Question

Under which condition does the inviscid steady flow become elliptic?

(a) M=1

(b) M<1

(c) M>1

(d) M>5

Answer 1

Right option is (b) M<1

To explain I would say: An inviscid steady flow is elliptic when the flow is subsonic. When the flow becomes supersonic, it changes its behaviour. Hence, it comes under the elliptic category when M<1.