Reply To: Reference for strain rate tensor prefactor in powerLawBGKdynamics
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pre2 is just a multiplicative constant, which is calculated before for the sake of readability. The code lines quoted by Junwei are the implementation of Eqq. 13-14-15 in Boyd et al. (2006). Differences in multiplicative factors are due to different definitions of shear rate(see Eqq 12 and 14 in the cited article: in our code, the 2 factor is not present), different way of reporting the sound velocity (the cited article directly reports its numerical value sqrt(3), while the code adopts a more general notation), and different ways of treating density (in the cited article, everything is divided by density, which is striped out of the equations in this way, while the code keeps it in the passages).