The concept was derived by observing fish propulsion. Fish use alternating lift and generate well-organized vortical wakes. VIVACE mimics this fluid-structure interaction without copying complex fish kinematics.
The core technological gap in Marine Hydrokinetic (MHK) energy is harvesting slow flows (below 3 knots). These slow flows correspond to lower Reynolds numbers, which represent the vast majority of untapped ocean and river currents.
Both VIV and Galloping are fluid-structure interaction (FSI) phenomena, but they operate differently. VIV is a nonlinear resonance phenomenon—there is synchronization between force (from alternating vortices) and motion. Think of it as an oscillator with a natural frequency that changes with flow speed because the added mass changes.
Galloping is not resonance. It is an instability of the shear layers resulting in negative drag in the direction transverse to the flow. The shed vortices do not cause the instability; sometimes they help, and sometimes they act adversely. It only appears like resonance because structures (or our frames) have a limited range to oscillate.
Typically, galloping produces more power than VIV, but it comes with trade-offs. The efficiency goes down because the swept area increases, which means you need a wider frame to take advantage of the galloping power. Additionally, galloping initiates at higher flow speeds than VIV.
Ideally, a VIVACE Converter is designed with soft springs to capture slow speeds, proper turbulence stimulation to trigger galloping early after VIV, and precise positioning to ensure neither phenomenon is suppressed.
The system relies on transverse (up-and-down) vibrations caused by alternating pressure imbalances (vortex shedding). Linear transverse motion directly drives the Power Take-Off (PTO) linear generator most efficiently.
VIVACE is orientation-agnostic. Field tests in the St. Clair river have successfully utilized both horizontal (tandem) and vertical cylinder deployments.
Constructive interference (synergistic FIO) occurs when downstream cylinders synchronize with the upstream vortical wake to amplify power. Destructive interference occurs due to hydrodynamic shielding, where downstream cylinders encounter depleted, slower flow.
You use dampers to harness energy. That is the fundamental way mechanical energy is extracted from the system. Just like friction is required for a car to drive uphill (you cannot walk on ice because there is no friction), damping provides the necessary resistance to capture power.
This specific mass ratio balances structural durability with the exact buoyancy and kinematic response needed to trigger Flow-Induced Oscillations (FIO) at target flow speeds.
VIVACE utilizes Passive Turbulence Control (PTC) via surface roughness to selectively trigger VIV and galloping across varying speeds.
VIVACE relies heavily on Adaptive Damping rather than active motion control. Instead of using energy-consuming active control to physically manipulate the cylinders into synchronization, the harnessing damping of the Power Take-Off (PTO) is dynamically adjusted. This allows the cylinders to naturally precipitate into high-yield, fish-undulation oscillatory patterns.
Cylinders reverse direction due to the hard physical limitations of the structural frame.
The system inherently minimizes moving parts compared to turbines. Redesigns utilize advanced, watertight IP69 enclosures (like Blue Robotics boxes) and optimized wheeled carts to manage friction and seal integrity.
Managing "hydrodynamic shielding" to prevent power loss in downstream units, and optimizing the spacing and staggering of the array.
Yes. Dedicated, validated Computational Fluid Dynamics (CFD) codes and an Eigen-Relation Solution are used to model the fluid-structure interface and predict parametric bifurcations.
No. Synchronization is achieved naturally through adaptive damping and fluid-structure interaction, completely avoiding the use of active manipulation.
The forces are not enhanced; they are different. The rear cylinders may be hydrodynamically shielded and therefore encounter slower (less energetic) flow depending on the array spacing. Adjusting mass strictly for "enhanced" force is a misconception of the fluid-structure interaction occurring in the wake.
You can deploy more than 4 cylinders in an array, but adding them in excessively close, continuous proximity yields diminishing returns. As energy is extracted by the upstream cylinders, the downstream wake loses kinetic energy (hydrodynamic shielding). Proper spacing and staggering are required to maintain high power density in larger arrays.
It is a fundamental aspect of the biomimetic design. The cylinders move quietly and slowly (only ~20% faster than the flow). The alternating lift generates a well-organized vortical wake that matches natural fish-school dynamics. Fish naturally seek out these vortical wakes as they reduce the energy required for them to swim, turning the array into an artificial reef rather than a hazard.
Exceeding optimal density leads to immediate hydrodynamic shielding, where downstream cylinders encounter depleted flow.
Metrics are aligned with natural Strouhal frequencies of fish. Testing matrices include varying aspect ratios, spacing, and mass ratios to maintain a wake structure suitable for aquatic life.
While energy generation is the primary market, VIVACE arrays intrinsically serve as habitats because they operate without blades, rotors, or dams and move at fish-compatible speeds.
Unlike standard tidal turbines, VIVACE contains no blades, rotors, or dams. The oscillation is entirely transverse and controlled by the physical limitations of the supporting frame and the adaptive damping of the PTO, completely eliminating the risk of blade strikes to marine life.
Water is roughly 800 times denser than air, giving water-based MHK an unparalleled power density (602W/m³ compared to a wind farm's 0.01W/m³). While the physics apply to air, wind applications would require massive swept areas to match the energy yield.
Research actively focuses on "coexistence"—triggering galloping immediately after VIV to create an open-ended Response Amplitude Operator (RAO) for continuous power generation across all speed ranges.
Yes. The design includes modifying circular cylinders with Passive Turbulence Control (surface roughness) and incorporating specific "fish-tail parameters" to alter the geometry and enhance Flow-Induced Oscillations.
The system has been thoroughly modeled using Den Hartog’s equations for quasistatic instability, nonlinear spring/damping models, and Eigen-Relation solutions at the fluid-structure interface.