Two NSF Awards Support Fluid-Structure Interaction Research
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Yahya Modarres-Sadeghi, a professor in the UMass Amherst Mechanical and Industrial Engineering (MIE) Department and an associate dean in the College of Engineering, is the principal investigator on two weighty grants from the National Science Foundation (NSF). The first award, for $499,993 over three years, will support a project on “Modeling Fluid-structure Interactions Between Flexible Structures and Inertial Viscoelastic Flow.” The second award, totaling $439,053 for three years, will enable a project on “Modeling the Influence of Turbulence on Flow-induced Instabilities of Large Flexible Structures with Innovative Applications in Wind-turbine Blades.”
The first of his two NSF awards is based on a continuing collaboration between Modarres-Sadeghi and Professor Jonathan Rothstein of the UMass Amherst MIE department, the co-principal investigator on this newly funded NSF grant. The project focuses on the general field of viscoelastic FSI (VFSI), in which viscoelastic fluid flow interacts with a flexibly mounted or flexible structure. This new project focuses on flexible structures in a VFSI system and aims at understanding these interactions by conducting a series of numerical simulations and synergistic experiments.
Since most of the structures in FSI systems found in nature and in industry are flexible, it is critical to understand the influence of viscoelasticity on flexible structures. By pursuing such an understanding, this project will have a transformative impact on our understanding of FSI systems.
A number of important canonical cases will be considered, including cases in which: the structure is a flexible sheet placed parallel to the incoming flow (the flapping-flag problem); wall-mounted flexible structures are placed in flow (terrestrial and aquatic plants); and the structure with a circular or square cross-section is placed in crossflow (vortex-induced vibrations and galloping). Through these experiments, the project aims at investigating a technique for suppressing or possibly enhancing the flow-induced motion of these flexible structures in real-world applications.
The second NSF grant, received in collaboration with Northeastern University Civil and Environmental Engineering Professor Luca Caracoglia, supports research that promises a new dynamic model for FSI systems, with a focus on large offshore-wind-turbine blades.
“The project will promote safe design of next-generation, offshore-wind-turbine structures by enabling slender and lighter blade designs,” as Modarres-Sadeghi explains.
The research will provide indications about various thresholds of aeroelastic instability in wind-turbine blades, along with the most appropriate simulation and analysis approaches for novel designs of longer, and therefore more efficient, wind-turbine blades.
Although FSIs have been predicted to occur for such new wind-turbine-blade designs, predictions are often based on deterministic models without the influence of flow-turbulence and load variability. This project will address this critical gap by combining experimental measurements and theoretical modeling to derive a novel model that accounts for the influence of turbulence on the onset of instability and post-critical behaviors.
This research aims to make fundamental contributions to accelerate the use of stochastic and probabilistic structural dynamics to examine the pre- and post-critical behavior of fully coupled, FSI systems with asymmetric structures and subjected to three-dimensional flows that can undergo nonlinear dynamic instabilities. The project will achieve this goal by producing models that describe turbulence effects and more accurately consider the aeroelastic loads, which are relevant to highly flexible and asymmetric structures such as wind-turbine blades.
The researchers will disseminate and integrate the findings of both these NSF-funded research projects into outreach programs for K-12 students and teachers by creating new modules for different courses, hosting high-school classes, and broadening research opportunities for students from under-represented minority groups. (October 2024)