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The Dynamic Interfacial Phenomena Investigations on Mobile Fluid Surfaces: Experimental Studies and CFD Simulations
, Ph.D. Dissertation Sharif University of Technology ; Bastani, Dariush (Supervisor) ; Miller, Reinhard (Co-Advisor) ; Yar Javadi, Ali (Co-Advisor)
Abstract
Understanding the hydrodynamic and physical chemistry basis of surface phenomena is very important for many branches of basic science like Chemical Engineering, Mechanics, Space Engineering, and Material Engineering in the level of fundamental studies and applications. In addition to the common technologies, the role of surface phenomena in novel technologies is also very essential. For example, nanotechnology, chemical or physical sensors, or micro electrical systems in which surface phenomena is playing a main role. Therefore, understanding the basis of surface science is very important for any development in many industrial and fundamental studies. The main topic of this thesis which is a...
Non-equilibrium Interfacial Properties of Dynamic Interfaces; Experimental and Computational Fluid Dynamic Investigations
, Ph.D. Dissertation Sharif University of Technology ; Bastani, Daruoosh (Supervisor) ; Miller, Reinhard (Supervisor) ; Javadi, Aliyar (Supervisor)
Abstract
Surface phenomena and dynamic Interfacial properties play an important role in gas- liquid and liquid-liquid multiphase process from various industrial applications to understand fundamental phenomena. However, there is no experimental equipment and efficient methods for quantitative and detail investigation of interfacial properties under fast and non-equilibrium dynamic condition due to mobility and refreshing of interface (such as rising bubble). Also existing models accompanied with a lot of simplifications which is not yet validated with a proper experimental data. In presented thesis work for the first time, quantitative study of dynamic adsorption layer in multiphase systems and more...
High frequency oscillatory flow in micro channels
, Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Vol. 460 , 2014 , pp. 355-360 ; ISSN: 09277757 ; Javadi, A ; Bastani, D ; Miller, R ; Sharif University of Technology
2014
Abstract
This paper deals with computational and experimental studies on the oscillatory flow at high frequencies up to 100. Hz performed with the Oscillating Drop and Bubble Analyzer (ODBA) setup based on the capillary pressure technique. The CFD results are validated considering pressure amplitude experimental data. The simulated results of phase shift between the generated oscillatory flow and the consequent pressure amplitudes show also good agreement with the experimental data. In absence of any compressibility and viscoelasticity effects and assumptions, a complex velocity field during oscillation is the main reason for the observation of a phase shift. The results of velocity profiles at the...
Interfacial instability of growing drop: experimental study and conceptual analysis
, Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Volume 347, Issue 1-3 , 2009 , Pages 167-174 ; 09277757 (ISSN) ; Bastani, D ; Kragel, J ; Miller, R ; Sharif University of Technology
Elsevier
2009
Abstract
Capillary pressure experiments were performed at the water/hexane interface including adsorption and mass exchange of hexanol under different conditions. The results from growing drop experiments show that instabilities due to Marangoni convection not only depend on the same parameters as have been reported for quasi-static interfaces, such as direction of mass transfer, distribution coefficient and ratio of diffusion coefficients, but also on the experimental conditions such as dispersed phase flow rate, capillary tip size, size of growing drop and its lifetime. Based on a new flow expansion model for mass transfer, a new approach is presented for data analysis, which includes the various...
Influence of surface-modified nanoparticles on the hydrodynamics of rising bubbles
, Article Chemical Engineering and Technology ; Volume 44, Issue 3 , 2021 , Pages 513-520 ; 09307516 (ISSN) ; Bastani, D ; Lotfi, M ; Miller, R ; Sharif University of Technology
Wiley-VCH Verlag
2021
Abstract
Local velocities of bubbles rising in four different nanosilica solutions were investigated experimentally. Also, the density, viscosity, and surface tension of fumed nanosilica and modified nanosilica solutions were measured. Heat treatment and chemical functionalization were used to modify the properties of silica nanoparticles. It was found that the addition of nanosilica affected the hydrodynamics of the rising bubble by increasing the drag friction at the interface. However, environmentally responsive nanosilica particles behaved like surfactant molecules, due to the interfacial activity of hydrophilic and hydrophobic chains. Silica nanoparticles coated with both hydrophilic and...
Droplet dynamics in rotating flows
, Article Advances in Colloid and Interface Science ; Volume 236 , 2016 , Pages 63-82 ; 00018686 (ISSN) ; Javadi, K ; Taeibi Rahni, M ; Miller, R ; Sharif University of Technology
Elsevier B.V
2016
Abstract
This paper deals with investigations of droplet dynamics in rotating flows. In many previous studies droplet dynamics was analyzed in simple unidirectional flows. To fill this gap, the focus of this study is an overview on investigations of droplet dynamics in a complex rotating flow. A Lattice Boltzmann Method with high potential in simulation of two-phase unsteady flows is applied to simulate the physics of the problem in a lid-driven cavity. In spite of its simple geometry, there is a complex rotating flow field containing different vortices and shear regions. The Reynolds number based on the cavity length scale and the upper wall velocity, ReL, is considered to be 1000. We discuss here...
Bubble in flow field: A new experimental protocol for investigating dynamic adsorption layers by using capillary pressure tensiometry
, Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Vol. 460, issue , 2014 , p. 369-376 ; Bastani, D ; Ulaganathan, V ; Miller, R ; Javadi, A ; Sharif University of Technology
2014
Abstract
For many years the model of a dynamic adsorption layer (DAL) is well established as explanation for the behavior of rising bubbles in surfactant solutions. This model explains the velocity profile and the evolution of the shape of a rising bubble based on the hypothesis of the balance between the drag force and the structure of the adsorbed layer governed by Marangoni convection. However, direct measurements of interfacial properties of the bubble during rising are a real challenge. Here we present a new experimental protocol called "bubble in flow field" suitable for direct measurements of dynamic interfacial properties of a bubble surface using the capillary pressure tensiometry under...
A novel technique to semi-quantitatively study the stability of emulsions and the kinetics of the coalescence under different dynamic conditions
, Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Vol. 460 , 2014 , pp. 327-332 ; ISSN: 09277757 ; Orr, R ; Bastani, D ; Javadi, A ; Lotfi, M ; Miller, R ; Sharif University of Technology
2014
Abstract
The kinetics of coalescence is studied experimentally using a new technique for tracking the process in the bulk phase. For this aim, aqueous solutions of KSCN (colorless) and FeCl3 (light yellow) are used to make individual W/O emulsions. Any coalescence occurred between drops containing KSCN solution and those containing FeCl3 solution would combine these solutions. This leads to a reddish brown solution due to the formation of iron(III)thiocyanate. The intensity change of this red color with time represents the dynamics of coalescence occurring between drops of different emulsified aqueous droplets. The detector response to any changes in the system is recorded as a function of time. In...
Rheology of interfacial layers
, Article Current Opinion in Colloid and Interface Science ; Vol. 19, issue. 6 , 2014 , pp. 514-519 ; ISSN: 13590294 ; Lotfi, M ; Kragel, J ; Javadi, A ; Bastani, D ; Miller, R ; Sharif University of Technology
2014
Abstract
Dilational and shear viscoelasticities are important properties of interfacial layers. These quantities are particularly relevant in all systems which contain a huge internal interfacial area such as foams and emulsions. Therefore, also the 3D rheological behavior of foams or emulsions studied by respective methods is superimposed by the 2D interfacial rheology.We report on recent developments in dilational and shear rheology from an experimental point of view as well as discuss the state of the art of the underlying theories. Examples of most relevant experiments are also presented and discussed. Although not yet extensively investigated, the links between bulk rheology of foams and...
Dynamics of rear stagnant cap formation at the surface of rising bubbles in surfactant solutions at large reynolds and marangoni numbers and for slow sorption kinetics
, Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Volume 492 , 2016 , Pages 127-137 ; 09277757 (ISSN) ; Lotfi, M ; Kovalchuk, V. I ; Bastani, D ; Miller, R ; Sharif University of Technology
Elsevier
2016
Abstract
In spite of the high level in the theory of steady rear stagnant caps (RSC) and its influence on steady rising, its practical application is mostly impossible because the coefficients for the adsorption and desorption rates are separately unknown. The determination of ka and kd separately is an actual task for the adsorption dynamics as whole. While steady RSC and steady rising retardation by surfactants are described in literature in details, only few papers are devoted to the modeling of the decelerated rising. Moreover, steady rising depends on the ratio ka/kd and its investigation is not helpful for the determination of kd. In contrast a possibility to determine kd (or ka independently)...
Flow physics exploration of surface tension driven flows
, Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Volume 518 , 2017 , Pages 30-45 ; 09277757 (ISSN) ; Moezzi Rafie, H ; Goodarzi Ardakani, V ; Javadi, A ; Miller, R ; Sharif University of Technology
2017
Abstract
Surface tension driven passive micro-pumping relies mainly on the surface tension properties. To have control over surface tension driven passive micro-pumps (STD-PMPs), it is essential to understand the physical background of the fluid flow in these pumps. Hence, the purpose of this work is to give an exploration of the flow physics of a STD-PMP. In this regard, computer simulation is used to give detailed information about the flow pattern and physical phenomena at different conditions. To this end, a droplet of water, with a specified diameter, is placed onto an entry port connected to another droplet at the exit port via a microchannel. The results indicate that the pumping process, in...
Studies of the rate of water evaporation through adsorption layers using drop shape analysis tensiometry
, Article Journal of Colloid and Interface Science ; Volume 308, Issue 1 , 2007 , Pages 249-253 ; 00219797 (ISSN) ; Makievski, A. V ; Krägel, J ; Javadi, A ; Miller, R ; Sharif University of Technology
2007
Abstract
With modified measuring procedure and measuring cell design in the drop profile tensiometer PAT, it became possible to study the rate of water evaporation through adsorbed or spread surface layers. This method was employed to measure the rate of water evaporation from drops covered by adsorbed layers of some proteins and surfactants, in particular n-dodecanol. It was shown that the formation of dense (double or condensed) adsorbed layers of protein and the formation of 2D-condensed n-dodecanol layer decrease the water evaporation rate by 20-25% as compared with pure water. At the same time, the adsorbed layers of ordinary surfactants (sodium dodecyl sulfate and nonionic ethoxylated...
Bacteria cell hydrophobicity and interfacial properties relationships: A new MEOR approach
, Article Colloids and Interfaces ; Volume 5, Issue 4 , 2021 ; 25045377 (ISSN) ; Javadi, A ; Jahanbani Veshareh, M ; Ayatollahi, S ; Miller, R ; Sharif University of Technology
MDPI
2021
Abstract
For microbial enhanced oil recovery (MEOR), different mechanisms have been introduced. In some of these papers, the phenomena and mechanisms related to biosurfactants produced by certain microorganisms were discussed, while others studied the direct impacts of the properties of microorganisms on the related mechanisms. However, there are only very few papers dealing with the direct impacts of microorganisms on interfacial properties. In the present work, the interfacial properties of three bacteria MJ02 (Bacillus Subtilis type), MJ03 (Pseudomonas Aeruginosa type), and RAG1 (Acinetobacter Calcoaceticus type) with the hydrophobicity factors 2, 34, and 79% were studied, along with their direct...
Adsorption of proteins at the solution/air interface influenced by added nonionic surfactants at very low concentrations for both components. 3. dilational surface rheology
, Article Journal of Physical Chemistry B ; Volume 119, Issue 9 , January , 2015 , Pages 3768-3775 ; 15206106 (ISSN) ; Aksenenko, E. V ; Lylyk, S. V ; Lotfi, M ; Miller, R ; Sharif University of Technology
2015
Abstract
The influence of the addition of the nonionic surfactants C12 DMPO, C14 DMPO, C10 OH, and C10 EO5 at concentrations between 10-5 and 10-1 mmol/L to solutions of β-casein (BCS) and β-lactoglobulin (BLG) at a fixed concentration of 10-5 mmol/L on the dilational surface rheology is studied. A maximum in the viscoelasticity modulus |E| occurs at very low surfactant concentrations (10-4 to 10-3 mmol/L) for mixtures of BCS with C12 DMPO and C14 DMPO and for mixtures of BLG with C10 EO5 , while for mixture of BCS with C10 EO5 the value of |E| only slightly increased. The |E| values...
Applicability of lattice Boltzmann method in simulation of drops and bubbles formation and transport
, Article AIP Conference Proceedings, 22 September 2014 through 28 September 2014 ; Volume 1648 , 2015 ; 0094243X (ISSN) ; 9780735412873 (ISBN) ; Alizadeh, M ; Haghshenas, M ; Salimi, H ; Najafi, M ; Miller, R ; Sharif University of Technology
2015
Abstract
Multiphase flows appear in many scientific and engineering applications. On the other hand, there has been a tremendous experimental and numerical investigation trying to understand complex fluid-fluid interfaces better. However, conventional CFD have certain limitations in complicated situations. Fortunately in the past two decades, new approaches, namely SPH and LBM (sometimes called meshless methods) have been developed. Since they are mesoscopic, they have been able to perform much better than conventional CFD. Especially, LBM is becoming more and more popular and has already been divided to many branches
Influence of new superhydrophobic micro-structures on delaying ice formation
, Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Volume 595 , 2020 ; Taeibi Rahni, M ; Javadi, K ; Davoudian, S. H ; Miller, R ; Sharif University of Technology
Elsevier B.V
2020
Abstract
Drop motion on different types of new proposed micro-structure surfaces has been numerically investigated to find the optimum structure in view point of ice formation delaying. The droplet automatically moves on the inclined surfaces due to gravity forces. To validate the numerical algorithm, three different bench mark problems have been considered. The results indicate that the present algorithm is trustable for the presented numerical simulations. Then the validated numerical approach has been used to simulate droplet motion on nine proposed superhydrophobic surfaces in the same conditions. Comparison the drop motion on different micro-structure surfaces at different time indicate that...
Adsorption of proteins at the solution/air interface influenced by added non-ionic surfactants at very low concentrations for both components. 1. Dodecyl dimethyl phospine oxide
, Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Volume 475, Issue 1 , June , 2015 , Pages 62-68 ; 09277757 (ISSN) ; Javadi, A ; Lylyk, S. V ; Bastani, D ; Fainerman, V. B ; Miller, R ; Sharif University of Technology
2015
Abstract
The adsorption of proteins at liquid interfaces happens at rather low bulk concentrations due to their rather high surface activity. In contrast typical surfactants start to decrease the surface tension at bulk concentration in the range of mmol/l and reach a minimum value at about two or three orders of magnitude higher concentration. The two proteins studied here, β-lactoglobulin and β-casein, adsorb already remarkably at much lower concentrations, i.e. less than 1. μmol/l. When smallest amounts of a non-ionic surfactant are added to low concentrated protein solutions, changes in the surface tension are observed which cannot be explained by the existing theoretical models. An agreement...
Mixed protein-surfactant adsorption layers formed in a sequential and simultaneous way at water-air and water-oil interfaces
, Article Soft Matter ; Volume 8, Issue 22 , 2012 , Pages 6057-6065 ; 1744683X (ISSN) ; Kotsmar, C ; Ferri, J. K ; Javadi, A ; Karbaschi, M ; Krägel, J ; Wüstneck, R ; Miller, R ; Sharif University of Technology
2012
Abstract
Mixed protein-surfactant adsorption layers can be built up in two different ways. The classical way is when all components adsorb simultaneously from a mixed solution. Alternatively, the components adsorb one after another, i.e. in a sequential way. In the present work, the formation of such surface layers has been studied with the random coil protein β-casein in the presence of added anionic surfactant SDS and compared for two different interfaces: the water-air (W-A) and water-hexane (W-H) interfaces. The used experimental technique is a drop profile analysis tensiometer PAT-1 specially equipped with a coaxial double capillary for drop volume exchange during the experiments. The results...
Dynamics of Rear Stagnant Cap formation at the surface of spherical bubbles rising in surfactant solutions at large Reynolds numbers under conditions of small Marangoni number and slow sorption kinetics
, Article Advances in Colloid and Interface Science ; Volume 222 , 2015 , Pages 260-274 ; 00018686 (ISSN) ; Kovalchuk, V. I ; Gochev, G. G ; Lotfi, M ; Krzan, M ; Malysa, K ; Miller, R ; Sharif University of Technology
Elsevier
2015
Abstract
On the surface of bubbles rising in a surfactant solution the adsorption process proceeds and leads to the formation of a so called Rear Stagnant Cap (RSC). The larger this RSC is the stronger is the retardation of the rising velocity. The theory of a steady RSC and steady retarded rising velocity, which sets in after a transient stage, has been generally accepted. However, a non-steady process of bubble rising starting from the initial zero velocity represents an important portion of the trajectory of rising, characterized by a local velocity profile (LVP). As there is no theory of RSC growth for large Reynolds numbers Re « 1 so far, the interpretation of LVPs measured in this regime was...
Marangoni instabilities for convective mobile interfaces during drop exchange: Experimental study and CFD simulation
, Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Vol. 441, issue , 2014 , pp. 846-854 ; ISSN: 09277757 ; Karbaschi, M ; Bastani, D ; Ferri, J. K ; Kovalchuk, V. I ; Kovalchuk, N. M ; Javadi, K ; Miller, R ; Sharif University of Technology
2014
Abstract
The inflow pattern of liquid into a droplet is studied experimentally using a surface active dye and compared with results of CFD simulations. The results show visual agreement between experiments and simulations. The CFD simulations show also good agreement with the surface tension measured by drop profile analysis tensiometry (PAT). The inflow of the surfactant induces a Marangoni instability caused by the local arrival of the surfactant at the drop surface. The onset of this Marangoni instability observed experimentally has a delay of about 10. s when compared with the simulation results. Different scenarios are discussed, including a boundary layer barrier, a kinetic-controlled...