Question

Consider three-dimensional Euler equations. Which equation will you use to find the value \((\frac{\partial u}{\partial t})_{i,j}^t\)?

(a) Energy equation

(b) y-momentum equation

(c) x-momentum equation

(d) Continuity equation

The question was posed to me in a national level competition.

The origin of the question is Finite Difference Methods in chapter Finite Difference Methods of Computational Fluid Dynamics

Answer 1

The correct option is (c) x-momentum equation

Explanation: The x-momentum equation gives the time derivative if the x-component of velocity at a particular time in terms of the other flow variables and their special derivatives. So, this can be used to get the time derivative \((\frac{\partial u}{\partial t})_{i,j}^t\).