Session: Rising Stars of Mechanical Engineering Celebration & Showcase

Paper Number: 150385

150385 - Three-Dimensional Fluid-Structure Interaction Diagnostics Using a Single Camera 

The interplay between fluid dynamics and structural mechanics gives rise to a cascade of effects, where changes in flow motion and surface deformation become intricately linked at the interface of the fluid and the structure. The relationship between fluid and structure is reciprocal: structural motion alters the boundary conditions at the fluid interface, causing fluctuations in pressure and/or viscous forces, and the interaction at the fluid-structure interface can lead to changes in structural motion. Thus, fluid-structure interaction (FSI) is a multiphysics interaction that is integral to understanding many applications including biomechanics, turbomachinery, aeroelastic coupling, sedimentation, hydro-elasticity, etc. For most FSI problems, analytical solutions to the physically coupled equations are challenging to obtain, and while experimental methods are improving, they are still limited in scope. Therefore, the predominant choice to investigate FSI physics has been numerical simulations with good progress over the last few decades starting from loosely coupled 2D FSI methods to tightly coupled 3D simulations. On the other hand, experimental methods have primarily focused on lower-fidelity decoupled approaches with flow field measurements obtained separately from one- or two-dimensional structural motion.

In this poster, a new method for FSI diagnostics to simultaneously capture time-resolved three-dimensional, three-component (3D3C) velocity fields and structural deformations using a single light field camera is presented. A light field camera encodes both spatial and angular information of light rays collected by a conventional imaging lens that allows for the 3D reconstruction of a scene from a single image. Building upon this capability, a light field fluid-structure interaction (LF FSI) methodology is developed with a focus on experimental scenarios with low optical access. Proper orthogonal decomposition (POD) is used to separate particle and surface information contained in the same image. A correlation-based depth estimation technique is introduced to reconstruct instantaneous surface positions from the disparity between angular perspectives and conventional particle image velocimetry (PIV) is used for flow field reconstruction. Validation of the methodology is achieved using synthetic images of simultaneously moving flat plates and a vortex ring with a small increase in uncertainty under ~ 0.5 microlenses observed in both flow and structure measurement compared to independent measurements. The method is experimentally verified using a flat plate translating along the camera's optical axis in a flow field with varying particle concentrations. Finally, simultaneous reconstructions of the flow field and surface structure around a flexible membrane are presented, with the surface reconstruction further validated using simultaneously captured stereo images. The findings indicate that the LF FSI methodology provides a new capability to simultaneously measure large-scale flow characteristics and structural deformations using a single camera.

Presenting Author: Vrishank Raghav Auburn University

Presenting Author Biography: Vrishank Raghav is an Associate Professor with 7 years of research experience in applying fluid dynamics across multiple disciplines including aeronautics, space exploration, bioinspired engineering, and biomedical engineering. As an educator, he is passionate about innovating and incorporating novel active learning techniques into the classroom to improve learning outcomes.

Authors:

Vrishank Raghav Auburn University