4/6/2023 Julia Park 4 min read
Written by Julia Park
Mechanical metamaterials are engineered structures that have unique properties that are not possible with natural materials. However, their effects on turbulent flows around air vehicles is currently unknown.
Researchers from University of Illinois Urbana-Champaign, California Institute of Technology, University of Pennsylvania, and Boston University have been awarded a Multidisciplinary University Research Initiative (MURI) grant from the Air Force Office of Scientific Research (AFOSR) to study how different classes of mechanical metamaterials interact with dynamics of turbulent flows. Their findings are expected to result in transformative changes to the energy requirements and flight envelope of air-vehicle operation—imperative to the sustainability and superiority of the Department of Defense energy ecosystem.
The project, “Fluid‐Metamaterial‐Interaction to Revolutionize Passive Control of Aerodynamic Flows,” is a collaboration between fluids and structures mechanics experts to marry expertise in turbulent flow dynamics, fluid-structure interaction (FSI), and advances in materials science, mechanics, and manufacturing to enable an intelligent pairing of carefully chosen mechanical metamaterials with fundamental flows that embody key barriers to improved air vehicle flight.
Some mechanical metamaterials have complex responses to loads, including frequency-dependent responses, directionally dependent responses, and the ability to respond differently depending on which global equilibrium point they start in. The researchers plan to use these advanced capabilities of metamaterials to couple to and modify complex and problematic fluid dynamic behaviors to improve the performance of advanced vehicles, including reducing drag and enhancing maneuverability.
Department of Mechanical Science and Engineering professor Katie Matlack will lead the seven-person team, which includes UIUC Department of Aerospace faculty Andres Goza, Phillip Ansell, Theresa Saxton-Fox; Cal Tech professor Jane Bae; UPenn professor Jordan Raney; and Boston University professor Harold Park.
This MURI program will leverage an initial collaboration between Matlack, Goza, and Ansell funded through the Grainger College of Engineering's Strategic Research Initiative, in which they created a computational and experimental framework with which to study phononic flow control. The program will also build off ongoing AFOSR funding that Goza and Matlack received in which FSI between simplified metamaterials and 2D aerodynamic flows are being simulated.
Matlack and colleagues will establish a new multidisciplinary field – fluid-metamaterial interaction (FMI) – and aim to discover new fluid-structure coupling between innovative materials and critical aerodynamic flows to enable passive control of transition delay, drag reduction, and separation.
“I am thrilled to have the opportunity to establish this new field. Many mechanical metamaterials exhibit mechanical and dynamic properties that actually have quite complementary features to fundamental challenges in passive flow control. But this is a highly complex domain that involves many disparate disciplines, so there’s been very few efforts to push that forward until now. This multidisciplinary program will enable us to tackle the intersection between these domains,” Matlack said. “The program will also open some multidisciplinary opportunities for graduate students, including dedicated collaborations with the Air Force Research Lab.”
The researchers’ expertise spans all areas of FMI: multiple classes of mechanical metamaterials, architected materials, advanced manufacturing, computational mechanics, FMI simulations, experimental turbulent dynamics, experimental fluid dynamics, and turbulence modeling. Their work will introduce new engineering tools, including high-fidelity computational frameworks, reduced-order model paradigms, coupled experimental methodologies, and manufacturing capabilities.
The FMI discovered through this program are anticipated to produce transformative leaps in our scientific understanding of FSI. For the DoD, this work will result in surface/subsurface structural systems to make passive, dynamic flow control within next-generation air vehicles a reality.
“Realizing that the structures and surfaces of aerospace vehicles can be engineered with designed properties—uniquely tailored responses to forcing at different frequencies, different reactions to flow directionality, and efficient transfer of mechanical energy across space—it opens up a new world of possibilities for passive control of flows,” Ansell said.
Saxton-Fox agrees. “In the long term, this work will enable vehicles that can safely and efficiently maneuver through complex environments. In the short term, we aim to provide fundamental insights into the metamaterials design, the coupling between the metamaterial and the fluid, and the fluid dynamics response to jumpstart the field FMI field and enable novel aircraft designs.”