Gas Dynamics

1.3.  HISTORICAL BACKGROUND 3
tic) 7 . Aeronautics is an overlapping part of compressible ?ow, however these two
?elds are different.  For example, the Fanno ?ow and isothermal ?ow, which are
the core of gas dynamics, are not part of aerodynamics. Possible reasons for the
lack of written documentation are one, a large part of this knowledge is relatively
new, and two, for many early contributors this topic was a side issue. In fact, only
one contributor of the three main models of internal compressible ?ow (Isothermal,
Fanno, Rayleigh) was described by any text book.  This was Lord Rayleigh, for
whom the Rayleigh ?ow was named.  The other two models were, to the under-
signed, unknown. Furthermore, this author did not ?nd any reference to isothermal
?ow model earlier to Shapiro’s book. There is no book 8 that describes the history
of these models.  For instance, the question, who was Fanno, and when did he
live, could not be answered by any of the undersigned’s colleagues in University of
Minnesota or elsewhere.
At this stage there are more questions about the history of compressible
?ow needing to be answered. Sometimes, these questions will appear in a section
with a title but without text or with only a little text. Sometimes, they will appear in a
footnote like this 9 . For example, it is obvious that Shapiro published the erroneous
conclusion that all the chocking occurred at M = 1 in his article which contradicts
his isothermal model. Additional example, who was the ?rst to “conclude” the “all”
the chocking occurs at M = 1? Is it Shapiro?
Originally, there was no idea that there are special effects and phenomena
of compressible ?ow. Some researchers even have suggested that compressibility
can be “swallowed” into the ideal ?ow (Euler’s equation’s ?ow is sometimes re-
ferred to as ideal ?ow). Even before Prandtl’s idea of boundary layer appeared, the
signi?cant and importance of compressibility emerged.
In the ?rst half of nineteen century there was little realization that the com-
pressibility is important because there were very little applications (if any) that re-
quired the understanding of this phenomenon.  As there were no motivations to
investigate the shock wave or choked ?ow both were treated as the same, taking
compressible ?ow as if it were incompressible ?ow.
It must be noted that researchers were interested in the speed of sound
even long before applications and knowledge could demand any utilization.  The
research and interest in the speed of sound was a purely academic interest. The
early application in which compressibility has a major effect was with ?re arms. The
technological improvements in ?re arms led to a gun capable of shooting bullets
at speeds approaching to the speed of sound. Thus, researchers were aware that
the speed of sound is some kind of limit.
In the second half of the nineteen century, Mach and Fliegner “stumbled”
over the shock wave and choking, respectively. Mach observed shock and Fliegner
7Anderson, J. D., Jr.  1997.  A History of Aerodynamics: And Its Impact on Flying Machines, Cam-
bridge University Press, Cambridge, England.
8The only remark found about Fanno ?ow that it was taken from the Fanno Master thesis by his
adviser. Here is a challenge: ?nd any book describing the history of the Fanno model.
9Who developed the isothermal model?  The research so far leads to Shapiro.  Perhaps this ?ow
should be named after the Shapiro. Is there any earlier reference to this model?4 CHAPTER 1.  INTRODUCTION
measured the choking but theoretical science did not provide explanation for it (or
was award that there is an explanation for it.).
In the twentieth century the ?ight industry became the pushing force. Un-
derstandably, aerospace engineering played a signi?cant role in the development
of this knowledge. Giants like Prandtl and his students like Van Karman, as well as
others like Shapiro, dominated the ?eld. During that time, the modern basic classes
became “solidi?ed.” Contributions by researchers and educators from other ?elds
were not as dominant and signi?cant, so almost all text books in this ?eld are writ-
ten from an aerodynamic prospective.