Skin friction:The friction between liquid surface and solid surface is called skin friction. Skin friction occurs from the interaction amid the fluid and the skin of the body, and is directly associated to the wetted surface, Form friction:Friction between the layer is called form friction, form friction arises due to eddies, swirls when flow is turbulent is called form friction Laminar flow:Stream line or steady flow is called laminar flow when a layer does not intermix with each other. Reynolds number for laminar flow is less than 2000 Turbulent flow:Unsteady and non stream line flow is called turbulent flow, when layers intermix with each other due to formation of eddies and vortex .Reynolds number for turbulent flow is greater than 4000. Transition flow:The flow between laminar and turbulent flow is called transition flow, Reynolds number for transition flow is between 2000-4000. Head:Energy per unit weight is called head its unit are lengthE.g. Pressure head, kinetic head, potential head Hydrostatic head:Height of liquid is called hydrostatic head its units also length. It is very important in chemical industries if we know the head we can know the pressure of liquid. Energy head:Energy per unit weight is called energy head, like kinetic energy potential energy etc Dimensionless number:Dimensionless no. is a number which represent property of physical systemLike Reynolds no, Grashoffs no., mach no etcReynolds no: inertial force/viscous forceMach no: velocity of fluid/velocity of soundGrashof no: Buoyancy force/Viscous forcePryndotls no: molecular diffusivity of momentum/molecular diffusivity of Heat Classification of fluids:1) Compressible & non compressible fluids2) Ideal & non ideal fluids3)Newtonian & non Newtonian fluids Compressible fluids:If the volume of fluid varies with temperature and pressure these fluid called compressible fluids, water, milk air etc Non-compressible fluids:If the volume is independent on pressure and temperature is called non-compressible fluids, all ideal fluids are non-compressible fluid they actually does not exist. Ideal fluids:Ideal fluid is a fluid having no viscosity, and incompressible. Ideal fluid do not actually exist ,but some time it is useful to consider what would happened to an ideal fluid in a particular fluid flow problem in order to simplify the problem. Non-ideal fluids:Non-ideal fluids having some viscosity and produce resistance when flow. all fluids are non- ideal fluids Newtonian fluids: Fluids which obey Newtons law of viscosity are as Newtonian . Those fluids in which shear stress (F/A) is directly proportional to the shear rate (dv/dx) are called fluids. Fluids that have constant viscosity at all shear rates at a constant temperature andpressure. Air water oil etc are examples Non-Newtonian fluids: Those fluids which dont obey Newtons law of viscosity. In those fluids relation between shear stress and strain rate is nonlinear and time dependent. Constant coefficient of viscosity cant be defined. Blood,plastic,chocolate,paints are common examples Non Newtonian fluids are further divided in following types. Dilatants (sand) Bingham fluids(toothpaste) Pseudo plastics(blood, paint) Equation of continuity:The product of velocity and area remain constant and is equal to flow rate A1V1=A2V2 Bernoullis equation:The sum of pressure head kinetic head and potential head is equal to constant.It is most important equation of fluid mechanics according to this equation when pressure is high velocity will be low and vice versa Pressure drop:It is drop in pressure between two ends of point due to friction and other losses. Pressure difference:It is difference in pressure between two ends of pipe; pressure may be increase or decrease. Baffles:These are strips of metal or other material to change the flow mainly produces turbulence which increase the rate of mixing Louvers:These are strips which control the flow and change the direction of flow. Swirls:When flowing fluid strike on the walls it produce swirls Wakes:These are waves produce behind the fluid when it moves due to high turbulences Vortex:Intermixing of layers are called vortex. Boundary layers:When fluid flow from the solid surface, due to high friction fluid speed decreases which disturb the whole flow, the portion which is disturbed called boundary layers.It is very important factor in fluid motion when fluid overcome this boundary layer effect fluid can easily flow by applying pressure Rhyology:To study the non-Newtonian fluids fluid and their graph called rhylogyReynolds number for Open and closed channel:Reynolds no. for laminar flow in open channels like canal is 500, and for transition flow is 500-2000 and for turbulent flow is >2000Reynolds no. for closed system laminar up to 2000, transition between 2000-4000 and turbulent >4000Flow meters:Flow meters are devices which are used to measure flow rate by measuring pressure differenceThere are two categorize of flow meters:1) Variable head meter2) Variable area meter Variable head meter: the flow measuring devices which measure flow rate at the expense of change in head like kinetic energy change into pressure energy or pressure energy into kinetic energy while in variable area meter pressure difference measure expense of change in area and pressure difference remain same in variable area meters.Orifice meter:Device used to measure flow rate at the expense of pressure difference called orifice meter

For gases we use smaller orifice as compared to orifice used to liquid because of volume gases much higher than liquid. Those liquids which contain vapors we use weep holes to remove these. Pressure drop is large in case of orifice meter due to formation of vena contracta.Venturi meter:A device having small converging cone and large diverging cone. Converging cone is small because we want rapid pressure drop and diverging cone is large because to minimize pressure drop and minimize pressure lost.

Venture meter is also used to measure flow rate of gases it is very efficient meter having large co-efficient of discharge with minimum power loses.When venture meter vertically installed head involved in it.Tapings are installed on throat and converging cone Rota meter:It is variable head meter. It is normally installed vertically made by tapered tube. Efficiency of Rota meter depends on type of float when rot meter installed horizontally head will not involved.

Discharge coefficient depend on shape of Rota meter curved shape float have maximum flow rate depend on the annular space. In the case of liquid when buoyancy force is equal to gravitational force this is equal to pressure. In the case of gases buoyancy force is negligible then pressure equals to gravitational force.Pitot tube:Pitot tube is a device used to measure point velocity having two holes one for static pressure other for impact pressure