Page 27 - 48Fundamentals of Compressible Fluid Mechanics

0.4. VERSION 0.3 xxvii

pressible Flow was chosen, while relatively simple topics like fundamentals of
strength of material were delayed, is because of the realization that manufacture
engineering simply lacks fundamental knowledge in this area and thus produces
faulty designs and understanding of major processes. Unfortunately, the under-
signed observed that many researchers who are dealing with manufacturing pro-
cesses are lack of understanding about fluid mechanics in general but particularly
in relationship to compressible flow. In fact one of the reasons that many manufac-
turing jobs are moving to other countries is because of the lack of understanding
of fluid mechanics in general and compressible in particular. For example, the lack
9
of competitive advantage moves many of the die casting operations to off shore .
It is clear that an understanding of Compressible Flow is very important for areas
10
that traditionally have ignored the knowledge of this topic .
As many instructors can recall from their time as undergraduates, there
were classes during which most students had a period of confusion, and then
later, when the dust settled, almost suddenly things became clear. This situation
is typical also for Compressible Flow classes, especially for external compressible
flow (e.g. flow around a wing, etc.). This book offers a more balanced emphasis
which focuses more on internal compressible flow than the traditional classes. The
internal flow topics seem to be common for the “traditional” students and students
from other fields, e.g., manufacturing engineering.
This book is written in the spirit of my adviser and mentor E.R.G. Eckert.
Who, aside from his research activity, wrote the book that brought a revolution in
the heat transfer field of education. Up to Eckert’s book, the study of heat transfer
was without any dimensional analysis. He wrote his book because he realized that
the dimensional analysis utilized by him and his adviser (for the post doc), Ernst
Schmidt, and their colleagues, must be taught in engineering classes. His book
met strong criticism in which some called to burn his book. Today, however, there
is no known place in world that does not teach according to Eckert’s doctrine. It is
assumed that the same kind of individuals who criticized Eckert’s work will criticize
this work. This criticism will not change the future or the success of the ideas in
this work. As a wise person says “don’t tell me that it is wrong, show me what is
wrong”; this is the only reply. With all the above, it must be emphasized that this
book will not revolutionize the field even though considerable new materials that
have never been published are included. Instead, it will provide a new emphasis
and new angle to Gas Dynamics.
Compressible flow is essentially different from incompressible flow in
mainly two respects: discontinuity (shock wave) and choked flow. The other is-
sues, while important, are not that crucial to the understanding of the unique phe-
nomena of compressible flow. These unique issues of compressible flow are to
be emphasized and shown. Their applicability to real world processes is to be
9 Please read the undersigned’s book “Fundamentals of Die Casting Design,” which demonstrates
how ridiculous design and research can be.
10 The fundamental misunderstanding of choking results in poor models (research) in the area of die
casting, which in turn results in many bankrupt companies and the movement of the die casting industry
to offshore.