Question

In which of these flows is the kinetic energy important?

(a) Compressible flows

(b) Compressible isothermal flows

(c) Incompressible isothermal flows

(d) Incompressible flows

This question was posed to me in an interview for job.

This intriguing question comes from Incompressible Flows in division Incompressible Flows & Compressible Flows of Computational Fluid Dynamics

Answer 1

Correct answer is (c) Incompressible isothermal flows

Explanation: When the flow is not isothermal, thermal energies play an important role in energy conservation. When the flow is compressible, internal energies play an important role. Only when the flow is incompressible and isothermal, kinetic energies become significant.