Session: ASME Undergraduate Student Design Expo

Paper Number: 173171

Design and Validation of a Cyber-Physical Fluid Dynamics System for Bio-Inspired Propulsion Studies 

Unsteady fluid–structure interactions play a central role in bio-inspired propulsion and energy harvesting, yet remain difficult to model due to complex time-dependent forces, vortex dynamics, and coupled motion. To experimentally study these effects under controlled and reconfigurable conditions, a cyber-physical fluid dynamics (CPFD) system was developed. In this system, mechanical properties such as mass, stiffness, damping, and moment of inertia are implemented virtually through software rather than physical components. At each control step, feedback from a rotary encoder and 6-axis force/torque sensor is used to solve the mass–spring–damper equation, and the resulting force or torque is applied to a brushless DC servomotor. This architecture enables the system to respond dynamically to external forces—whether from fluid loading or physical interaction—while behaving as if governed by a customizable mechanical model.

The physical setup consists of a dual-axis actuation platform that drives a 3D-printed hydrofoil in pitch and heave inside a recirculating water channel. Motion is controlled using real-time PID loops operating at a 4 kHz sampling rate, supported by a high-resolution data acquisition card. All virtual parameters are adjustable during runtime, enabling systematic variation of structural properties without hardware modification. To ensure accurate force reproduction, the control system includes compensation for parasitic inertial effects and suppression of unintended damping arising from the motor and support structure.

The system was experimentally developed and tuned through an iterative process involving hardware characterization, sensor calibration, and dynamic testing. Free-decay experiments were used to determine the physical mass moment of inertia and damping using logarithmic decrement and linear regression. A wide set of forced oscillation tests was conducted across different frequencies, stiffness values, and damping ratios. Results showed that the system could accurately replicate the desired dynamic response, maintaining errors below 5% even under high-frequency actuation.

In addition to baseline validation, the system is capable of operating in asymmetric modes. One axis can be driven with predefined trajectories while the other remains passive or semi-constrained, enabling experiments in passive energy extraction and fluid-structure coupling. More complex motion strategies—such as phase-shifted pitching and heaving—can be tested to mimic bio-inspired swimming gaits or optimize propulsion efficiency.

The CPFD framework also provides opportunities for real-time adaptation, optimization, and learning. By varying virtual parameters in closed loop with sensor data, the platform can support future integration of adaptive control strategies, flow estimation, or bio-inspired reflexes. It is well suited for investigating nonlinear response, resonance phenomena, and the interaction between actuation and passive structural behavior. Overall, this system offers a powerful and flexible testbed for studying unsteady hydrodynamics, control in a physically grounded yet dynamically reconfigurable environment.

Presenting Author: Abylaikhan Mukhamejanov Lehigh University

Presenting Author Biography: I am an undergraduate researcher at Lehigh University, majoring in Mechanical Engineering. My work focuses on cyber-physical systems, experimental fluid dynamics, and bio-inspired propulsion. I currently conduct research in the Unsteady Flow Interactions Laboratory, under the guidance of Professor Keith Moored, where I have been developing a dual-axis cyber-physical platform for testing dynamic hydrofoil motion in a water channel.

My project involves integrating real-time control, sensor feedback, and virtual dynamic models to study unsteady fluid–structure interaction under controlled conditions. I have also served as the Structures Lead for Lehigh’s NASA CubeSat team and have experience in systems engineering through previous research and internship positions.

Authors:

Abylaikhan Mukhamejanov Lehigh University
Ata Ardic Lehigh University
Keith Moored Lehigh University