Is non-compressibiliy and encompressibility is one thing only
Share
Is non-compressibiliy and encompressibility is one thing only
Sign Up to our social questions and Answers Engine to ask questions, answer people’s questions, and connect with other people.
Login to our social questions & Answers Engine to ask questions answer people’s questions & connect with other people.
The compressibility of a fluid is a measure of the relative volume change in response to a pressure change. It is defined regardless of whether or not this fluid is flowing since it is a thermodynamic characteristic of that fluid.
The compressibility of a fluid is a measure of the relative volume change in response to a pressure change. It is defined regardless of whether or not this fluid is flowing since it is a thermodynamic characteristic of that fluid.On the other hand, the compressibility of a flow is directly related to the value of the Mach number in the flow. One can show that second order taylor decomposition of the momentum equation leads to a term for fluctuating pressure that scales as M2. As a consequence, one can consider that the flow is incompressible as long as the Mach number is lower than 0.3 regardless of the fluid at hand. In the case M=0.3, the "acoustic" fluctuating pressure (which is how is often called this second order term in pressure) correspond to 10% of the convective (or aerodynamic) pressure term. To explore further this link please have a look at the derivation of the Low-Mach Number Navier Stokes equation derivation.