Correct Answer - Option 4 : None of the above
Explanation:
Froude Number:
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The Froude number, Fr, is a dimensionless value that describes different flow regimes of open channel flow.
- The simultaneous motion through two fluids where there is a surface discontinuity.
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Gravity forces and wave-making effect, as with ship’s hulls, Froude number is significant because in those cases gravity forces are predominant and Froude number is the ratio of inertia force and gravity force given by
\({{\rm{F}}_{\rm{r}}} = \sqrt {\frac{{{\rm{Inertia\;force}}}}{{{\rm{Gravity\;force}}}}} = {\rm{\;}}\frac{{\rm{v}}}{{\sqrt {{\rm{gL}}} }}\)
Froude number has the following applications:
- Used in cases of river flows, open-channel flows, spillways, surface wave motion created by boats
- It can be used for flow classification
Use in open channel design i.e free surface flows
Mach number:
Mach number is given by Ma = \(\sqrt {\frac{{{\rm{Inertia\;Force}}}}{{{\rm{Elastic\;Force}}}}} \) = \(\frac{{\rm{V}}}{{\sqrt {\frac{{\rm{K}}}{{\rm{\rho }}}} }}\) = \(\frac{{\rm{V}}}{{\rm{C}}}\)
where V = velocity of an object in the fluid, K = elastic stress and ρ = density of the fluid medium, C = Velocity of sound in the fluid medium
Darcy friction factor:
It is a dimensionless quantity. It is given by-
\({\rm{f}} = \frac{{64}}{{{\rm{Re}}}}{\rm{\;where}},{\rm{\;Re}} = {\rm{Reynold's\;no}}.{\rm{\;}}\)
\(Re ={\rho VD\over \mu}={VD\over \nu}\)
where, ρ = density of fluid, V = velocity of fluid, D = Diameter of pipe,
v = kinematic viscosity
If Re > 4000 then the flow becomes a turbulent flow.
If Re < 2000 then the flow becomes a laminar flow.
