exist either in solid, liquid or gaseous state. The liquid and the gaseous state together is called fluid state. The solid state and the fluid state together exhibit different characteristics because of differences in the arrangements of molecular structures.

In a given volume, a solid comprises large number of molecules and the attraction between the molecules is very large. Therefore a solid possess a rigid and compact shape and it has a definite volume.

In the same given volume, a liquid contains relatively less number of molecules and the cohesive forces between the molecules is small and therefore in the liquid mass, the molecules will be in motion and a liquid occupies the shape of the container in which is is contained.

For the same given volume, a gas contains much less number of molecules and the attractive forces between the molecules is very small and therefore the gas molecules are in continuous random motion and it occupies the total volume if the container in which it is placed.

Vapour pressure : Consider a closed container in which a liquid is filled by leaving an empty space above the liquid surface.

If the temperate is increased, the vapour bubbles will start forming random leaves from the liquid surface and get collected in empty space. The stage reach where the rate of formation if the new vapor bubbles will be equal to the rate of collapsing of vapor bubbles into the liquid surface. Under this condition, the vapour phase is said to be in phase equilibrium with the liquid. The pressure exerted by the vapour upon the liquid surface is called Vapour Pressure. The partial pressure of water vapour is less than the vapour pressure then no water is present in the late.

If the partial pressure of water vapour is less than the vapor pressure, then no water is present in the lake.
If the partial pressure of water vapour is equal to the vapour pressure then water is present in the lake.
If any fluid flow problems, at any section the pressure should not fall less than or equal to vapour pressure to avoid cavitation.

Manometers are the devices used to measure the pressure at any point in the pipe by balancing the column of the fluid by the different kind of the fluid.

Simple manometers are the devices which contains a narrow tube whose one end is connected to the point where the pressure is to be measured and the other end is open to the atmosphere.