Mechanical Engineering - Hydraulics and Fluid Mechanics - Discussion

Bulk modulus is equal to the reciprocal of compressibility.

And Mach number is depends upon the compressibility.

Thank you all.

Bull modulus is directly proportional to the pressure that why it may be used for determine the eulier number.

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

Bulk modulus is equal to the reciprocal of compressibility.

And Mach number is depends upon the compressibility.

Therefore to determine Mach number bulk modulus is required.

What is mach number?

E = density*dp/change in density. From bernoulli's equation if the order of pressure is same as the order of dynamic pressure then dp=density*velocity square/2. By substituting this in equation for bulk modulus we get. Change in density/density=1/2* (mach. No) square. Where mach number Ma=v/a.

9 velocity of fluid flow/velocity of sound in medium. If change in density/density is < 0. 05 we say fluid is incompressible. So Ma, 0. 33 for the flow to be compressible.

Mach no = inertia force / elastic force . It is a dimensionless quantity also defined as ratio of velocity of the flow / velocity of sound. Velocity of sound = sqrt (y. R.T ) y - gama.

M = v (ρ / E)1/2.

ρ-density;
E - Bulk Modulus of Elasticity.

If the value of mach number is 3, then the flow is called supersonic.