Mingjun Wei to present as part of AE Graduate Seminar Series

Dr. Mingjun Wei, Neff Associate Professor in the Mechanical and Nuclear Engineering Department at Kansas State University, will be our next speaker for the Aerospace Engineering Graduate Seminar Series. He will give a presentation titled “Adjoint-based optimization: from jet noise control to flapping-wing aerodynamics” on Monday, April 23 at 4:00pm in 2133 Learned Hall.

Biography

Dr. Mingjun Wei is the Neff Associate Professor in Mechanical and Nuclear Engineering Department at Kansas State University. Dr. Wei received his PhD in Theoretical and Applied Mechanics from University of Illinois at Urbana-Champaign in 2004. He then worked as a postdoctoral associate at Princeton University for two years. From 2006 to 2016, he was at New Mexico State University as an assistant and associate professor, holding MAE Academy Professorship in 2015 and 2016. In 2016, he moved to Kansas State University as an associate professor, currently holding the Harold O. and Jane C. Massey Neff Professorship in Mechanical Engineering. His research has been focused on computational science for simulations, modeling, control and optimization in fluid mechanics with applications in jet noise simulation and control, modeling and optimization of flapping-wing aerodynamics for micro-air vehicles, and simulation and reduced-order models for shock-structure interactions.

Abstract

The adjoint-based approach, by solving an inverse problem to obtain simultaneously the sensitivity with respect to all control parameters, has a computational cost independent of the number of control parameters and becomes an efficient tool for the study of problems with a large control space. In this talk, the basic framework of adjoint-based method is first derived and introduced with its application in jet noise control. Then, its application is extended to our recent study for the understanding of flapping-wing aerodynamics of natural flyers and micro air vehicles.  However, the adjoint equation is typically formulated in a fixed fluid domain. In a continuous formulation, a moving boundary or morphing domain results in the inconsistency in the definition of an arbitrary perturbation at the boundary, which leads to ambiguousness and difficulty in the adjoint formulation if control parameters are related to boundary changes (e.g. the control of wing kinematics and dynamic deformation). Using unsteady mapping function could, in principle, be a remedy, but its formulation is often too complex to be feasible. Instead, we implement the idea of non-cylindrical shape analysis to derive an adjoint-based continuous approach in a rigorous and simple manner particularly for the optimization in moving-boundary problems. Some understanding of flexible flapping wings is presented at the end through the comparison of flows with initial and optimized flapping motions.