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Levich Institute
Steinman Hall, #1M
City College of CUNY
140th Street and Convent Avenue
New York, NY 10031

 

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212-650-8157

 

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212-650-6835

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The Levich Institute is housed in Steinman Hall which is just outside the north campus gate. This building, which underwent a $65 million renovation in recent years, is named after David B. Steinman (Class of 1906), one of the world's greatest bridge builders. Steinman houses CCNY's Grove School of Engineering, named after one of America's most renown engineers, Andrew Grove (Class of 1960), Co-founder and former Chairman of Intel Corp, and Time Magazine’s 1999 “Man of the Year.” The Grove School is the only public school of engineering in New York City, and has seven departments: biomedical, chemical, civil, computer, electrical and mechanical engineering, and computer science. All offer bachelors, masters and doctoral degrees.

 

Albert Einstein Professor Morton Denn, Director of the Benjamin Levich Institute for Physico-Chemical Hydrodynamics (2000-2015) and Professor of Chemical Engineering and Physics at City College, received the Society of Rheology's Distinguished Service Award at the 77th Annual Meeting of the Society in Vancouver on October 17, 2005. Professor Denn, who recently completed ten years as Editor of the Journal of Rheology, is the seventh recipient of the award, which is given at the discretion of the Society's Executive Committee. He received the Society's Bingham Medal for rheology research in 1986. Professor Denn is a member of the National Academy of Engineering and a Fellow of the American Academy of Arts and Sciences, a Guggenheim Fellow and a Fulbright Lecturer, and recipient of numerous awards from the American Institute of Chemical Engineers and the American Society for Engineering Education. He was awarded an honorary D. Sc. by the University of Minnesota in 2001.

This figure shows a well-mixed 10% suspension of monodispersed neutrally buoyant spherical particles in a Newtonian liquid medium in a stationary, partially-filled horizontal Couette device (95% of the available gap volume). These experiments were conducted in Professor Acrivos' Fluid Mechanics laboratory by two of his research assistants, Mahesh Tirumkudulu and Anubhav Tripathi. [Appeared in the March, 1999 issue of the Physics of Fluids]




When the inner cylinder is rotated at 9 rpm, the suspension separates itself into alternating regions of high and low particle concentration along the length of the Couette device. These experiments were conducted in Professor Acrivos' Fluid Mechanics laboratory by two of his research assistants, Mahesh Tirumkudulu and Anubhav Tripathi. [Appeared in the March, 1999 issue of the Physics of Fluids]

Molecular dynamics simulation of the motion of a liquid drop on a solid surface driven by a wettability gradient: a water drop on a self-assembled monolayer of alkanethiol chains terminated with methyl or hydroxl groups, where the (attractive) hydroxl concentration increases from left to right. This is an illustration of Professor Joel Koplik's current research.

Part of Professor Hernan Makse's ongoing research concerns spontaneous stratification in granular mixtures---i.e. the formation of alternating layers of small-rounded and large-faceted grains when one pours a random mixture of the two types of grains into a quasi-two dimensional vertical Hele-Shaw cell---has been recently reported by H. A. Makse, S. Havlin, P. R. King, and H. E. Stanley, "Spontaneous stratification in Granular Mixtures", [ Nature 386, 379 (1997)].

Charles Maldarelli's research activities are in the areas of interfacial fluid mechanics, surfactant interfacial chemistry and nanoscience engineering. Some current topics are:
(1) Remobilizing Surfactants and Their Application to Enhancing the Thermocapillary Migration of Bubbles in a Microgravity Environment:
Bubbles rising in an aqueous phase move as if they had a solid surface rather than a mobile fluid interface. The solidification of the surface is due to the adsorption of surfactant impurities which rigidifies the bubble interface. We have identified surfactants which adsorb to form a mobile monolayer, allowing a bubble to move hydrodynamically as if it had a clean fluid surface. In collaboration with NASA, we are using these surfactants to enhance the thermocapillary migration of bubbles in microgravity. Thermocapillary migration is a method for moving bubbles in space in the absence of buoyancy by applying a temperature gradient. A significant obstacle to its use is the rigidification of the surface of the bubble by surfactant impurities. We are studying using remobilizing surfactants to enhance the migration by forming a mobile monolayer which protects the surface from the adsorption of the impurity.
(2) Gas/Liquid Phase Co-existence of Soluble Surfactants at the Air/Aqueous Interface: Surfactants are used to rapidly reduce the interfacial tension when a new interface is created. Relaxations in tension usually exhibit an initial induction of high tension which can limit the technological use of surfactants in high speed interfacial processes. We have used fluorescence microscopy to demonstrate that the induction is due to a first order phase transition which the assembling monolayer undergoes from a gaseous (G) to a liquid expanded (LE) phase [see the figure of the successive condensation of the liquid phase (bright areas) from the gas phase (dark areas)]. We have also undertaken molecular dynamics simulations to illustrate the phase separation. Birds-eye views of the condensation are shown in the figure. Our molecular level understanding of the induction period allows us to design surfactants which condense more easily and have reduced induction times.
(3) Nanoscience Engineering: We are designing surfaces which can selectively template the heterogeneous nucleation of one polymorph of a crystalline material that exists in several different forms. Our approach is to spatially arrange chemical groups on the surface in such a way as to mimic a crystalline plane of the desired polymorph to insure selective crystallization. We are fabricating nano- island domains of one chemical functionality surrounded by a continuous matrix of a second on a solid surface by using the phase separation of self assembling monolayers. We are currently using these islands as vestibules for the crystallization of nanoplatelets and for the adhesion of proteo-liposomes for surfaces for molecular recognition and sensing.

Mark Shattuck's research activities are currently in the areas of:
Granular Media: Mesoscopic Physics on a Laboratory Scale: The study of granular materials provides insight into poorly understood and vitally important industrial problems, and an unprecedented opportunity to investigate experimentally the theoretical underpinnings of statistical physics. In granular systems, collective behavior and pattern formation can occur with a small number of macroscopic particles. This property creates a unique opportunity to gain a fundamental understanding of mesoscopic systems, such as colloids, lubrication, and nanoscale porous media. The profound link between granular flows and ordinary fluids and is a cornerstone of our research.
Experimental tests of granular kinetic theory: We conduct experiments to directly test granular kinetic theory in the laboratory. From snapshots of a 2D rotating layer of spheres trapped between two glass plates, we extract the velocity field using a temporal cross-correlation technique we developed for dense granular flows. The result is shown to the left as a speed field. We measure the local statistical properties of the grains from close-up high-speed digital photography shown in the lower left image. We developed highly adaptable particle tracking software to extract the velocities of individual particles. The blue and green dots are the centers of the particles in successive frames. From this data, we calculate the histogram of the velocities (small blue dots) that shows excellent agreement with kinetic theory (solid black curve). At moderate rotation rates three flow regimes are formed — a dilute gas at the top, a dense gas in the middle, and an elasto-plastic solid at the bottom. In earlier work, we have confirmed that continuum equations of motion derived using kinetic theory of dense inelastic gases give quantitative results for the dilute phase. We are now exploring their applicability to the dense phase, where we may encounter viscoelastic behavior, which is not currently included in the theory. Finally we are exploring ways of extending kinetic theory and connecting with elasto-plastic solid models to bring the entire flow regime under a unified theory.
Experimental granular rheology: By uniformly exciting a granular media using a random sum of the container's elastic vibration modes, we can directly measure the speed of sound, thermal conductivity, and viscosity as a function of density and granular temperature in this uniformly heated steady state. Using a sinusoidally varying forcing we can measure the frequency dependence of the transport properties. Granular media as an analog for collective systems in extreme conditions: We will study the flow of uniformly heated granular media in a small channel as an analog for mesoscopic systems. We can explore phase transitions in systems of rods, in mixtures of rods and spheres, and in mixtures of different sized spheres. These studies will add to the understanding of both granular media and ordinary condensed matter under extreme situations including confined geometries, gradients that are large on the scale of the mean free path, and flow in which intrinsic mechanical stress can induce phase transitions.

Andreas Acrivos, Albert Einstein Professor of Science and Engineering, Emeritus and former Director of the Levich Institute, was presented the 2001 Medal of Science in Engineering by President George W. Bush at an official ceremony in the White House on June 12, 2002. The National Medal of Science honors individuals in a variety of fields for pioneering scientific research that has enhanced our basic understanding of life and the world around us.

Part of Professor Hernan Makse's research concerns Romanesque networks. Figure to the left is a Fractal vegetable. Fractals are intricately repeated shapes, like the surface of this Romanesque broccoli, in which the parts resemble the whole across several levels of resolution. The work of Song et al.1 indicates that many complex networks, from protein–protein interaction maps to the collaboration graph of Hollywood film actors, are self-similar in much the same way. [NATURE|VOL 433 | 27 JANUARY 2005]

Surfactant Effects on Hydrate Crystallization at the Water.Oil Interface: Hollow-Conical Crystals Prasad U. Karanjkar,†,‡ Jae W. Lee,† and Jeffrey F. Morris*,†,‡ †Levich Institute and ‡Department of Chemical Engineering, City College of City University of New York, New York, New York 10031, United States

ABSTRACT: Clathrate hydrates are icelike crystalline compounds with small guest molecules trapped inside the cages of hydrogen bonded water molecules. Clathrate hydrate crystal growth is studied for the specific case of the guest molecule cyclopentane. Cyclopentane hydrate formation is visualized at a millimeter-scale water drop. Crystal formation takes place at the water.organic interface and has been shown in prior work to occur in a three-step sequence of nucleation, lateral surface growth, and radial growth. This study describes cyclopentane hydrate crystal characteristics during the lateral surface growth and demonstrates the effect of the oil-soluble surfactant sorbitan monooleate (Span 80) on the hydrate crystal growth. A faceted polycrystalline hydrate shell is formed around the water drop in the absence of surfactant. A unique hollow-conical crystal is observed at Span 80 concentrations greater than 0.01% by volume in cyclopentane; the critical micelle concentration is 0.03% Span 80. The conical crystals have a polygonal base, usually hexagonal, which is pinned at the water.cyclopentane interface; growth occurs at this base and drives the previously formed crystal into the water phase. Morphology is dependent upon the growth taking place at the interface where both components of hydrate (i.e., water and cyclopentane) are present at large concentration. The hollow-conical crystals grow to over 100 ěm in linear dimensions in all directions. The morphology described is seen at a range of Span 80 and cyclopentane concentrations. A hypothesis is proposed to relate crowding of surfactant molecules at the interface to the observed hollow-conical crystal shape. [Click here for full article.]

 
 
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