Wave Tank Testing at NRL
Corrosion imposes an estimated $20 billion annual burden across the U.S. Department of Defense. An often-overlooked driver is the seawall itself. Conventional seawalls have flat, reflective faces that bounce wave energy back rather than absorbing it—worsening erosion at the wall toe, raising the risk of overtopping, and generating sea spray aerosols that drift across a base and accelerate corrosion on ships, aircraft, and infrastructure across a wide radius.
Kind Designs’ Living Seawalls™ are engineered to do the opposite. Their biomimetic, 3D-printed geometry dissipates incoming wave energy instead of reflecting it, having the potential to also reduce the sea spray aerosols that fuel corrosion across an installation.
To quantify this potential advantage, Kind Designs partnered with the U.S. Naval Research Laboratory (NRL) to conduct physical wave tank testing of its 3D-printed Living Seawall™ technology. The project—funded through a NAVSEA SBIR Phase I grant and conducted as part of the DoD’s Environmental Security Technology Certification Program (ESTCP)—directly compared flat concrete seawalls against 3D-printed wave-dissipating geometries, measuring differences in both wave energy absorption and sea spray aerosol generation.
Research Objectives
Quantifying Wave Absorption and Sea Spray Reduction
The goal of the study was to measure how much advantage wave-dissipating 3D-printed geometries offer over a conventional flat seawall. Specifically, the research set out to:
- Measure wave attenuation — quantify how effectively Kind Designs’ 3D-printed structures reduce reflected wave energy relative to a flat seawall.
- Measure sea spray aerosols — determine whether those structures reduce the production of sea spray aerosols compared to a flat seawall.
- Inform next-generation design — identify the structural features that maximize both wave dissipation and aerosol reduction.
- Establish credibility for military applications — NAVSEA/NRL validation provides a higher standard of confidence than university testing alone.
Beyond quantifying performance, positive results could shape recommendations for how shoreline resilience is approached at military installations, offering a new standard for protecting waterfront bases against wave energy, erosion, and corrosion in the future.
Methodology
The flat wall and Kind Designs seawall was installed in the NRL wave tank and subjected to a range of incoming waves of varying wavelength and amplitude. Wave gauges recorded both the incoming and reflected wave packets; the difference between them yields an absorption coefficient for each design, with the flat wall serving as the worst-case benchmark. Sea spray particle concentrations were measured above each design to estimate aerosol production rates.
Designs tested:
- Flat wall (reference benchmark)
- “Sound Wall” — a new geometry inspired by sound-absorption technology, on the premise that shapes that absorb sound waves may also absorb water waves
- “Sound Wall” with simulated “marine growth” — fibrous carbon electrodes woven between the wedges to mimic how a mature living wall would appear to an oncoming wave (softer, more porous)
Wave conditions: discrete wave packets and continuous wave trains (30 and 150 waves).
Key Findings
1. Wave Dissipation
The “sound wall” geometry proved to be a highly effective wave energy absorber. Performance improved as waves became shorter and steeper: in the most extreme case tested—a 2 m wavelength with 10 cm amplitude—the “sound wall” design absorbed an additional 52% of wave energy compared to the flat-wall benchmark.
Testing also revealed the mechanism behind this performance. The wedges capture wave motion through a wide opening beneath the planter and channel it back as jets—similar to the blowhole effect seen along limestone shorelines in South Florida and the Bahamas. Once broken into jets, the reflected energy is no longer organized wave motion; it dissipates into turbulence, and the waves do not reform.
2. Sea Spray Aerosols
Key:
- “Sound wall” Living Seawall
- “Sound wall” Living Seawall with “marine growth”
- Flat seawall
The “sound wall” with simulated “marine growth” consistently produced less sea spray aerosols than the other designs—evidence that a mature, biologically colonized wall surface further suppresses the aerosols that drive corrosion.
Practical Applications
Real-World Benefits for Coastal Resilience
Kind Designs’ 3D-printed Living Seawall™ panels are the only NAVSEA-validated coastal infrastructure product that simultaneously dissipates rather than reflects wave energy, reduces sea spray aerosols, satisfies environmental mitigation requirements through ecological habitat recruitment, and shortens construction timelines through rapid, vertical, additive-manufacturing methods—all in a single product.
The benefits extend well beyond the military. While the value is clearest for bases protecting highly corrosive and expensive assets, the same reduction in sea spray and wave energy translates to lower maintenance costs for any private, commercial, or public waterfront property—from corroding park benches and playground equipment to moored vessels.
Ongoing Research
These NRL results are guiding the next iterations of Kind Designs’ wave-dissipating geometries, optimizing for both wave absorption and sea spray reduction. The data also feeds Kind Designs’ broader CFD modeling program, enabling predictive design and region-specific adaptation of Living Seawalls™ for coastlines across the United States.
Our ultimate goal: to make Living Seawalls™ the new global standard for coastal infrastructure.