Cristina and John, May 2010
Home in Vienna
Contact
EMail
JohnDFenton@gmail.com
Home address
StUlrichsPlatz 2/4
1070 Vienna
Austria
Phones:
Home +43 1 522 7467
Mobile/Handy/Cellulare:
John +43 664 7313 1035
Cristina +43 650 762 2417
Family History
John's mother spent many years researching the Family History


A method for approximating, smoothing, differentiating,
interpolating, or calculating an envelope to data
While working on river rating curves I developed a
program using quadratic or cubic splines. Its primary use
was to approximate noisy data, but the method seems quite
flexible to approximate moreorless scattered data, or to
smooth, differentiate, interpolate, or calculate an
envelope to that data. An example is Nikuradse's
results for resistance in pipes, which shows variable
curvature:
The program
and a supporting theoretical document are described
here.
Collected papers
Recent publications
 Darvishi, E., Fenton, J. D. and Kouchakzadeh, S.
(2017) Boussinesq equations for flows over steep slopes
and structures, Journal of Hydraulic Research 55(3), 324337. Offprints
available
A finiteslope Boussinesq equation is developed to model
curved transcritical flow over spillways and
broadcrested weirs, even with large slopes. A number of
laboratory experiments were performed with different
transcritical flow problems including changes in channel
gradients and a trapezoidal weir. The equation and the
numerical model were tested using results from those
experiments and from those for a steep and
sharplycurved weir structure, with good results. They
can be used as a computational flume to determine the
headdischarge characteristics of proposed structures. A
novel feature of the equation and numerical method is
that higher derivatives of the bed topography are best
ignored, apparently mimicking the effects of flow
separation in smoothing it.
 Fenton, J. D. (2016) Hydraulics: science, knowledge,
and culture, Journal of Hydraulic Research 54(5),
485501. Offprints
available
The processes of thinking, research, dissemination,
and use of research and knowledge in hydraulics are
examined, differentiating it from hydrology, and
suggesting greater use of scientific methods and
theories. At highly technical levels, that is already
done, but it is suggested that there is room for a
greater simplicity of approach, based on scientific
rigour, recognising that much of what is done in
hydraulics is modelling. This would make understanding,
access to, and participation in research easier for
members of the profession. A number of recommendations
and conclusions are made. The article has a critical
tone, but its main intention is to be helpful to
individual hydraulicians and to the profession at large.
Suggestions are made as to how the profession might use
the Web to give open access to research findings and to
create an open resource for hydraulics knowledge, as
connection by colleagues in all countries is now
possible and feasible.
 Fenton, J. D. and Darvishi, E. (2016) Discussion of
"Minimum specific energy and transcritical flow in
unsteady openchannel flow" by Oscar CastroOrgaz and
Hubert Chanson, Journal of Irrigation and Drainage
Engineering 142(10), http://ascelibrary.org/doi/10.1061/(ASCE)IR.19434774.0001077
We show that there is no justification for the
Singular Point Theory of Massé (1938) for calculating
transitional flows between sub and supercritical
flows.
 Fenton, J. D. (2015) Generating
stream rating information from data, Paper 8,
Alternative Hydraulics.
The problem of using measurements of water level and
discharge to generate stream rating curves is
considered. Current approaches are criticised. Two
methods for the automatic processing of data and
generation of curves are developed, one based on
global polynomials and the other on
piecewisecontinuous approximating splines. Both are
found to work well. They allow the specification of a
weight for each data point, enabling the filtering of
data, possibly incorporating its age, and allowing the
computation of a rating curve for any time in the past
up to the present. It is suggested that ephemeral
changes in bed resistance in some streams may play a
more important role than usually recognised, making
results less certain. For such streams, with scattered
or loopy data, the approximation methods can be used
to generate a rating envelope, allowing the
calculation also of maximum and minimum expected
flows.
 Fenton, J. D. (2015) Basic physical processes in
rivers, Chapter 1 in
Rivers – Physical, Fluvial and Environmental
Processes, (eds) Paweł Rowiński and Artur
RadeckiPawlik, Springer.
The governing long wave equations for a curved
channel can be developed with very few limiting
approximations, especially using momentum rather than
energy. The curvature is then shown to be rarely
important and is subsequently ignored. Wave periods,
imposed by boundary conditions, are asserted to be
fundamental. Long waves have speeds and propagation
properties that depend on period, and there is no such
thing as a single long wave speed. Examination of
dimensionless equations and solution of linearised
equations using wave period shows a novel
interpretation of terms in the momentum equation: the
”kinematic” approximation and wave are misnomers: the
approximation lies not in the neglect of inertial
terms but is actually a very long period one. The
outstanding problem of river modelling, however, is
that of resistance to the flow. A large data set from
streamgaugings is considered and it is shown that the
state of the bed, namely the arrangement of bed grains
by previous flows, is more important than actual grain
size. A formula for resistance is proposed which
contains a parameter representing bed state. As that
state is usually changing with flow, one can not be
sure what the resistance actually will be. This
uncertainty may have important implications for
modelling. The momentum principle is then applied also
to obstacles such as bridge piers, and a simple
approximation gives greater understanding and a
practical method for incorporation in river models.
Finally, river junctions are considered, and the
momentum approach with the very long period
approximation shows that they can be modelled simpl


Lectures in hydraulics, numerics, and maritime
engineering
Introductory page
This is an introduction to
hydraulics. True energy conservation is presented, and
Bernoulli's equation is left to a subsidiary (and
occasionally useful) role. It is an integrated momentum
equation which is valid along a streamline and whose
"constant" varies across streamlines. It is absurd to
expect to apply it in fullyturbulent threedimensional
situations  for example the flow from a reservoir to a
tap in a house. It is much more intellectually honest
simply to use conservation of energy, which is more easily
derived and is a more plausible model of most hydraulic
problems.
A final year elective subject,
dealing with elementary oceanography, water wave theory,
tsunami, and coastal engineering
An introduction to waves and disturbances in channels,
measurement, and structures
An introduction to numerical methods, presenting theory
and applications largely using the optimisation package in
Microsoft Excel.
Coastal and Ocean Engineering  Steady water waves
A computer program ("Fourier") that solves the problem of
steadilyprogressing waves over a flat bottom is described
and made available here: Fourier
Programs that implement Stokes and cnoidal theories are
also available. The instructions file for all is Instructions.pdf.,
which is also included in Fourier.zip. The
latest changes are shown as highlighted comments.
The three wave programs are
 A Fourier approximation method whose only
approximation lies in truncating the number of terms in
the approximating series: Fourier.zip 
current version, 23 July 2015.
 An implementation of cnoidal theory, which is based on
series expansions in shallowness, requiring that the
waves be long relative to the water depth : Cnoidal.zip 
current version, 20 March 2015 (to be unpacked in a
subdirectory of the Fourier one). This is an
approximation, and not as applicable to higher waves as
the Fourier method. It can be used as a check on that
method  for long waves that are not high, both should
give the same results.
 An implementation of Stokes theory, requiring that the
waves be not too long relative to the water depth: Stokes.zip 
current version 20 March 2015 (to be unpacked in a
subdirectory of the Fourier one). This is also an
approximation, and not as applicable to higher waves as
the Fourier method. It can be used as a check on that
method  for waves that are not high or long, both
should give the same results.
