Mechanical Engineering - Hydraulics and Fluid Mechanics - Discussion

What is bulk modulus?

In simple way bulk modulus define the strength of any material against compression.

When compression done on any material,

Thus it will posses a energy those compressed energy is known as bulk modulus.

The ratio of the compressive or tensile force applied to a substance per unit surface area to change in volume of the substance per unit volume.

Mach number is the ratio of the square of inertia force to the pressure force.

What is meant by inertia force?

A force require to keep the fluid at that velocity (moving velocity) or force require to completely stop the fluid.

In dimensional analysis we use dimensional numbers to check model similarity. In some physical situation elastic force become predominate like inertia force. Mach great scientist introduce a number, which is square root of ratio of inertia and elastic forces to determine similarity between model and prototype.

Here elastic force is product of bulk modulus and area. Thus we need k to determine mach number. And also inverse of mach no is cauchy's no, hence it also need value of k.

Mach Number (M).
M<1 = subsonic flow.
M=1 = sonic flow.
M is 1 to 6 = supersonic flow.
M more than 6 = hypersonic flow.

Mach Number Or Cauchy's Number = Inertia force to elastic force.
Euler number = Inertia force to Pressure force.
Weber's Number = inertia force to surface tension force.
Froude's number = inertia to gravity force.
Reynold's number = inertia to viscous.

Reciprocal bulk modulus of elasticity is compressibility.

Mach number is inertia force/elastic. For bulk modulus machine no require.