Publications by Karen Ann J Mulleners

Highly deformable flapping membrane wings suppress the leading edge vortex in hover to perform better

Airborne insects generate a leading edge vortex when they flap their wings. This coherent vortex is a low-pressure region that enhances the lift of flapping wings compared to fixed wings. Insect wings are thin membranes strengthened by a system of veins th ...

2025

Highly agile flat swimming robot

Herbert Shea, Karen Ann J Mulleners, Mrudhula Baskaran

Navigating and exploring the surfaces of bodies of water allow swimming robots to perform a range of measurements while efficiently communicating and harvesting energy from the Sun. Such environments are often highly unstructured and cluttered with plant m ...

AMER ASSOC ADVANCEMENT SCIENCE2025

Data from: Event-based reconstruction of time-resolved centreline deformation of flapping flags

Karen Ann J Mulleners

This directory contains open-source data and code obtained at the UNFoLD laboratory at EPFL. This code implements a new tracking method for fast deformation of flapping flags using an event-based camera. Sampled data from experimental results as well as si ...

Zenodo2024

Data from: Optimal blade pitch control for enhanced vertical-axis wind turbine performance

Sébastien Le Fouest, Karen Ann J Mulleners

This directory contains open-source data obtained using a single-bladed H-type vertical-axis wind turbine prototype with individual blade pitching. This data results from the optimisation of the blade's pitching kinematics using a genetic algorithm at two ...

Zenodo2024

Data from: Highly deformable flapping membrane wings suppress the leading edge vortex in hover to perform better

Karen Ann J Mulleners, Alexander Gehrke

This directory contains open-source data obtained at the UNFOLD laboratory at EPFL. The data got recorded for the flexible membrane wings with different stiffnesses expressed by the aeroelastic number Ae and recorded at different angles of attack. More in ...

Zenodo2024

Self-exploring automated experiments for discovery, optimization, and control of unsteady vortex-dominated flow phenomena

Karen Ann J Mulleners

Typical unsteady vortex-dominated flows like those involved in bio-inspired propulsion, airfoil separation, bluff body wakes, and vortex-induced vibrations can be prohibitively expensive to simulate and impossible to measure comprehensively. These examples ...

American Physical Society (APS)2024

Eel-like robot swims more efficiently with increasing joint amplitudes compared to constant joint amplitudes

Auke Ijspeert, Kamilo Andres Melo Becerra, Karen Ann J Mulleners, Alexandros Anastasiadis

This paper is associated with a video winner of a 2023 American Physical Society’s Division of Fluid Dynamics (DFD) Gallery of Fluid Motion Award for work presented at the DFD Gallery of Fluid Motion. ...

American Physical Society (APS)2024

Optimal blade pitch control for enhanced vertical-axis wind turbine performance

Sébastien Le Fouest, Karen Ann J Mulleners

Vertical-axis wind turbines are great candidates to enable wind power extraction in urban and off-shore applications. Currently, concerns around turbine efficiency and structural integrity limit their industrial deployment. Flow control can mitigate these ...

Nature Research2024

Time scales of dynamic stall development on a vertical-axis wind turbine blade

Sébastien Le Fouest, Karen Ann J Mulleners, Daniel Marie Fernex

Vertical-axis wind turbines are excellent candidates to diversify wind energy technology, but their aerodynamic complexity limits industrial deployment. To improve the efficiency and lifespan of vertical-axis wind turbines, we desire data-driven models and ...

2023

Strength and timing of primary and secondary vortices generated by a rotating plate

Karen Ann J Mulleners, Diego Francescangeli

Accurate predictions of how vortices grow, evolve, and separate from aerodynamic objects are desirable for various applications ranging from autonomous aerial vehicles to wind turbines. Here, we present an experimental characterisation of the formation pro ...

2023

Review of rotating wing dynamic stall: Experiments and flow control

Karen Ann J Mulleners

2023

Identification of the trade-off between speed and efficiency in undulatory swimming using a bio-inspired robot

Auke Ijspeert, Laura Isabel Paez Coy, Kamilo Andres Melo Becerra, Karen Ann J Mulleners, Alexandros Anastasiadis, Eric Daniel Tytell

Anguilliform swimmers, like eels or lampreys, are highly efficient swimmers. Key to understanding their performances is the relationship between the body’s kinematics and resulting swimming speed and efficiency. But, we cannot prescribe kinematics to livin ...

Nature Research2023

Reconfiguring it out: How flexible structures interact with fluid flows

Karen Ann J Mulleners, Mrudhula Baskaran

Amer Physical Soc2023

Proprioceptive Sensing of Soft Tentacles with Model Based Reconstruction for Controller Optimization

Karen Ann J Mulleners, Nana Obayashi, Josephine Anna Eleanor Hughes, Francesco Stella

2023

Modulation of the Leading-Edge Vortex Shedding Rate in Discrete-Vortex Methods

Karen Ann J Mulleners, Guosheng He

A new method to determine the rate of circulation fed into a leading-edge vortex (LEV) is presented for discrete-vortex methods (DVM). The strength of vortex particles shed from the leading edge is calculated based on the velocity at the shear layer, which ...

2022

To tread or not to tread: comparison between water treading and conventional flapping wing kinematics

Karen Ann J Mulleners, Swathi Badala Krishna, Alexander Gehrke

Hovering insects are limited by their physiology and need to rotate their wings at the end of each back-and-forth motion to keep the wing's leading edge ahead of its trailing edge. The wing rotation at the end of each half-stroke pushes the leading edge vo ...

IOP Publishing Ltd2022

Tapered foils favor traveling-wave kinematics to enhance the performance of flapping propulsion

Karen Ann J Mulleners, Pedro Miguel Nunes Pereira de Almeida Reis, Matteo Pezzulla

We report results from an experimental investigation on the fluid-structure interactions of flapping foils with tapered thickness profiles actuated in a quiescent viscous fluid. We seek to assess the propulsive performance of two sets of flapping foils; on ...

2022

Lagrangian analysis of bio-inspired vortex ring formation

Karen Ann J Mulleners, Mrudhula Baskaran

Pulsatile jet propulsion is a highly energy-efficient swimming mode used by various species of aquatic animals that continues to inspire engineers of underwater vehicles. Here, we present a bio-inspired jet propulsor that combines the flexible hull of a je ...

2022

Vortex Dislocation In The Near Wake Of A Cylinder With Span-Wise Variations In Diameter

Karen Ann J Mulleners

We examined the evolution of three-dimensional vortex shedding patterns induced by spanwise variations of the cylinder diameter. Two distinct types of shedding patterns have identified through flow visualization: continuous (in-phase) oblique shedding wher ...

International Symposium on the Application of Laser and Imaging Techniques to Fluid Mechanics2022

Estimating the non-dimensional energy of vortex rings by modelling their roll-up

Karen Ann J Mulleners, Guillaume de Guyon-Crozier

The non-dimensional energy of starting vortex rings typically converges to values around 0.33 when they are created by a piston-cylinder or a bluff body translating at a constant speed. To explore the limits of the universality of this value and to analyse ...

Cambridge University Press2022