Similarity solution for a laminar round jet
= Similarity solution for a laminar round jet
With axisymmetric streamfunction $\psi=\nu z g(r/z)$, the regular normalized similarity profile is
$$
g(\eta)=\frac{12M\eta^2}{32\nu^2+3M\eta^2}.
$$
Its volume flux grows linearly with $z$, expressing <fluid entrainment>.