Tipstreaming of a drop in simple shear flow in the presence of surfactant

We have developed a multi-phase SPH method to simulate arbitrary interfaces containing surface active agents (surfactants) that locally change the properties of the interface, such the surface tension coefficient. Our method incorporates the effects of surface diffusion, transport of surfactant from/to the bulk phase to/from the interface and diffusion in the bulk phase. Neglecting transport mechanisms, we use this method to study the impact of insoluble surfactants on drop deformation and breakup in simple shear flow and present the results in a fluid dynamics video.Comment: Two videos are included for the Gallery of Fluid Motion of the APS DFD Meeting 201

A 2D hybrid method for interfacial transport of passive scalars

A hybrid Eulerian-Lagrangian method is proposed to simulate passive scalar transport on arbitrary shape interface. In this method, interface deformation is tracked by an Eulerian method while the transport of the passive scalar on the material interface is solved by a single-layer Lagrangian particle method. To avoid particle clustering, a novel remeshing approach is proposed. This remeshing method can resample particles, adjust the position of particles by a relaxation process, and transfer mass from pre-existing particles to resampled particles via a redistribution process, which preserves mass both globally and locally. Computational costs are controlled by an adaptive remeshing strategy. Accuracy is assessed by a series of test cases.Comment: 32 pages 1nd 14 figure

A fully coupled 3D transport model in SPH for multi-species reaction-diffusion systems

In this paper we present a fully generalized transport model for multiple species in complex two and three-dimensional geometries. Based on previous work [1] we have extended our interfacial reaction-diffusion model to handle arbitrary numbers of species allowing for coupled reaction models. Each species is tracked independently and we consider different physics of a species with respect to the bulk phases in contact. We use our SPH model to simulate the reaction-diffusion problem on a pore-scale level of a solid oxide fuel cell (SOFC) with special emphasize on the effect of surface diffusion

Simulating incompressible thin-film fluid with a Moving Eulerian-Lagrangian Particle method

In this thesis, we introduce a Moving Eulerian-Lagrangian Particle (MELP) method, a mesh-free method to simulate incompressible thin-film fluid systems: soap bubbles, bubble clusters, and foams. The realistic simulation of such systems depends upon the successful treatment of three aspects: (1) the soap film\u27s deformation due to the tendency to minimize the surface energy, giving rise to the bouncy characteristics of soap bubbles, (2) the tangential fluid flow on the thin film, causing the thickness to vary spatially, which in conjunction with thin-film interference creates evolving and highly sophisticated iridescent color patterns, (3) the topological changes due to collision, separation, and fragmentation, which may create partition surfaces and non-manifold junctions that spontaneously settle into honeycomb structures due to force balance. The interleaving complexities from all three fronts render the task of accurately and affordably simulating thin-film fluid an open problem for the Computational Physics and Computer Graphics community. The proposed MELP method tackles these multifaceted challenges by employing a novel, bi-layer particle structure: a sparse set of Eulerian particles for dynamic interface tracking and PDE solving, and a fine set of Lagrangian particles for material and momentum transport. Such a design provides crucially advantageous numerical traits compared to existing frameworks. Compared to mesh-based methods, MELP\u27s particle-based nature makes it topologically agnostic, which allows it to conveniently simulate topological changes such as bubble-cluster formation and thin-film rupture. Furthermore, these Lagrangian structures carry out fluid advection naturally, conserve mass by design, and track sub-grid flow details. Compared to existing particle methods, our bi-layer design improves drastically on the computational performance in terms of both stability and efficiency. The advantage of this design will manifest in a wide range of experiments, including dynamic foam formation, Rayleigh-Taylor instability, Newton Black Films, and bubble bursting, showing an increased level of flow detail, increased number of regions in bubble clusters, and increased flexibility to recreate multi-junction formation on-the-fly. Furthermore, we validate its physical correctness against a variety of analytical baselines, by successfully recovering the equilibrium dihedral and tetrahedral angles, the exponential thickness profile of drainage under gravity, the curvature of partition surfaces, and the minimum surface area of double-bubbles

Numerical simulation of pore-scale flow in chemical flooding process

AbstractChemical flooding is one of the effective technologies to increase oil recovery of petroleum reservoirs after water flooding. Above the scale of representative elementary volume (REV), phenomenological modeling and numerical simulations of chemical flooding have been reported in literatures, but the studies alike are rarely conducted at the pore-scale, at which the effects of physicochemical hydrodynamics are hardly resolved either by experimental observations or by traditional continuum-based simulations. In this paper, dissipative particle dynamics (DPD), one of mesoscopic fluid particle methods, is introduced to simulate the pore-scale flow in chemical flooding processes. The theoretical background, mathematical formulation and numerical approach of DPD are presented. The plane Poiseuille flow is used to illustrate the accuracy of the DPD simulation, and then the processes of polymer flooding through an oil-wet throat and a water-wet throat are studies, respectively. The selected parameters of those simulations are given in details. These preliminary results show the potential of this novel method for modeling the physicochemical hydrodynamics at the pore scale in the area of chemical enhanced oil recovery

Geophysics and Ocean Waves Studies

The book “Geophysics and Ocean Waves Studies” presents the collected chapters in two sections named “Geophysics” and “Ocean Waves Studies”. The first section, “Geophysics”, provides a thorough overview of using different geophysical methods including gravity, self-potential, and EM in exploration. Moreover, it shows the significance of rock physics properties and enhanced oil recovery phases during oil reservoir production. The second section, “Ocean Waves Studies”, is intended to provide the reader with a strong description of the latest developments in the physical and numerical description of wind-generated and long waves, including some new features discovered in the last few years. The section is organized with the aim to introduce the reader from offshore to nearshore phenomena including a description of wave dissipation and large-scale phenomena (i.e., storm surges and landslide-induced tsunamis). This book shall be of great interest to students, scientists, geologists, geophysicists, and the investment community

A general comparetive study in long rod penetration using corrective smoothed particle method

Corrective smoothed particle method (CSPM) has been used to study the dynamic behavior of targets with different materials; AL, ALN and AL-ALN FGM in long rod penetration of an AL projectile. A mixed strength model with sigmoid formulation has been used to describe both yielding and fracture phenomena in the FGM. The strength model includes the JC dynamic yield relation and JHB fracture model with a continuum damage description approach. An efficient renormalization in continuity density approach is used to improve the SPH approximation of boundary physical variables. This study shows that the CSPM method in combination with the proper strength model describing the FGM dynamic behavior, can predict the mixed plastic and brittle response of different materials in long rod penetration problems

Tropfendynamik in Wandnähe - Möglichkeiten und Limitierungen von grenzflächenauflösenden Simulationen = Drop dynamics near walls − achievements and limitations of interface-resolving simulations

Die Interaktion von Sprays mit einer Wand ist für zahlreiche technische Anwendungen von Bedeutung. Während sie bei der Sprühkühlung und -beschichtung Grundlage des Verfahrens ist, ist sie bei der direkten Kraftstoffeinspritzung in Verbrennungsmotoren und der Einspritzung von Wasser-Harnstoff-Lösung in das Abgasreinigungssystem von Dieselfahrzeugen unerwünscht und ihr Einfluss damit zu minimieren. In allen diesen Fällen stellt die Wechselwirkung eines Einzeltropfens mit der trockenen oder benetzten Wand den fundamentalen physikalischen Prozess dar, den es zu verstehen gilt, um die jeweilige technische Anwendung in dem gewünschten Sinne zu optimieren. Dies ist umso wichtiger, als neuartige Bearbeitungstechniken zunehmend die gezielte chemische und topologische Strukturierung von Oberflächen ermöglichen. Zur Generierung des notwendigen grundlegenden Verständnisses bieten sich in Ergänzung zu Experimenten insbesondere grenzflächenauflösende („direkte“) numerische Simulationen an. In der letzten Dekade wurden hierzu verschiedene leistungsfähige numerische Methoden entwickelt und zum Teil in quelloffenen Rechenprogrammen verfügbar gemacht. Der Vortrag stellt anhand ausgewählter Beispiele (mit Fokus auf der Kontinuumsbeschreibung) die derzeitigen Möglichkeiten und Limitierungen von grenzflächenauflösenden Simulationen zur Tropfen-Wechselwirkung mit trockenen und benetzten Wänden dar. Der für die Weiter-entwicklung hin zu zunehmend prädiktiven Simulationswerkzeugen notwendige Bedarf an verbesserten Modellen (z. B. hinsichtlich Kontaktlinienbewegung und -hysterese, Einbeziehung von Mischungseffekten, …) wird diskutiert

Application of dissipative particle dynamics to interfacial systems: Parameterization and scaling

Dissipative Particle Dynamics (DPD) is a stochastic particle model that is able to simulate larger systems over longer time scales than atomistic modeling approaches by including the concept of coarse-graining. Whether standard DPD can cover the whole mesoscale by changing the level of coarse-graining is still an open issue. A scaling scheme originally developed by Füchslin et al. (2009) was here applied to interfacial systems as one of the most successful uses of the classical DPD method. In particular, equilibrium properties such as the interfacial tension were analyzed at different levels of coarse-graining for planar oil–water interfaces with and without surfactant. A scaling factor for the interfacial tension was found due to the combined effect of the scaling scheme and the coarse-graining parameterization. Although the level of molecular description was largely decreased, promising results showed that it is possible to conserve the interfacial tension trend at increasing surfactant concentrations, remarkably reducing modeling complexity. The same approach was also employed to simulate a droplet configuration. Both planar and droplet conformations were maintained, showing that typical domain formations of multi-component systems can be performed in DPD by means of the scaling procedure. Therefore, we explored the possibility of describing oil–water and oil–water–surfactant systems in standard DPD using a scaling scheme with the aim of highlighting its advantages and limitations

Large Scale Dynamic Molecular Modelling of Metal Oxide Nanoparticles in Engineering and Biological Fluids

Nanoparticles (NP) offer great merits over controlling thermal, chemical and physical properties when compared to their micro-sized counterparts. The effectiveness of the dispersion of the NP is the key aspect of the applications in nanotechnology. The project studies the characterization and modification of functional NPs aided by the means of large scale molecular thermal dynamic computerized dispersing simulations, in the level of Nanoclusters (NC). Carrying out NP functionality characterisation in fluids can be enhanced, and analysed through computational simulation based on their interactions with fluidic media; in terms of thermo-mechanical, dynamic, physical, chemical and rheological properties. From the engineering perspective, effective characterizations of the nanofluids have also been carried out based on the particles sizes and particle-fluids Brownian motion (BM) theory. The study covered firstly, investigation of the pure CuO NP diffusion in water and hydrocarbon fluids, secondly, examination of the modified CuO NP diffusion in water. In both cases the studies were put under experiments and simulations for data collection and comparison. For simulation the COMPASS forcefield, smoothed particle hydrodynamic potential (SPH) and discrete particle dynamics potential (DPD) were implemented through the system. Excellent prediction of BM, Van der Waals interaction, electrostatic interaction and a number of force-fields in the system were exploited. The experimental results trend demonstrated high coherence with the simulation results. At first the diffusion coefficient was found to be 1.7e-8m2/s in the study of CuO NC in water based fluidic system. Secondly highly concurrent simulation results (i.e. data for viscosity and thermal conductivity) have been computed to experimental coherence. The viscosity trend of MD simulation and experimental results show a high level of convergence for temperatures between 303-323K. The simulated thermal conductivity of the water-CuO nanofluid was between 0.6—0.75W•m−1•K−1, showing a slight increase following a rise in temperature from 303 to 323 K. Moreover, the alkane-CuO nanofluid experimental and simulated work was also carried out, for analysing the thermo-physical quantities. The alkane-CuO nanofluid viscosity was found 0.9—2.7mpas and thermal conductivity is between 0.1—0.4W•m−1•K−1. Finally, the successful modification of the NPs on experimental and simulation platform has been analysed using different characterization variables. Experimental modification data has been quantified by using Fourier Transformation Infrared (FTIR) peak response, from particular ranges of interest i.e. 1667-1609cm-1 and 1668-1557cm-1. These FTIR peaks deduced Carboxylate attachment on the surface of NPs. Later, MD simulation was approached to mimic experimental setup of modification chemistry and similar agglomerations were observed as during experimental conditions. However, this approach has not been presented before; therefore this study has a significant impact on describing the agglomeration of modified NPs on simulation and experimental basis. Henceforth, the methodology established for metal oxide nanoparticle dispersion simulation is a novelty of this work