Page 839 - Fundamentals of Water Treatment Unit Processes : Physical, Chemical, and Biological

794 Appendix D: Fluid Mechanics—Reviews of Selected Topics

BOX D.1 REMINISCENCES ON PROFESSOR Students who took his course seemed to sweat as they
HUNTER ROUSE did at Iowa; I always advised my students to take the
course, first to have the ‘‘experience’’ of Rouse, and
Professor Hunter Rouse (1906–1996) was one of the
second, because as an environmental engineer, one can-
traditional academics (defined here as those in the gen-
not know too much in the field of fluid mechanics.
erations that preceded the author’s). The author was a
Rouse’s writings were concise, eloquent, insightful,
student in Rouse’s 1961–1962 first-year fluid mechanics
and substantive, i.e., what one should strive to emulate.
graduate course. Rouse followed his book closely, and,
This was true of his spoken word as well, i.e., articulate
consistent with his book, there was little, if any, men-
and always the model of decorum, never flamboyant. As
tion of the Moody diagram. Most probably, this was
a note, the formal style of academics in Rouse’s gener-
because his view was to advance knowledge in terms of
ation was a contrast with the more relaxed approach of
fundamentals rather than by what seemed expedient
the subsequent generation in the United States (but prob-
(consistent with the discussion in the previous para-
ably not in Europe, i.e., from what the author has seen).
graph). He was Director of the Iowa Institute of
A more complete review of Professor Rouse’s contri-
Hydraulic Research (now IIHR-Hydroscience and
butions in teaching, research, and writing was provided
Engineering) at the University of Iowa, known world-
by Professor Robert Ettema (2006) and by Kennedy and
wide as the ‘‘Mecca’’ for attracting engineers and
Macagno (1971). Professor Ettema’s paper (Ettema,
scholars in the field. As to persona, Rouse was always
2006) brought to mind that Rouse was a perfect person
dignified and, to a student, seemed Teutonic. Maybe his
for the ‘‘golden age’’ of hydraulic research, when the
time at Karlsruhe (Technische Hochschule, doctorate in
foundation for the modern state of the art was being
1932) had an influence; but whatever, Rouse seemed a
established, starting with Prandtl, c. 1901, which was
natural German. His lectures were usually one or two
largely in place by the 1960s. A large proportion of the
simple questions that related to the topic of the day as
academics that continued hydraulic research and teach-
described in his book and that confounded most of the
ing in the United States and worldwide, e.g., from per-
students; usually, however, one or two students had the
haps 1940, were from Iowa as were many of the hydraulic
correct approach. The students did most of the talking,
engineers who were doing hydraulic modeling and
usually interspersed with an incisive question by Pro-
designing hydraulic structures. Rouse’s contributions in
fessor Rouse. Sometimes, he introduced a topic or gave
teaching, research, writing, and leadership have influ-
a brief discourse, but seldom a full lecture. He expected
enced our understanding of the modern state of the art
the participation of all of the graduate students, writing
of fluid mechanics and hydraulics.
on a pad the performance of each student during the
The foundation laid at Iowa in experimental hydraulics
session (one could only speculate on what he had writ-
was the basis for a continuation in the form of computer
ten). A student could not do well, however, merely by
modeling, started c. 1960, at IIHR using Fortran and
reading his book. Each of his class sessions was an
mainframe computers and known since the early 1990s
experience. Later, after he retired from Iowa (as Dean
as computational fluid dynamics (CFD). The main task
of Engineering), he came to CSU for the summers to
was to solve the classical Navier–Stokes equation by finite
give a shorter version of his course. Perhaps this was
difference, which opened a new epoch in fluids modeling
due to the influence of Professor Albertson, who was
and, at the same time, became a tool of practice. The
one of Rouse’s doctoral students.
Navier–Stokes relation is a differential equation, intimi-
dating at first glance, but was less so after Rouse’sbrief
explanation, i.e., that the equation was merely Newton’s
second law, F ¼ ma, in an expanded form. This charac-
terized Rouse’s style, which was to reduce a complex
topic to its simple essence.
D.2.1 FLUID SHEAR
The equation for fluid shear in viscous flow is
dv
t ¼ m (D:8)
dy
Hunter Rouse, c. 1960 (from the Archives IIHR—Hydroscience in which
2
and Engineering, University of Iowa; used with permission) t is the shear stress (N=m )
2
m is the dynamic viscosity (N s=m )