Compressibility and divergence-free flow

[smarras]

Hi there, I'd like to know if, under the conditions of thermal flows (viscous, conductive) and low Mach numbers (< 0.3), it is formally/conceptually correct to affirm that "non-divergence is only necessary condition for incompressibility"

Thank you very much in advance

S.

 

[sayak]

As far as I am aware Div(V)=0 is the only condition for incompressible flows. If Div(V) is not zero, flow is not incompressible and vice versa. So necessary and sufficient.

 

[smarras]

Hi there Sayak, thank you very much for replying!
All the best

Simone