Alex Liberzon

Alex Liberzon
Tel Aviv University | TAU · School of Mechanical Engineering

Professor
Looking for collaboration on open source experimental fluid mechanics software

About

221
Publications
72,697
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
2,404
Citations
Citations since 2016
96 Research Items
1477 Citations
2016201720182019202020212022050100150200250
2016201720182019202020212022050100150200250
2016201720182019202020212022050100150200250
2016201720182019202020212022050100150200250
Introduction
Our Laboratory: http://web.eng.tau.ac.il/~alexlib is working in several research areas, all related to the turbulent flows with additives or modifications: 1. Resuspension of particulate materials from smooth and rough surfaces 2. Localized turbulent event (e.g. patch) evolution in stratified turbulent flows 3. Pulsating flows in compliant vessels w/o retrograde flows (blood hemodynamics, wall shear stresses in pulsating flows) 4. Turbulent flows with dilute polymers For those and other applications we develop new experimental methods: 1. real time image processing on hardware (FPGA, GPU) for PIV and 3D-PTV 2. open source software: OpenPIV and OpenPTV 3. Non-linear, active MEMS flow sensors and actuators in collaboration with Prof. Slava Krylov group
Additional affiliations
August 2012 - present
University of Minnesota Twin Cities
Position
  • Turbulence dissipation in a thermally stratified flow
Description
  • Stably thermally stratified tank is forced from the top using the oscillating grid. 3D-PTV and temperature profiles are acquired across the sharp temperature and velocity gradient regions
January 2011 - present
The University of Western Ontario
November 2008 - November 2012
Tel Aviv University
Position
  • Two-way coupling between solid particles and turbulent liquid flow
Education
Technion - Israel Institute of Technology
Field of study
  • Mechanical Engineering

Publications

Publications (221)
Preprint
Full-text available
Discovering a meaningful, dimensionally homogeneous, symbolic expression that explains experimental data is a fundamental challenge in many scientific fields. We present a novel, open-source computational framework called Scientist-Machine Equation Detector (SciMED), which integrates scientific discipline wisdom in a scientist-in-the-loop approach...
Article
Seedless velocimetry is gaining interest in many industrial and research applications. We report on a comparative study of time-resolved optical velocimetry using traditional, mirror-type knife-edge schlieren optics versus Background-Oriented Schlieren (BOS) of subsonic round turbulent helium jets in air at Red = 5890 and 11,300. Digital images wit...
Article
Full-text available
Ulva is a widespread green algal genus with important ecological roles and promising potential as a seagriculture crop. One of the major challenges when cultivating Ulva is sudden biomass disappearance, likely caused by uncontrolled and unpredicted massive sporulation. However, the dynamics of this process are still poorly understood. In this study...
Preprint
Full-text available
Seedless velocimetry is gaining interest in many industrial and research applications. We report on a comparative study of time-resolved optical velocimetry using traditional, mirror-type, knife-edge schlieren optics versus Background-Oriented Schlieren (BOS) of subsonic round turbulent helium jets in air at $Re_d = 5,890$ and 11,300. Digital image...
Article
We study properties of the turbulent/nonturbulent interface (TNTI) between two layers of stratified fluids through direct numerical simulations (DNSs). Zero mean shear forcing creates moderate turbulence in one of the layers with the Taylor microscale Reynolds numbers in the mixed region of Reλ=35,44. We focus on the similarities and differences of...
Article
Bifurcation-based sensors, implementing stability boundaries monitoring in bistable microstructures, may manifest higher sensitivity and robustness when compared to their statically operated counterparts. In the operation of these devices, two key questions arise: 1) how to reliably identify the critical events associated with the transition betwee...
Article
Full-text available
Olfactory navigation is defined as a task of a self-propelled navigator with some sensors capabilities to detect odor (or scalar concentration) convected and diffused in a windy environment. Known for their expertise in locating an odor source, male moths feature a bio-inspirational model of chemosensory. Many studies have developed moths-inspired...
Preprint
Full-text available
Ulva is a widespread green algal genus with important ecological roles and promising potential as a seagriculture crop. One of the major challenges when cultivating Ulva is sudden biomass disappearance, likely caused by uncontrolled and unpredicted massive sporulation. However, the dynamics of this process are still poorly understood. In this study...
Article
Full-text available
We suggest improving minimally-invasive stenosis severity estimation, using a combination of existing geometry-based methods with Transluminal Attenuation Gradient measurements. Instead of local flow values, the method uses flow distribution ratios along the entire tree. The tree geometry is used to derive a lumped model and predict the ‘theoretica...
Article
There is accumulating evidence that male insects advertise their quality to conspecific females through pheromones. However, most studies of female released sex pheromone assume information transfer regarding merely the species of the female and her mating status. We show that more information is conveyed through the female sex pheromone, positioni...
Article
Full-text available
Multi-scale macroalgae growth models are required for the efficient design of sustainable, economically viable, and environmentally safe farms. Here, we develop a multi-scale model for Ulva sp. macroalgae growth and nitrogen sequestration in an intensive cultivation farm, regulated by temperature, light, and nutrients. The model incorporates a rang...
Preprint
Full-text available
There is accumulating evidence that male insects advertise their quality to conspecific females through pheromones. However, most studies of female released sex pheromone assume information transfer regarding merely the species of the female and her mating status. We show that more and precise information is conveyed through the female sex pheromon...
Article
Full-text available
The aortic arch aneurysm is a complex disease that requires branching of one or more aortic arch vessels and can be fatal if left untreated. In this in vitro study, we examine the effect of the treatment approach on the unsteady hemodynamics and blood perfusion to the upper vessel's in models of an aortic arch aneurysm, and of the three common repa...
Article
Metal particles in solid propellants enhance rocket engines performance. An interaction of particles with a high Reynolds number turbulent gas flow accelerating to a nozzle, has not been characterized thoroughly. We study the particle-turbulence interactions in a two-dimensional model of a rocket engine. Two-phase particle image/tracking velocimetr...
Article
Full-text available
Background: The outbreak of COVID-19 pandemic highlighted the necessity for accessible and affordable medical ventilators for healthcare providers. To meet this challenge, researchers and engineers world-wide have embarked on an effort to design simple medical ventilators that can be easily distributed. This study provides a simulation model of a s...
Preprint
Full-text available
Multi-scale macroalgae growth models are required for the efficient design of sustainable, economically viable and environmentally safe farms. Here, we develop a multi-scale model for Ulva sp. macroalgae growth and nitrogen sequestration in an intensive cultivation farm, regulated by temperature, light and nutrients. The model incorporates a range...
Article
Full-text available
Lagrangian stochastic models are widely used to predict and analyze turbulent dispersion in complex environments, such as in various terrestrial and marine canopy flows. However, due to a lack of empirical data, it is still not understood how particular features of highly inhomogeneous canopy flows affect the Lagrangian statistics. In this work, we...
Article
An approach for gas flow velocity measurement at two different closely located points using a simple device incorporating only one thermal sensing element, is introduced and the feasibility to determine different velocities is experimentally demonstrated. An electrostatically actuated initially curved bistable microbeam heated by an electric curren...
Article
Objective In vitro evaluation of aspiration of viscous hyaluronic acid (HA) fillers through dermatologic needles, with and without a new solution for safe aspiration with a saline flashing procedure. The final objective is to be able to offer an easy‐to‐use device for a practitioner who injects fillers under and into the skin blindly. This device a...
Preprint
Full-text available
We present an open-source MATLAB package, entitled OpenPIV-Matlab, for analyzing particle image velocimetry (PIV) data. We extend the PIV analysis with additional tools for post-processing the PIV results including the estimation of aero/hydrodynamic forces from the PIV data of a wake behind an immersed (bluff or streamlined) body. The paper presen...
Article
Full-text available
We present an open-source MATLAB package, entitled OpenPIV-MATLAB, for analyzing particle image velocimetry (PIV) data. We extend the PIV analysis with additional tools for post-processing the PIV results including the estimation of aero/hydrodynamic forces from the PIV data of a wake behind an immersed (bluff or streamlined) body. The paper presen...
Preprint
Full-text available
Background: Reduced coronary flow reserve in aortic stenosis and after transcatheter aortic valve implantation is usually attributed to physiological factors taking place during systole, such as an increase in coronary resistance, and backward waves intensity. In this paper, we suggest an additional factor related to the diastolic hemodynamics in t...
Article
Full-text available
Background Reduced coronary flow reserve in aortic stenosis and after transcatheter aortic valve implantation is usually attributed to physiological factors taking place during systole, such as an increase in coronary resistance, and backward waves intensity. In this paper, we suggest an additional factor related to the diastolic hemodynamics in th...
Preprint
Full-text available
Metal particles in solid propellants enhance rocket engines performance. An interaction of particles with a high Reynolds number turbulent gas flow accelerating to a nozzle, has not been characterized thoroughly. We study the particle-turbulence interactions in a two-dimensional model of a rocket engine. Two-phase particle image/tracking velocimetr...
Article
Full-text available
Offshore cultivation of marine macroalgae is a potential sustainable resource for fuel, food, and chemicals. Offshore, the high productivity of macroalgae cultivation depends on external nitrogen supply. The current work examines the idea of supplying nitrogen for Ulva sp. cultivation in the oligotrophic Eastern Mediterranean Sea (EMS) by artificia...
Article
Full-text available
We study parametric resonance (PR) of double-clamped micro-beams that are electro-thermally actuated by a time-dependent Joule’s heating and cooled by a steady air flow. The developed model demonstrates applicability of such device as a bifurcation-based flow velocity sensor. An AC electric current through the beam induces a time-harmonic compressi...
Article
We report on a simple yet efficient approach allowing direct electrothermal excitation of parametric resonance (PR) in double-clamped flexible nano- and microscale beams. The application of a time-harmonic voltage between the beam's ends leads to the electric current and Joule's heating of the entire beam, which induces a time-periodic axial stress...
Preprint
Full-text available
Lagrangian stochastic models are widely used for making predictions and in the analysis of turbulent dispersion in complex environments, such as the terrestrial canopy flows. However, due to a lack of empirical data, how particular features of canopy phenomena affect the parameterizations of Lagrangian statistics is still not known. In the followin...
Article
We perform a series of experiments to measure Lagrangian trajectories of settling and rising particles as they traverse a density interface of thickness h using an index-matched water-salt-ethanol solution. The experiments confirm the substantial deceleration that particles experience as a result of the additional force exerted on the particle due...
Preprint
Full-text available
Olfactory navigation in insects, for instance when males search for mates, is a navigational problem of a self-propelled agent with limited sensor capabilities in a scalar field (odor) convected and diffused by turbulent wind. There are numerous navigation strategies proposed to explain the navigation paths of insects to food (flowers) or mating pa...
Article
Full-text available
Direct estimation of Lagrangian turbulence statistics is essential for the proper modeling of dispersion and transport in highly obstructed canopy flows. However, Lagrangian flow measurements demand very high rates of data acquisition, resulting in bottlenecks that prevented the estimation of Lagrangian statistics in canopy flows hitherto. We repor...
Code
Male moths can locate remote females using pheromone filaments across large distances in a strongly turbulent vegetated areas. This repository provides a computational framework to understand the possible navigation methods and compare their performance. Useful for indoor localization, GPS-less navigation and ecology, among others.
Article
Particle Image Velocimetry (PIV) data processing time can constrain dataset size and limit the types of statistical analyses performed, particularly when investigating turbulence. General purpose Graphics Processing Unit (GPU) computing has been shown to accelerate PIV data processing, but larger datasets and accompanying higher order statistical a...
Article
Full-text available
Increasing biomass production yields is a critical challenge for macroalgae biorefineries. The continuous tumbling and mixing of free‐floating algae through water or airflow has been shown to increase the productivity of algae in land‐based cultivation systems. This approach has not been tested thoroughly in offshore cultivation. We report, here, a...
Preprint
Full-text available
We perform a series of experiments to measure Lagrangian trajectories of settling and rising particles as they traverse a density interface of thickness h using an index-matched water-salt-ethanol solution. The experiments confirm the substantial deceleration that particles experience as a result of the additional force exerted on the particle due...
Article
Objective To analyze the intrarenal hydrodynamic processes and clearance of stone fragments during percutaneous nephrolithotomy (PCNL) using numerical and physical models. Materials and methods COMSOL multiphysics software was used to simulate irrigation flows and transport of particles in a kidney model based on computerized tomographic acquisiti...
Article
We report on a flow velocity measurement technique based on snap-through detection of an electrostatically actuated, bistable micromechanical beam. We show that induced elecro-thermal Joule heating, and the convective air cooling change the beam curvature and consequently, the critical snap-through voltage (VST). Using single crystal silicon beams,...
Article
We propose to combine the active vortex generators with the particle image velocimetry (PIV) measurements and post-processing streamwise vortex characterization algorithms into a feedback based closed-loop control system for wind turbine applications. We develop two vortex identification and characterization methods that use PIV realizations for th...
Preprint
Full-text available
Diagnostic angiography procedures assess the severity of the patient's coronary arteries stenosis due to atherosclerosis by either examining the visual information, or using hemodynamically based parameters. X-ray angiographic procedures are considered the ‘‘gold standard’’ for minimally-invasive determination of anatomical information, such as lum...
Preprint
Full-text available
We report on a flow velocity measurement technique based on snap-through detection of an electro-statically actuated, bistable micromechanical beam. We show that induced electro-thermal Joule heating and the convective air cooling change the beam curvature and consequently the critical snap-through voltage (VST). Using single crystal silicon beams,...
Preprint
Full-text available
We propose an extension to the three dimensional particle tracking velocimetry (3D-PTV) method and apply it to Lagrangian measurements of turbulent flow in a large scale wind tunnel. The proposed extension is based on a novel real-time image analysis, that is preformed on a dedicated hardware. The extension significantly reduces the amount of store...
Preprint
Full-text available
We report on a flow velocity measurement technique based on snap-through detection of an electrostatically actuated, bistable micromechanical beam. We show that induced elecro-thermal Joule heating and the convective air cooling change the beam curvature and consequently the critical snap-through voltage ($V_{ST}$). Using single crystal silicon bea...
Preprint
Full-text available
We propose an extension to the three dimensional particle tracking velocimetry (3D-PTV) method and apply it to Lagrangian measurements of turbulent flow in a large scale wind tunnel. The proposed extension is based on a novel real-time image analysis, preformed on a dedicated hardware. The extension significantly reduces the amount of stored data a...
Article
Full-text available
Some female moths attract male moths by emitting series of pulses of pheromone filaments propagating downwind. The turbulent nature of the wind creates a complex flow environment, and causes the filaments to propagate in the form of patches with varying concentration distributions. Inspired by moth navigation capabilities, we propose a navigation s...
Article
Full-text available
We present a generalization of turbulent pair dispersion to large initial separations (η<r0<L), by introducing a new time scale, τv0, that reflects the persistence of initial conditions at time τ=0. Results of 3D Lagrangian tracking experiments at moderate Reynolds numbers show that pairs, for which the new time scale is shorter than the eddy turno...
Data
Dispersion visualization of Lagrangian trajectories from a puff source.
Data
Dispersion visualization of Lagrangian trajectories from a puff source.
Article
Full-text available
During diastole, coronary perfusion depends on the pressure drop between the myocardial tissue and the coronary origin located at the aortic root. This pressure difference is influenced by the flow field near the closing valve leaflets. Clinical evidence is conclusive that patients with severe aortic stenosis (AS) suffer from diastolic dysfunction...
Chapter
Aggregates grown in mild shear flow are released, one at a time, into homogeneous isotropic turbulence where their breakup is recorded by three-dimensional particle tracking velocimetry (3D-PTV). The aggregates have an open structure with fractal dimension around 2.2, and their size varies from 0.9 to 3.1 mm which is large compared to the Kolmogoro...
Chapter
We summarize in this contribution our quest toward characterization of a 3D coherent structure. The study started with the microbubble flow visualization experiments of Gad Hetsroni and his co-authors back in the 1990s and expanded during 1999-2003 study using particle image velocimetry (PIV) and proper orthogonal decomposition (POD). The topology...