Drogueless Stokes Drifter Design for Surface Current Measurement
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Solution Overview
Problem
Existing surface drifting buoys struggle to isolate and measure Stokes drift effects at the water surface due to their design, which often minimizes wind force effects but also diminishes Stokes drift force, making it difficult to monitor water surface circulation effectively.
Innovation Solution
The development of small, drogueless drifters with a low-profile design that minimizes wind exposure while maximizing Stokes drift force, featuring a thin shape that allows the device to flip and operate seamlessly regardless of orientation, equipped with sensors and antennas for data collection and communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sea anchor (drogue) is added to the drifter, then the drifter's stability and ability to measure surface currents is improved, but the drifter's ability to measure Stokes drift is worsened because the drogue minimizes Stokes drift force effects
Solution Approach 1:
The patent removes the sea anchor (drogue) component from the drifter system entirely. By eliminating the drogue, the drifter no longer experiences the force minimization effect that prevented Stokes drift measurement, while the core floating and sensing functions are maintained through the buoy and sensor assembly.
Solution Approach 2:
Instead of using a drogue to stabilize the drifter and measure currents, the patent inverts the approach by using a drogueless design that allows the drifter to be stabilized by wave forces and current forces acting directly on the buoy body, thereby enabling Stokes drift measurement through the natural interaction of the buoy with water surface motion.
2Object-affected harmful factors
If the drifter profile is minimized to reduce wind exposure, then wind force effects are reduced, but the Stokes drift force effects are also diminished
Solution Approach 1:
The patent optimizes the buoy's geometric parameters (size, shape, and profile) to achieve a balance where the buoy is sufficiently compact to reduce wind exposure but maintains adequate cross-sectional area and volume to capture sufficient Stokes drift force. The buoy dimensions are specifically tuned so that the ratio of water interaction area to air exposure area maximizes Stokes drift measurement while minimizing wind interference.
3Measurement precision
If the drifter is designed with a thin profile to maximize Stokes drift force, then Stokes drift measurement is improved, but the drifter's stability and self-righting capability is worsened
Solution Approach 1:
The patent incorporates ballast elements positioned within the buoy to create a low-center-of-gravity configuration. This ballast acts as a counterweight that provides restoring torque when the buoy is tilted or flipped, enabling the thin-profile buoy to self-right and maintain operational stability without requiring a bulky shape or drogue attachment.
Solution Approach 2:
The patent designs the buoy with dynamic stability characteristics where the thin profile allows the buoy to flex and rotate with wave motion, and the ballast system provides active self-righting capability. This dynamic design enables the buoy to maintain measurement capability through various orientations while recovering from capsizing events.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables precise measurement of Stokes drift and other water characteristics like temperature and salinity, improving surface current tracking, oceanographic research, and environmental monitoring by isolating Stokes drift effects at the water surface.
Implementation Method 1
A surface drifting buoy, hereafter referred to as a drifter, is an instrument that approximately follows water at the water surface. Drifters are defined by their geometry and positive buoyancy, which constrains them to follow the two-dimensional flow at the water surface or near surface.
Implementation Method 2
Monitor Stokes drift effects on water surface circulation
Data Source
AI summary
The present disclosure relates to drifters that float and take measurements at, or very near, a surface of a body of water. The drifters may have a design that reduces wind force effects but does not diminish Stokes drift force effects. The drifters may have two opposing exterior surfaces with antennas and sensors on each of the opposing surfaces so that the drifters may always utilize at least some of the antennas and sensors, regardless of the drifter's orientation in the water.