deletions | additions       diff --git a/Payam.tex b/Payam.tex  index 5ebd69d..6dc1f53 100644  --- a/Payam.tex  +++ b/Payam.tex 
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\item {\it Does Payam assume incompressible flow?} I believe so -- he follows Landau \& Lifshitz in setting up the submerged jet; and I believe they assume zero divergence in the velocity field. (Note that the derivation in \citet{Broman_Rudenko_2010} assumes incompressibility.) This means that the sound speed in his model will be infinite. {\it Would there be any point in re-visiting the derivation with incompressibility assumption dropped?}  \item %\item  (Sound speed shouldn't depend on viscosity at except for near-supersonic flow. (\href{http://iopscience.iop.org/0370-1301/66/5/303/pdf/0370-1301_66_5_303.pdf}{Or does it?} \href{http://www.engineeringtoolbox.com/sound-speed-water-d_598.html}{Speed of sound table}, \href{http://resource.npl.co.uk/acoustics/techguides/soundpurewater/content.html#LUBBERS}{$c(T,P)$ fits}.)) \end{itemize}