Collaborative research: propulsion in the middle ground: using animal models to evaluate propulsion hydrodynamics at lower intermediate reynolds numbers

The National Science Foundation Division of Chemical, Bioengineering, Environmental, and Transport Systems awarded Roger Williams University $199,559 on July 15, 2026, under the Engineering program (CFDA 47.041) to investigate propulsion hydrodynamics in small animals and translate findings into engineering designs for robotic vehicles and biomedical devices.

The research will use high-speed imaging, fluid velocity and pressure measurements, and computational fluid simulations to study how representative organisms—using jetting, body undulation, and coordinated paddling—achieve efficient propulsion at intermediate Reynolds numbers where neither fluid inertia nor viscosity dominates. Experimental measurements will be integrated with computational models to identify fluid-structure interactions responsible for enhanced performance and develop predictive relationships linking body motion to flow characteristics. The project will support undergraduate and graduate research experiences, develop K–12 educational materials, and engage the public through partnerships with marine science organizations.

Performance is scheduled from the award date through June 30, 2029, with work conducted in Bristol, Rhode Island.

Abstract

Engineering models suggest that small animals face a difficult physical challenge when they move through water. Models predict that fluid transport is surprisingly inefficient on the scale of small animals. Yet many small animals routinely outperform these predictions, swimming faster and moving water more effectively than expected. Understanding how these animals accomplish this feat is important because similar constraints limit the performance of small pumps, medical devices, and underwater vehicles. This project will investigate how animals have repeatedly solved this problem throughout evolutionary history and determine whether those solutions can inspire improved engineering designs. The project will also provide interdisciplinary research experiences for undergraduate and graduate students, develop educational materials for k?12 classrooms, and engage the public through partnerships with marine science organizations and outreach programs. Project outcomes will support manufacturing and use of robotic vehicles and innovations in biomedical device design. This project will determine the physical mechanisms that allow animals to achieve high transport efficiency in a flow regime where neither fluid inertia nor viscosity dominates. The investigators will study representative organisms that use three major forms of propulsion: jetting, body undulation, and coordinated paddling. High-speed imaging will be combined with measurements of fluid velocity, pressure, and energetic cost to quantify the interactions between moving bodies and surrounding fluids. The experimental measurements will be integrated with computational fluid simulations to identify the fluid-structure interactions responsible for enhanced performance. The resulting datasets will be used to develop predictive relationships linking body motion, flow conditions, energy expenditure, and transport efficiency across a critical range of flow environments. The research will advance fundamental understanding of fluid mechanics and biomechanics while providing design principles relevant to small-scale propulsion and pumping technologies. The project will support interdisciplinary workforce development, participation of undergraduate researchers in cutting-edge science, creation of inquiry-based educational materials for k?12 audiences, and dissemination of discoveries through public outreach and marine science education programs. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the foundation's intellectual merit and broader impacts review criteria.- subawards are not planned for this award.