Question

Which of the following equations is a result of momentum conservation for inviscid steady flows?

(a) Bernoulli’s equation

(b) Navier-Stokes equation

(c) First law of thermodynamics

(d) Euler’s equation

This question was posed to me by my school teacher while I was bunking the class.

This intriguing question comes from Introduction to Fluid Dynamics in chapter Fluid Dynamics of Fluid Mechanics

Answer 1

The correct choice is (d) Euler’s equation

The explanation: Bernoulli’s equation is an energy conservation equation which is obtained by integration of the Euler equation. Navier-Stokes equation is a force balance equation. The first law of thermodynamics is an energy conservation equation, too. Euler’s equation is a momentum equation. This equation is valid for inviscid steady flows.