deletions | additions       diff --git a/Payam and DNA.tex b/Payam and DNA.tex  index 0a0c078..0fe74b0 100644  --- a/Payam and DNA.tex  +++ b/Payam and DNA.tex 
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I want to think about {\it which time scale is more appropriate in this context and why?}  \item So, {\it what should the time-scale be from }physical {\it reasoning: what is the physics behind establishing the flow profile $\vec{v}(\vec{x})$ in the fluid around the DNA/jet?}\\  \citet{1959flme.book.....L} argue $\vec{v}(\vec{x})$ purely from momentum conservation / Gauss' Law, and symmetries of the momentum flux tensor. Time plays no role because the source of the momentum is static with respect to the (``Eulerian'') fluid. fluid.\\   {\it  Can we do the same analysis with a {\it moving} submerged jet? jet?}  \item {\it Does Payam assume incompressible fluid?} Yes -- he follows \citet{1959flme.book.....L} pp. 86-88 in setting up the submerged jet; they assume zero divergence in the velocity field \& use stress tensor for incompressible flow. (The derivation in \citet{Broman_Rudenko_2010} also assumes incompressibility.) This means that the sound speed in his model will be infinite, and sonic information transfer will be irrelevant. This is why there is only one possible time-scale in the theory.