Uncovering new mechanisms in biological and engineering architectured materials
Presented by Professor Pablo D. Zavattieri
Lyles School of Civil Engineering, Purdue University
Our ability to improve more than one mechanical property in most engineering materials has been somewhat limited in the past by the inherent inverse relation between these desired properties often found in man-made materials. On the other side, Nature has evolved efficient strategies to synthesize materials that often exhibit exceptional mechanical properties that significantly break those trade-offs. In fact, most biological composite materials achieve higher toughness without sacrificing stiffness and strength in comparison with typical engineering material. Interrogating how Nature employs these strategies and decoding the structure-function relationship of these materials has opened up a new set of concepts in materials engineering. Considering the current progress in material synthesis and manufacturing, these new concepts have converged to the field of architectured materials. In this talk, I will describe some interesting mechanics problems that we encountered as we studied some extraordinary species, and how we can translate these lessons learned to architectured materials. In particular, I will focus on two different examples: One is related to Bouligand architectures, a naturally-occurring architecture typically found in arthropods such as the Mantis Shrimp, and its capability to promote delocalization to mitigate catastrophic failure. The second example is related to a family of architecture materials whose unit cells have multiple stable configurations inspired by competing auxetic mechanisms found in Nature. Implementation of some of those ideas to cellular architectured material guided us to the development of reusable energy absorbing materials.
Dr. Pablo Zavattieri is a Professor of Civil Engineering and University Faculty Scholar at Purdue University. Zavattieri received his BS/MS degrees in Nuclear Engineering from the Balseiro Institute, in Argentina and PhD in Aeronautics and Astronautics Engineering from Purdue University. He worked at the General Motors Research and Development Center as a staff researcher for 9 years, where he led research activities in the general areas of computational solid mechanics, smart and biomimetic materials. His current research lies at the interface between solid mechanics and materials engineering. His engineering and scientific curiosity has focused on the fundamental aspects of how Nature uses elegant and efficient ways to make remarkable materials. He has contributed to the area of biomimetic materials by investigating the structure-function relationship of naturally-occurring high-performance materials at multiple length-scales, combining state-of-the-art computational techniques and experiments to characterize the properties. His current research program includes the study of naturally-occurring architectures and the translation to engineering materials. Prof. Zavattieri is the recipient of the NSF CAREER award, the Roy E. & Myrna G. Wansik Research Award, he is a National Academy of Engineering Frontiers of Engineering Alumnus and a National Academy of Science Kavli Frontier of Science Fellow. He was also appointed a Purdue University Faculty Scholar for the period 2015-2020.
4:10-4:35 p.m. Presentation
“Bubble Rising Velocity in Strong Turbulence”
Presented by ASHWANTH SALIBINDLA (Prof. Rui Ni)
For bubbly ship wakes and breaking waves, the mean rising velocity of bubbles determines their residence time inside the carrier phase and the resulting surface bubble concentration over time. We carried out an experimental study of the rising velocity of bubbles with size ranging from 1 mm to 10 mm. A vertical water tunnel V-ONSET has been developed to generate strong turbulence with a large energy dissipation rate (ϵ~0.1 m2/s3) and a controllable mean flow. In this presentation, I will introduce the facility and also talk about some results regarding the rise velocity of bubbles in turbulence. We will compare our results with previous experimental and numerical works in this area.
4:35-5:00 p.m. Presentation
“Spatio-Temporal Dynamics of Turbulent Flows in the Presence Of Waves”
Presented by PATRICIO CLARK DI LEONI (Profs. Tamer Zaki & Charles Meneveau)
Waves, eddies, horizontal winds, vortices, and many other structures can coexist and interact in a turbulent flow. Their identification and extraction in simulations and experiments is a major challenge. We show how, with the aid of spatiotemporal spectra, we can study the interplay between waves and eddies in rotating, free surface, stratified and quantum flows. We present results on the existence of a mixed regime of waves and solitons in surface wave turbulence, links between inertial waves and the development of large-scale horizontal winds in stratified turbulence, quantification of bounds for the validity of wave turbulence in rotating flows, and links between the depletion of helicity and kelvin waves in quantum turbulence.
Harnessing thermal expansion in architected metamaterials
Presented by Professor Damiano Pasini
Mechanical Engineering, McGill University
For technology called to function under harsh temperature swings, e.g. satellite antennas, thermal expansion can be an enemy to fight against. But for others, e.g. deployable systems, thermal expansion can be an ally. In this seminar, I will contribute to address challenges currently existing on both fronts: i) how to meet strict requirements of thermal expansion in ultralightweight stiff materials, ii) how to engage temperature in morphable materials that deploy in situ under extreme conditions. The approach that I will follow draws from concepts of mechanics, geometry, materials, and structural optimization, through a combination of theory, computation and mechanical testing for performance validation.
Damiano Pasini is the Louis Scholar of the Faculty of Engineering at McGill University and Professor of Mechanical Engineering. His research interests lie in solid mechanics, advanced materials and structural optimization with current focus on mechanical metamaterials. He is fully engaged in understanding their mechanics, introducing reliable predictive models, and using them to engineer, build and test architected materials with optimally tuned functional properties that are of practical use in aerospace and other disciplines.
4:10-4:35 p.m. Presentation
“A Novel Particle Tracking Technique using a Scanning Laser Setup Tested via Numerical Experiment”
Presented by MELISSA KOZUL from NTNU (Host: Prof. Tamer Zaki)
Lagrangian particle tracking relying on line-of-sight based volumetric methods is challenged by high particle densities, required for the adequate spatial resolution of high Reynolds-number flows. This presentation will introduce a novel robust 3D particle tracking technique based on a scanning laser setup. We have developed an effective triangulation greatly reducing ghost particle reconstruction using images from only two cameras. Following successful reconstruction of a time series of 3D particle fields, Lagrangian velocities and accelerations are calculated using particle tracking. The method was developed via numerical experiment using the Johns Hopkins Turbulence Database.
4:35-5:00 p.m. Presentation
“Scale Separation in Restricted Nonlinear Wall-Bounded Turbulence”
Presented by BENJAMIN MINNICK (Adviser: Prof. Dennice Gayme)
Numerical and experimental studies have revealed the significance of streamwise coherent structures in wall-bounded turbulence, both near the wall where energy is dissipated and far from the wall where energy is carried. Engineering applications have prompted the study of wall-bounded turbulent flows however, the computational expense of resolving the necessary scales has limited our ability to interrogate the mechanisms underlying the flow. Recently the restricted nonlinear (RNL) model has been proposed. Motivated by these streamwise coherent structures inherent in wall-bounded turbulence, the RNL model neglects nonlinear interactions between nonzero streamwise Fourier modes thereby reducing the order of the streamwise varying dynamics. At low Reynolds number, the RNL model has been shown to accurately predict first-and second-order statistics while retaining as few as one nonzero Fourier mode. Extending to more moderate Reynolds numbers, this model correctly captures log-law behavior, provided the streamwise dynamics are band-limited to dissipative scales. In this work, we move the RNL modeling paradigm to even higher Reynolds numbers, in a regime where a separation of scales is expected. We present results of current efforts and identity additional phenomena to properly capture scale separation.
Fast and efficient underwater propulsion inspired by biology
Presented by Professor Alexander Smits
Mechanical and Aerospace Engineering, Princeton University
Biology offers a rich source of inspiration for the design of novel propulsors with the potential to overcome and surpass the performance of traditional propulsors for the next generation of underwater vehicles. To-date, however, we have not achieved the deeper understanding of the biological systems required to engineer propulsors with the high speed and efficiency of animals like sailfish, tuna, or dolphins. What is the underlying physics of the fluid-structure interaction of bio-propulsors that results in the superior performance observed in nature? Moreover, how do we replicate this performance in the next generation of man-made propulsors? Can we push beyond the limits of biology? By studying the performance of simple heaving and pitching foils, we have identified the basic scaling that describes the thrust, power and efficiency, under continuous as well as burst-coast actuation. These scaling relationships allow us to identify the natural limits on simple bio-inspired propulsors, and suggest that further improvements in performance will require adaptive flexibility and optimized profiles.
Dr. Smits is the Eugene Higgins Professor of Mechanical and Aerospace Engineering at Princeton. His research interests are centered on fundamental, experimental research in turbulence and fluid mechanics. In 2004, Dr. Smits received the Fluid Dynamics Award of the American Institute of Aeronautics and Astronautics (AIAA). In 2007, he received the Fluids Engineering Award from the American Society of Mechanical Engineers (ASME), the Pendray Aerospace Literature Award from the AIAA, and the President’s Award for Distinguished Teaching from Princeton University. In 2014, he received the Aerodynamic Measurement Technology Award from the AIAA. He is a Fellow of the American Physical Society, the American Institute of Aeronautics and Astronautics, the American Society of Mechanical Engineers, the American Academy for the Advancement of Science, the Australasian Fluid Mechanics Society, and he is a Member of the National Academy of Engineering. He is currently the Editor-in-Chief of the AIAA Journal.
4:10 pm Presentation
“Deformation and Breakup of Bubbles in Strong Turbulence”
Presented by ASHIK ULLAH MOHAMMAD MASUK (Adviser: Prof. Rui Ni)
In oceanic wave breaking, a large amount of air bubbles are produced in the turbulent upper layer of the ocean, which controls many important natural processes such as ocean-atmosphere gas exchange and aquatic environment for marine life. One of the limiting factors to understand such processes is our knowledge on the behavior of bubbles in such a violent turbulent environment. Therefore, we experimentally study the dynamics of bubble deformation and breakup in a turbulent flow with high energy dissipation rate ( ) through simultaneous measurements of both carrier and dispersed phases. In this presentation, a novel method to reconstruct the 3D geometry of bubbles from optical measurements of turbulent multiphase flow will be introduced. Furthermore, experimental observations of the breakup mechanism of Hinze scale bubbles will be discussed.
4:35 pm Presentation
“Energy-Based Control of Wall-Bounded Shear Flows”
Presented by CHANG LIU (Adviser: Prof. Dennice Gayme)
This work examines the use of energy methods to design a feedback control law for channel flow. This approach has advantages over linear methods that may lead to control law that are only effective in small regions of attraction around a base state. In particular, we design a control law based on the Lyapunov stability applicable to nonlinear systems, allowing them to enlarge the controllable flow region. The fluctuation energy in the shear flows is a typical candidate for a Lyapunov function(al) to prove stability of a base flow, resulting in the classical Reynolds-Orr equation. This work uses this framework to design a control law that achieves stability through suppressing the shear production term in this energy equation. This control law is initially illustrated in a nine-dimensional Galerkin model of plane Couette flow and then demonstrated in the Direct Numerical Simulation (DNS) of turbulent channel flows. The results reveal that the base flow is stabilized through this control law, which has the potential to relaminarize a turbulent flow.
Autonomy by Composition
Presented by Professor Daniel E. Koditschek
Alfred Fitler Moore Professor of Electrical and Systems Engineering , University of Pennsylvania
I will review decades of effort by my students and collaborators that aims to achieve robot architectures capable of autonomous work at useful tasks in varied environments by developing a systematic method for behavioral composition. Twenty years after inventing the first legged machine to run freely in the natural world, we have endowed it with a behavioral suite that achieves autonomous ascent of thinly forested outdoor hills as well as all indoor stairwells found on the Penn Engineering campus. Further development of its sensorimotor resources and behavioral repertoire may yield a partly autonomous outdoor lab assistant for geoscientists fighting desertification and other environmental impacts. Our new platform, the first gearless legged robot, affords unprecedented proprioceptive sensitivity that we exploit to task it with a growing suite of autonomous mobile manipulation chores entailing rearrangement of moveable objects around it. The common ingredient in all these task specifications and executions is a reliance on formal parallel and sequential compositions of hybrid dynamical attractor basins. Time permitting, I will close with speculative remarks concerning the prospects of achieving by this line of research a formal language for programming autonomous physical work in suitable sensorimotor architectures.
Daniel E. Koditschek is the Alfred Fitler Moore Professor of Electrical and Systems Engineering, within the University of Pennsylvania School of Engineering and Applied Science where he serves as Director of the Penn Engineering Research Collaboration Hub (PERCH). Koditschek received his bachelor’s degree in Engineering and Applied Science and his M.S. and Ph.D. degrees in Electrical Engineering in 1981 and 1983, all from Yale University. He served on the Yale Faculty in Electrical Engineering until moving to the University of Michigan a decade later. In January 2005, he moved to Penn as Chair of the recently formed Electrical and Systems Engineering Department, a position which he held through 2012. Koditschek’s research interests include robotics and, more generally, the application of dynamical systems theory to intelligent mechanisms. His more than 200 archival journal and refereed conference publications have appeared in a broad spectrum of venues ranging from the Transactions of the American Mathematical Society through The Journal of Experimental Biology, with a concentration in several of the IEEE journals and related transactions. Various aspects of this work have received mention in general scientific publications such as Scientific American and Science as well as in the popular and general lay press such as The New York Times and Discover Magazine.
Here is a sample of some recent mentions in the popular press. Dr. Koditschek is a member of the AMS, ACM, MAA, SIAM, SICB and Sigma Xi and is a Fellow of the IEEE and the AAAS. He was awarded the 2016 IEEE Robotics and Automation Society Pioneer Award. Koditschek holds secondary appointments within the School of Engineering and Applied Science in the departments of Computer and Information Science and Mechanical Engineering.
4:10 pm Presentation
“Displacement Thickness-Based Recycling Inflow Generation Method For Spatially Developing Turbulent Boundary Layer Simulations”
Presented by SAMVIT KUMAR (Advisers: Profs. Meneveau & Mittal)
An improved method for generation of turbulent inflow for simulations of developing boundary layers is presented. The approach is based on prior recycling methods for flow over smooth (Lund et al., 1998) and rough (Yang and Meneveau, 2015) surfaces. Both these methods rely on obtaining δ99 from the mean velocity profiles based on a velocity threshold. Since this value is heavily dependent on the shape of the profile, it can be very noisy and can suffer from large undesirable fluctuations, even when the profiles are time averaged. A profile-integrated quantity, such as the displacement thickness, can be used instead of δ99. In the recycling method, mean and fluctuation velocities on a sample plane are rescaled, combined and recycled back to the inlet, as the inflow velocity. A roughness-length related scale is chosen for rescaling of the inner layer, depending on the surface geometry and the displacement thickness is chosen instead of δ99 as the length scale to rescale the outer layer. The blending function, dependent on both the inner and the outer length scales, is used to combine the two profiles, to obtain the inflow velocity. Since the displacement thickness depends on the profile shape, an iterative scheme is implemented. This cushions the effect which an unusual mean velocity profile at the sampling plane may have on the value of the outer length scale and hence, on the rescaled velocity profile. Some applications and test cases are presented.
4:35 pm Presentation
“Data-Driven Analysis of Aeroelastic Flutter”
Presented by KARTHIK MENON (Adviser: Prof. Rajat Mittal)
Data-driven methods to analyze fluid flows have been recently gaining popularity in many subdomains of fluid dynamics – from turbulence to reduced-order aerodynamic models. This has been primarily driven by our improved ability to generate large, high-quality data sets, and efforts to extract patterns from large amounts of data in an efficient manner. This talk will describe our initial work to understand the dynamics of aeroelastic flutter from one such data set consisting of over 500 simulations of a pitching airfoil under different conditions. In particular, the focus will be on our efforts to characterize all the possible vortex wakes behind the airfoil using a machine learning-inspired clustering method. We will also discuss our development of a Dynamic Mode Decomposition formulation that allows accurate decomposition of the flow around a moving boundary, which has until now remained a challenge for large amplitude boundary motion.
Modulating the Therapeutic Microenvironment using Nanostructured Biomaterials
Presented by Professor Tejal Desai
University of California, San Francisco
The field of nanomedicine offers great potential to revolutionize clinical care, including medical devices, regenerative medicine, and molecular imaging approaches. Recent advancements in nanofabrication applied to biocompatible materials lay the groundwork for creating biomaterials with a high level of control at the molecular scale. These subtle interactions with cell and tissue assemblies can modulate properties such as mechanotransduction, adhesion, and immune activation. Nanostructured biomaterials may offer potential advantages over conventional drug delivery strategies by enhancing molecular transport and uptake. In this talk, I will discuss our recent work in developing nanostructured materials for protein and cell-based delivery as well as injectable micro/nanoscale materials for the modulation of fibrosis and immune activation. By gaining a better understanding of how small scale topographies can influence the biological microenvironment, we can design platforms for applications in therapeutic delivery and tissue regeneration.
Tejal Desai is the Ernest L Prien Endowed Professor and Chair of the Department of Bioengineering and Therapeutic Sciences within the Schools of Pharmacy and Medicine at the University of California, San Francisco (UCSF), the director of the NIH training grant for the Joint Graduate Program in Bioengineering at the University of California, Berkeley (UCB) and UCSF, and the founding director of the UCSF/UC Berkeley Masters Program in Translational Medicine. She was recently named the Inaugural Director of the UCSF Engineering and Applied Sciences Initiative known as HIVE (Health Innovation Via Engineering). Professor Desai’s research spans multiple disciplines including materials engineering, cell biology, tissue engineering, and pharmacological delivery systems to address issues concerning disease and clinical translation. She has published over 220 peer-reviewed articles, holds numerous patents, and is currently the founder of 5 start-up companies. Her research is at the cutting-edge in precision medicine, enabled by advancements in micro and nanotechnology, engineering, and cell biology directed to clinical challenges in disease treatment. By taking advantage of the current understanding of how cells respond to engineered materials and the fabrication of well-defined extracellular microenvironments, she seeks to design new platforms to overcome existing challenges in therapeutic delivery.
Her research efforts have earned recognition including Technology Review’s “Top 100 Young Innovators”, Popular Science’s Brilliant 10, and NSF’s New Century Scholar. Some of her other honors include the Eurand Grand Prize Award for innovative drug delivery technology, the Young Career Award from the Engineering in Medicine and Biology Society (IEEE EMBS), the Dawson Biotechnology award, and both the UC Berkeley and Brown University Distinguished Engineering Alumni awards. Recently, she was named Chair of the American Institute for Medical and Biological Engineering College of Fellows. In 2015, she was elected to the National Academy of Medicine. Professor Desai is a vocal advocate for STEM education and outreach to underrepresented minority students, collaborating with educational groups such as the Lawrence Hall of Science and the Exploratorium. She received her B.S. from Brown University in biomedical engineering and was awarded a Ph.D. in bioengineering jointly from UCSF and UCB.
Celebrate student innovation and creativity at the annual Johns Hopkins Engineering Design Day. Through poster sessions, presentations, and prototype demonstrations, Hopkins engineers will demonstrate their ability to apply knowledge and skills to tackle real-world challenges.
*Mechanical Engineering Senior Design Day will be held in Hodson Hall:
Presentations (Session 1): 10 a.m. to 12 p.m. (210 and 213 Hodson Hall)
Poster Session: 12 to 2 p.m. (Hodson Hall, 2nd Floor Lobby)
Presentations (Session 2) and Closing Ceremony: 2 to 5 p.m. (210 and 213 Hodson Hall)
Visit designday.jhu.edu for the full schedule of events.