In Chaps. 5 and 6, we have focused the attention on situations without net mass flow, i.e. with local barycentric velocity \(\textbf{v}=0\) . Obviously, it is physically important considering situations with net mass flow, which are practically relevant, for instance, in cryogenics situations. Thus, we will give a short introduction to this topic. Furthermore, other forms of turbulence arise for the barycentric velocity higher than some critical value which are analogous to those arising when the heat flux is higher than some critical value.