Correct Answer - Option 4 : P-Y; Q-X; R-Z; S-U; T-V
Concept:
\({\rm{Mach\;Number}} = \frac{{Inertia\;force}}{{elastic\;force}} = \frac{{Inertia\;force}}{{Compressible\;force}}\)
Incompressible flow
- M < 0.3
- From the above point, it is clear that the compressibility effect can be treated as negligible when the Mach number is up to 0.2
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Subsonic flow
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0.3 < M < 1
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Sonic flow
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M = 1
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Supersonic flow
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1 < M < 5
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Hypersonic flow
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M > 5
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Froude number
Froude number is the ratio of inertial force to the gravitation force.
\(\text{Froude }{ number}=\text{ }\!\!~\!\!\text{ }{\frac{\text{Inertia force }\!\!~\!\!\text{ }}{\text{Gravitational force }\!\!~\!\!\text{ }}}\)
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
Skin friction coefficient
Skin friction drag is a component of profile drag that occurs differently depending on the type of flow over the lifting body
The local Skin friction coefficient for the boundary layer over a flat plate is given as
\({C_{fx}} = \frac{{0.664}}{{\sqrt {R{e_x}} }}\)
Reynolds number
Reynolds number is a dimensionless formula that is used to differentiate laminar flow from the turbulent flow.
Reynolds number is given by \(Re = \frac{{\rho \times V \times D}}{\mu }\)
In the case of pipe flow,
- If Re ≤ 2000 then flow is laminar
- 2000 ≤ Re ≤ 4000 then flow is transitional
- Re ≥ 4000 then flow is turbulent
Nusselt number
It is the ratio of heat flow rate by convection process to the heat flow rate by the conduction process.
\(Nu = \frac{{{Q_{conv}}}}{{{Q_{cond}}}} = \frac{{hA{\rm{\Delta }}T}}{{\frac{{kA{\rm{\Delta }}T}}{L}}} = \frac{{hL}}{k}\)
