8.1. LABORATORY MEASUREMENTS
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wink of an eye by a computer. However, as Mansard and Funke (1988)
warned:
With the availability of computer-based data acquisition systems
there is a real tendency to let the computer do the thinking. By
having lost the natural editing process that came with the old
strip chart recording technology, it is too easy for data errors to
creep into the data base.
The sage engineer will utilize various methods (visual or otherwise) to inspect acquired measurements to assure quality. In many instances, the
investigator will know what values to expect from the measurements, and
significant departure from the expected range of values is cause for alarm.
Peregrine (1990) gave the classical scientific interactions between theory
and measurement as
a. Observations of a phenomenon in nature or the laboratory
lead to theory being developed to explain it.
b. New phenomena predicted by theory lead to experiments
and/or observations being made to verify the prediction.
c. Discrepancies between theory and measurements stimulate
further development of both.
Peregrine (1990) argued that theory and measurements are complementary rather than in competition, and there needs to be a practical blend of
both in most studies related to waves. One purpose of measurements is to
fill gaps in a theory or between two theories applicable to different regimes.
An example is the transition between laminar and turbulent boundary layers. Measurements can also be used to evaluate approximate theoretical
solutions to determine the range of applicability.
Measuring every hydrodynamic parameter at every location in an experimental study is not feasible. However, values for those unmeasured
quantities can be estimated using theory in combination with measured
values. In cases where no concise theory has been developed, such as in the
case of rubble-mound structure stability, measurements alone provide the
vital means for evaluating the effectiveness of a particular design. Comparing measurements between different design options helps to optimize
the design, and may lead to a better understanding or improvement of the
underlying theory.
8.1.2 Types of Measurements
Each laboratory investigation or physical model study will have its own
measurement requirements based on the purpose of the experiment and on
461
wink of an eye by a computer. However, as Mansard and Funke (1988)
warned:
With the availability of computer-based data acquisition systems
there is a real tendency to let the computer do the thinking. By
having lost the natural editing process that came with the old
strip chart recording technology, it is too easy for data errors to
creep into the data base.
The sage engineer will utilize various methods (visual or otherwise) to inspect acquired measurements to assure quality. In many instances, the
investigator will know what values to expect from the measurements, and
significant departure from the expected range of values is cause for alarm.
Peregrine (1990) gave the classical scientific interactions between theory
and measurement as
a. Observations of a phenomenon in nature or the laboratory
lead to theory being developed to explain it.
b. New phenomena predicted by theory lead to experiments
and/or observations being made to verify the prediction.
c. Discrepancies between theory and measurements stimulate
further development of both.
Peregrine (1990) argued that theory and measurements are complementary rather than in competition, and there needs to be a practical blend of
both in most studies related to waves. One purpose of measurements is to
fill gaps in a theory or between two theories applicable to different regimes.
An example is the transition between laminar and turbulent boundary layers. Measurements can also be used to evaluate approximate theoretical
solutions to determine the range of applicability.
Measuring every hydrodynamic parameter at every location in an experimental study is not feasible. However, values for those unmeasured
quantities can be estimated using theory in combination with measured
values. In cases where no concise theory has been developed, such as in the
case of rubble-mound structure stability, measurements alone provide the
vital means for evaluating the effectiveness of a particular design. Comparing measurements between different design options helps to optimize
the design, and may lead to a better understanding or improvement of the
underlying theory.
8.1.2 Types of Measurements
Each laboratory investigation or physical model study will have its own
measurement requirements based on the purpose of the experiment and on