2.6.2.4 Optimal Orientat ion
The first step in the simulation is to determine the optimal
orientation of the boom. It is assumed that the optimal
orientation is constant for different boom lengths
and perpendicular to the flow direction in the selected
point. A simple method to approximate the direction of
the flow in a point is illustrated in Figure 2.42.
A circle of radius ‘r’ is defined around a location ‘P’. Every
week all the particles that are located within this circle
are tracked to determine their individual direction. By averaging
the flow direction of all the individual particles
over a certain time interval, the flow direction is approximated.
The direction of the flow is expressed in the angle
α, which is defined as the angle with respect to the equator.
An angle α of 90o is for example in the direction of the
meridians (North).
In order to check the variation of the flow direction, α was
approximated on a weekly basis for 5 years. The result of
this analysis is visualized in Figure 2.43. It can be seen
that the flow direction actually varies a lot. Even between
two consecutive weeks the direction can change drastically,
with a total range variation of between +90o and
-90o. This variation corresponds to the observations in
chapter 2.6 about the varying surface currents.