9 Experimental Methods in Fluid Mechanics
9.1 Introduction
All previous chapters have clearly illustrated the importance of observations
and experiments for understanding physical processes in the ocean. Although
substantial progress has been made in theoretical and numerical modelling of
many fluid dynamics phenomena, experimental data are still recognized as a
basic source of information. As Mary Nicol Leakey said, theories come and
go, but fundamental data always remain the same. This statement is especially
true for oceanographic data.
Measurements and theory are complementary rather than competitive. Peregrine (1990) listed a few examples of interactions between theory and measurements which are fully applicable for ocean flows, namely: a) observations
in nature or in the laboratory lead to a theory being developed to explain it,
b) new phenomena predicted by theory lead to experiments being made to
verify the prediction, and c) discrepancies between theory and measurements
stimulate further development of both.
In this chapter, we discuss measurement techniques and data processing used
in fluid mechanics. The classical, small scale laboratory experiments have been
described in numerous papers and books (see, for example, Hughes, 1993).
Here we concentrate mostly on the methods and instrumentation used in field
experiments. In particular, in the next section we will provide a brief review
of instruments used for measurement of waves, currents and tides in situ.
The launch of oceanographic satellites has provided a new opportunity to
probe the ocean surface features. Satellite measurements are especially important in the study of the deep oceans, which comprise the vast majority of the
globe, where reliable observations are almost nonexistent. At present, there are
a number of satellite remote sensing systems designed especially for observing
the oceans. Some satellites, carrying instruments specifically for detecting the
ocean surface are described in Sect. 9.3.
One of the first steps in experimental data analysis is to decide which physical variables have an effect on the process being studied and to establish the
functional relationship between all the important variables. The number of
S. R. Massel, Fluid Mechanics for Marine Ecologists
© Springer-Verlag Berlin Heidelberg 1999
9.1 Introduction
All previous chapters have clearly illustrated the importance of observations
and experiments for understanding physical processes in the ocean. Although
substantial progress has been made in theoretical and numerical modelling of
many fluid dynamics phenomena, experimental data are still recognized as a
basic source of information. As Mary Nicol Leakey said, theories come and
go, but fundamental data always remain the same. This statement is especially
true for oceanographic data.
Measurements and theory are complementary rather than competitive. Peregrine (1990) listed a few examples of interactions between theory and measurements which are fully applicable for ocean flows, namely: a) observations
in nature or in the laboratory lead to a theory being developed to explain it,
b) new phenomena predicted by theory lead to experiments being made to
verify the prediction, and c) discrepancies between theory and measurements
stimulate further development of both.
In this chapter, we discuss measurement techniques and data processing used
in fluid mechanics. The classical, small scale laboratory experiments have been
described in numerous papers and books (see, for example, Hughes, 1993).
Here we concentrate mostly on the methods and instrumentation used in field
experiments. In particular, in the next section we will provide a brief review
of instruments used for measurement of waves, currents and tides in situ.
The launch of oceanographic satellites has provided a new opportunity to
probe the ocean surface features. Satellite measurements are especially important in the study of the deep oceans, which comprise the vast majority of the
globe, where reliable observations are almost nonexistent. At present, there are
a number of satellite remote sensing systems designed especially for observing
the oceans. Some satellites, carrying instruments specifically for detecting the
ocean surface are described in Sect. 9.3.
One of the first steps in experimental data analysis is to decide which physical variables have an effect on the process being studied and to establish the
functional relationship between all the important variables. The number of
S. R. Massel, Fluid Mechanics for Marine Ecologists
© Springer-Verlag Berlin Heidelberg 1999