Types of flow in fluid mechanics

Types of flow in fluid mechanics

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  GOVERNMENT ENGINEERING COLLEGE BHAVNAGAR
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   Subject :Fluid Mechanics  Topic : Types of Flows  Branch : 4th Mechanical  Prepared By :  Amit H. Makwana ( 140210119064 )  Dharmesh D. Baraiya ( 140210119005 )
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  Types of Flows Steady and unsteady flow.  Uniform and non-uniform flow.  Laminar and turbulent flow.  Compressible and incompressible flow.  Rotational and irrotational flow  One, two and three-dimensional flow.
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  Steady and UnsteadyFlow : • The flow in which fluid characteristics like velocity, pressure, density etc. at a point does not changes with time is called as steady flow. • Eg flow of water with constant discharge through a pipeline is as steady flow. ∂v / ∂t = 0 ∂ρ / ∂t = 0 ∂ρ / ∂t = 0 • The flow in which fluid characteristics like velocity, pressure, density etc. at a point changes with time is called as unsteady flow. • E.g flow of water with varying discharge though a pipe is as unsteady flow. ∂v / ∂t ≠ 0 ∂ρ / ∂t ≠ 0 ∂ρ / ∂t ≠ 0
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  Uniform and Non-uniformFlow : • The flow in which velocity at a given time does not change with respect to space (length of direction of flow is called as uniform flow. • E.g flow through a long straight pipe of uniform diameter is considered as uniform flow. ∂v / ∂s = 0 • The flow in which velocity at a given time changes with respect to space (length of direction of flow) is called as non- uniform flow. • E.g flow through a long pipe with varying cross section is consider as non-uniform flow. ∂v / ∂s ≠ 0 (a) Uniform velocity (b) Non – uniform velocity
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  Laminar and TurbulentFlow : • The flow in which the adjacent layer do not cross to each other and move along the well defined path is called as laminar flow. • E.g. flow of blood in small veins, flow of ail in bearings, flow in porous media, flow of highly. • The flow in which the adjacent layers cross each other and do not move along the well define path is called as turbulent flow. • E.g. flow through a river or canal, smoke from chimney, smoke from a cigarette.
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  • If Reynolds’snumber is less than 2000, then the flow is laminar. • If Reynolds’s number is more than 4000, then the flow is turbulent. • If Reynolds’s number is between 2000 to 4000, then the flow is transit.
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  Compressible and IncompressibleFlow : • The flow in which the density does not remain constant for the fluid flow is called as compressible flow. • E.g. problems involving flight of rockets, aircrafts, flow fo air in problems concerned with tubomachines, compressor blades, flow of gases through openings like nozzles. • The flow in which the density is constant for the fluid flow is called as incompressible flow. • E.g. problems involving liquids i.e. hydraulics problems, flow of gases in machines like fans and blowers.
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  Rotational and IrrigationalFlow : • The flow in which the fluid particle while flowing along stream lines, also rotate about their own axis is called as rotational flow. • E.g. motion of liquid in a rotating cylinder (forced vortex) as rotational flow. • The flow in which the fluid particle while flowing along streamlines, do not rotate about their own axis is called as irrigational flow. • E.g. flow of liquid in an emptying wash-basin (free vortex) as a rotational flow.
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  One, Two andThree-dimensional Flow : • The flow in which the velocity is the function of time and one space co-ordinate (x) is called as One-dimensional flow. • E.g. flow through the pipe is consider as a one dimensional flow. u = f(x), v = 0, w = 0 • The flow in which the velocity is the function of time and to space co-ordinate (x,y) is called as two-dimensional flow.
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  • Eg viscousflow between parallel plates of large extent, flow at the middle part of airplane wing, flow over a long spillway, flow below long weirs are consider as two-dimensional flow. u = f1(x,y), v = f2 (x,y), w = 0 • The flow is converging or diverging pipes or open channels are as three dimensional flow. Flow in a river, flow at a inlet of a nozzle etc. are the example of three-dimensional flow. u = f1 (x,y,z), v = f2 (x,y,z), w = f3 (x,y,z) 0