Dear Dr. Huang,

I have now heard from the referees regarding your paper, "Aerodynamics
of a Curveball in 2D Navier-Stokes Flow", and copies of their reports
are enclosed.

Given the very critical contents of there reports, I regret to inform
you that I must decline your paper for publication in Physics of Fluids.

Sincerely,

John Kim

Encl: Referee report

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General comments and recommendation re publication:

The author has, potentially, made an important advance in writing an
algorithm for the motion of a circle in a 2D incompressible, viscous
flow. However, the write-up is very sketchy, e.g., the numerical method
for advancing the fluid flow is not even mentioned. Much of what is
written up is obvious and/or well known. The real substance of the
manuscript is on pp.9-12 and this is the vaguest part of the manuscript.
The figure produced is interesting but, at this stage, irreproducible
by others based on the information provided.

I recommend that the author write a full manuscript and explain what he
has done and not try to write a brief but unintelligible letter. As it
stands, the manuscript suggests that the approach is either inconsistent
or not fully thought through. The figure, of course, suggests that the
author has something complete enough to program on a computer. It is
difficult to tell from write-up whether the theory is correct or
complete, and it is impossible to assess the accuracy of the simulation.

It would be premature to publish this in Physics of Fluids.

If the author's method works, all the various "balls" (knuckleball,
fastball, forkball, etc.) should follow from it by variations in the
initial conditions as the ball leaves the pitcher. Of course, they may
not all have counterparts in 2D. However, the text seems to see anything
but a curveball as remaining a mystery.