GOVERNMENT ENGINEERING COLLEGE VALSAD SUB : FLUID MECHANICS DEPT. : CIVIL (3rd sem)

GROUP MEMBERS SUBMITTED TO : PROF. KULDEEP PATEL 1.Moxesh shah 130190106053 2.Mayank doshi 130190106025 3.Viral patel 130190106043 4.Hari bhavsar 130190106008 SUBMITTED TO : PROF. KULDEEP PATEL

FLUID

What is Fluid ? A fluid is a substance which deforms continuously under the action of shearing forces , however small they may be .

What is Fluid Mechanics ? Fluid mechanics is the branch of engineering science deals with the study of the fluids at rest as well as in motion . In general the scope of fluid mechanics is very wide which includes the study of all liquids and gases . This branch of engineering science deals with the static , kinematics and dynamic aspects of fluids . Study of fluid at rest is called fluid statics. The study of fluids in motion , where pressure are not considered is called fluid kinematics. The pressure forces are also considered for the fluids in motion is called fluid dynamics.

TOPICS TO LEARN Properties of fluid Viscosity Types of fluids Cohesive and adhesive forces Surface tension Capillarity action Vapour pressure compressibility

PROPERTIES OF FLUID Density or mass density Weight Density or specific weight Specific gravity or Relative density Specific volume

Density or mass density Density or mass density of a fluid is defined as the ratio of the mass of a fluid to its volume . Mass per unit volume of a fluid is called density . It is denoted by Greek letter ρ (rho) . Mathematically , ρ = SI unit of mass density is kg/m3 .

Specific volume It is defined as the volume per unit mass of fluid . It is the reciprocal of mass density . Mathematically , Specific volume v = = Its SI unit is m3/kg

Weight Density or Specific weight It is defined as the ratio of the weight of fluid to its volume . Thus weight per unit volume of a fluid is known as weight density . It is denoted by the symbol w . Mathematically , w = = It SI unit is N/m3

Specific gravity or Relative density It is the ratio of density of a fluid to the density of the standard fluid . For liquids , the standard fluid is taken water and for gases , the standard fluid is taken air . It is denoted by the symbol s . Mathematically , For liquids , s = It is an dimensionless quantity

For gases , s = Thus , density of a fluid = s × Density of water = s × 1000 kg /m3 The specific gravity of water is 1 and for mercury it is 13.6 .

VISCOSITY Viscosity is defined as the property of fluid which offers resistance to the movement of one layer of the fluid over another layer of fluid v = 0 The resistance is due the frictional forces between the layers as the slides passess one over the other As shown in the above fig. Inside a pipe or tube a very thin layer of fluid right near the walls of the tube are motionless because they get caught up in the microscopic ridges of the tube. Layers closer to the center move faster and the middle layer moves the fastest Viscosity can be thought as the internal stickiness of a fluid Different kinds of fluids flow more easily than others. Oil, for example, flows more easily than honey. This is because honey has a higher viscosity, which is a measure of resistance to fluid flow.

VISCOCITY DYNAMIC KINEMATIC (1) dynamic viscosity Consider two parallel plates, placed a small distance Y apart, the space between the plates being filled with the fluid.

The lower surface is assumed to be stationary, while upper one is moved parallel to it with a velocity u by the application of a force f, corresponding to some area a of the moving plates The particles of the fluid in contact with each plate will adhere to it. The velocity gradient will be a straight line. The action is such as if the fluid were made up of a series of thin sheets.