Many important scientific and engineering problems require predictions of fluid structure interaction FSI. Aeroelastic flutter, a positively reinforced coupling between the aerodynamic forces on an…

This federal contract award, with ID NNX16AP15A, was issued by NASA to The Regents of the University of California, doing business as the University of California, Berkeley (UC Berkeley). The $694,933.45 cooperative agreement supports research into high-order methods for fluid-structure interaction (FSI) problems, which are critical for predicting aeroelastic flutter and other complex fluid-structure phenomena. The research aims to develop advanced algorithms and simulation capabilities, including discontinuous Galerkin methods and adjoint techniques, to enable more reliable and accurate FSI modeling across a range of aerospace and engineering applications. There is no set-aside designation for this award. As the parent organization, the State of California Controller's Office would administer any resulting task orders. This contract award aligns with NASA's broader interest in advancing high-fidelity computational modeling and simulation to support the design and performance of air vehicles and other aerospace systems.

Many important scientific and engineering problems require predictions of fluid structure interaction FSI. Aeroelastic flutter, a positively reinforced coupling between the aerodynamic forces on an object and the natural mode of the object, can produce large and potentially destructive vibrations in aircraft, turbines, and other structures. If during each oscillation the energy transferred to the structure is greater than the energy naturally dissipated, the amplitude of oscillation will increase. If this amplitude continues to grow the mechanical structure may not be able to withstand the internal stresses and may fail. Even if the structure does not fail, flutter may cause undesirable vibrations or noise. FSI may also be useful in understanding flapping flight or producing biologically inspired micro aerial vehicles. These problems often involve multiple scales and non linear effects, which makes IT challenging to solve even relatively simple problems accurately. One of the most promising ways to increase the fidelity of these simulations is to use high order accurate methods. These have the potential to produce fundamentally more reliable solutions than traditional numerical schemes. Much of the current research is devoted to discontinuous galerkin DG methods because of its many attractive properties, such as the arbitrary order discretizations, the use of fully unstructured simplex meshes, and the natural stabilization mechanism based on approximate riemann solvers. One of the significant challenges in high fidelity FSI is the transfer of forces and displacements between the fluid and structure domains along with the need for mesh deformation. The current research is devoted to fully coupled monolithic FSI methods because of the need for ensuring time accurate simulations and conservation of momentum and energy between the fluid and structure domains. Furthermore, our research handles the mesh deformation using an arbitrary lagrangian eulerian ALE formulation. Another significant challenge in high fidelity FSI is the computation of the gradient of an output with respect to a large number of parameters. Our research develops adjoint techniques to compute the derivative information for both steady state and unsteady FSI problems. Implicit explicit imex runge kutta schemes are employed for high order accurate simulation of unsteady FSI problems. The high order FSI algorithms we develop will be demonstrated on benchmark problems to validate their fidelity, as well as on relevant applications with varying levels of nonlinearities and complex geometries to clearly establish their advantages. We will pay most attention to flutter analysis of an aircraft wing to demonstrate all capabilities including convergence, time accurate simulation, scalability, and sensitivities. High fidelity flutter analysis can offer a better understanding and improved performance of air vehicle design. We would look to collaborate with NASA to integrate the FSI algorithms and the corresponding software developed in this research into NASA simulation codes. Through such collaborations, the final product will have the potential for a broader impact.