When Mach number is less than unity, the flow is called-
Sub-sonic flow
Therefore, when the Mach number is less than unity, the flow is called Sub-sonic flow. Mach Number (M) Flow Type Characteristics M < 1 Sub-sonic Speed less than sound; pressure waves move upstream M = 1 Sonic Speed equals sound; critical condition 1 < M < \approx 5 Super-sonic Speed greater than sound; shock waves form M > \approx 5 Hyper-sonic Very high speed; significant heating effects Conclusion Based on the definition and classification of flow regimes by Mach number, a flow with a Mach number less than unity (M < 1) is known as Sub-sonic flow.
Important Questions from Dimensionless Number
Match the following and select the correct answer from the codes given below the lists
List I
List II
A.
Steam Nozzle
1.
Mach number
B.
Compressible flow
2.
Reaction turbine
C.
Surface Tension
3.
Biot number
D.
Heat conduction
4.
Nusselt number
5.
Supersaturation
6.
Weber number
The Reynold’s number, used for critical velocity for turbulent flow of fluids, is given by the relation
Reynolds number for non - circular cross-section is:
[V = mean velocity, ν = kinematic viscosity, P = ratio of cross-sectional area to the wetted perimeter]
A) \(V.\frac{{4P}}{v}\)
B) \(\frac{{V.P}}{v}\)
C) \(\frac{{V.2P}}{{4v}}\)
D) \(\frac{{V.P}}{{4v}}\)
When the Mach number is less than unity, the flow is
The only possible dimensionless group that combines velocity ‘V’, body size ‘L’, fluid density ‘ρ’ & surface tension ‘σ’
