Question

In the mass flow rate correction term at low Mach numbers, which of these terms dominate?

(a) The density correction

(b) The gradient of density correction

(c) The pressure correction

(d) The gradient of pressure correction

I have been asked this question during an online exam.

My doubt stems from Compressible Flows in section Incompressible Flows & Compressible Flows of Computational Fluid Dynamics

Answer 1

Right answer is (d) The gradient of pressure correction

Explanation: There are two terms involved in the mass flow rate correction. When the Mach number is low, the gradient of pressure correction term dominates the flow and makes the equation elliptic.