Soft corals vortex-induced dynamics : experimental and numericalstudy
Bibliographic record
Abstract
Soft corals in the Caribbean Sea like the bipinnate sea plume, have a branched geometry and are soft enough to bend under the waves. Due to their cylindrical cross section, a vortex street forms in the coral's wake inducing vibrations transverse to the flow. These vortex-induced vibrations (VIV) are a feeding asset for the coral, enabling it to catch up to 40% more nutrients brought by the flow. If the 2D motion of a cylinder cross section with VIV has been widely studied, the 3D dynamics of a branched structure remains unknown. In this numerical and experimental study, we show how this 3D motion affects the coral feeding. We develop a finite element model of the coral where the cross-flow and in-line VIV are modelled with the wake-oscillator model (WOM). The Euler-Bernoulli beam theory combined with the WOM allow to study the coupled dynamics of the flexible structure. The frame finite element model of the coral colony structure uses the corotational framework to consider large displacements and rotations. The WOM is a phenomenological model for assessing VIV where the action of the wake is modelled by an oscillating lift force, avoiding a costly fully coupled fluid-structure simulation. The lift coefficient follows a Van der Pol oscillator model. Proper orthogonal decomposition separates the trunk and branch motion into vibration modes and characterizes the dynamics. Experimental measurements validate the numerical modes and frequencies. A flexible and elastic model of the soft coral colony is 3D-printed by selective laser sintering. The coral is clamped inside a water loop under a constant uniform flow. Its transverse displacements, captured with a high-speed camera, are compared with the simulations. The influence of the reduced velocity and the number of branches is discussed. Eventually, we conclude on the ability of the coral to feed itself during VIV lock-in better than in static conditions. When engineers usually seek VIV removal from constructions to prevent fatigue, soft corals draw benefits from this instability.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".