The Department of Mechanical, Materials, and Aerospace Engineering presents their spring 2024 seminar series featuring guest speaker Shabnam Raayai-Ardakani, a Rowland Fellow and principal investigator at Rowland Institute at Harvard University, who will give a presentation on “Bio-Inspired Passive Drag Reduction for Single and Multiple Vehicles.” This seminar is open to the public and will take place on Wednesday, February 21, 2024, from 3:30–4:30 p.m. in room 104 of the Rettaliata Engineering Center.

Abstract

Nature uses geometry and arrangements in fascinating ways to control the flow field around individuals and group. For example, the skin of fast-swimming shark species, such as Mako is packed with overlapping micro-scale denticles that are covered with multiple ribs. These textures allow sharks to swim faster than other animals in the ocean. Another is the case of formation flight used by groups of pelicans to minimize the energy required for flying (per pelican) compared to flying solo. In this talk, I will explore the effect of bio-inspired complex geometries and arrangements of solid boundaries on the flow field and how it can be effectively used for reducing the drag of aerial/underwater vehicles.

First, I will focus on shark-inspired two-dimensional textures of various shapes placed aligned in the direction of the flow. I will examine the effect of the location of the textures along the body as well as the shape of the cross-sectional profiles on the ability of textures to alter the flow field. I will specifically focus on the changes in the local shear stress distribution and the overall changes in the drag force. I will show that textures perform better when placed on the suction side of the foil compared with the pressure side, and how the curvature of the profiles affects the local performance of the textures.

Second, I will explore the impact of using arrangements of bodies in the flow inspired by formation flight in pelicans. Here, I will focus on the V-formation and will present our experimental procedure to access the details of the interaction between the wakes of the various members in a water tunnel and discuss the results in terms of the effect of the number of members as well as the packing density of the arrangements. Overall, our results point to all the members in a narrow formation with overlaps in their streamwise projections, experiencing lower drag forces, and observe that increasing the angle of the formation results in moving back to the bodies performing more like separate individuals.

Bio

Shabnam Raayai-Ardakani is a Rowland Fellow and principal investigator at Rowland Institute at Harvard University where her lab is focused on the study of problems of fluid-solid interaction involving textures and complex geometries. Prior to her current role, she was a postdoctoral associate at the Department of Civil and Environmental Engineering at MIT. She received her M.S. and Ph.D. in Mechanical Engineering from MIT and has won multiple awards including the Outstanding Teaching Assistant Award from the Department of Mechanical Engineering at MIT and the Andreas Acrivos Dissertation Award in fluid dynamics from the American Physical Society.pired by formation flight in pelicans. Here, I will focus on the V-formation and will present our experimental procedure to access the details of the interaction between the wakes of the various members in a water tunnel and discuss the results in terms of the effect of the number of members as well as the packing density of the arrangements. Overall, our results point to all the members in a narrow formation with overlaps in their streamwise projections, experiencing lower drag forces, and observe that increasing the angle of the formation results in moving back to the bodies performing more like separate individuals.