Question

For incompressible flows with no body forces, the volume integral term is ____________

(a) viscous terms

(b) pressure forces

(c) body forces

(d) flux terms

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

My question comes from Incompressible Flows topic in division Incompressible Flows & Compressible Flows of Computational Fluid Dynamics

Answer 1

Correct answer is (a) viscous terms

The explanation is: Pressure forces and body forces are not present as the flow is incompressible and has no body forces. The flux terms are usually treated with the Gauss-Divergence theorem and converted into surface integrals. Therefore, the viscous terms remain as volume integrals here.