A traffic flow on a freeway is very dense and it is proposed that possibly a fluid flow could simulate the flow. If it was decided to study the feasibility of the proposal, which flow would Be a possibility? A) An incompressible flow B) A compressible flow with M 1 D) A compressible flow with M = 1

Question

A traffic flow on a freeway is very dense and it is proposed that possibly a fluid flow could simulate the flow. If it was decided to study the feasibility of the proposal, which flow would Be a possibility?
A) An incompressible flow
B) A compressible flow with M < 1
C) A compressible flow with M > 1
D) A compressible flow with M = 1

Quizplus · Accepted Answer

$ \mathrm{M}>1 $
Consider a primary characteristic of an incompressible flow or a subsonic flow: as the area decreases, the velocity increases. For a supersonic flow, as the area decreases the velocity decreases, as demanded by Eq. 9.3.10. We all know that when a traffic flow encounters a decrease in the number of lanes, the traffic slows down, it does not speed up. So, it would require a compressible flow model with $ M>1 $.

A Traffic Flow on a Freeway Is Very Dense and It