Correct Answer - Option 3 : A - d, B - c, C - a, D - b
Explanation:
Compressibility:
Compressibility (C) is a measure of fluid’s relative volume change for when pressure acting on it changes. It is the inverse of Bulk modulus (K) and has units of ‘Pa - 1’.
\({\rm{C\;}} = {\rm{\;}}\frac{1}{{\rm{K}}}{\rm{\;}} = {\rm{\;}}\frac{{\Delta {\rm{V}}/{\rm{V}}}}{{\Delta {\rm{P}}}}\)
It causes a change in the density of the air around an airplane so the aircraft approaches velocity more than the velocity of sound.
Gravity force:
In open channel flow, flow is driven naturally by gravity.
Steady open channel flow are of 4 types:
1. Uniform
2. Gradually varied flow (GVF)
3. Rapidly varied flow (RVF) - Hydraulic jump
4. Spatially varied flow (SVF)
The gravity force is one predominant force in addition to the inertial force. Froude number plays an important role in hydraulic jump and hence gravity has been considered as a significant variable that affects the formation of the hydraulic jump.
Cavitation:
It is the phenomenon of the formation of vapor bubbles of a flowing liquid in a region where the pressure of the liquid falls below the vapour pressure of the fluid and the sudden collapse of these bubbles in the region of higher pressure.
Cavitation starts only when the pressure of the liquid falls below the vapor pressure of that liquid.
Viscosity:
The relative motion between different layers of liquid or gases is opposed by a force, which is known as the Viscous force and this property is known as Viscosity.
The flow of real fluid past a tiny sphere is a flow phenomenon related to viscosity.
∴ The correct answer is option 3: A - d, B - c, C - a, D - b
