A hybrid interface method for three-dimensional multiphase flows based on front tracking and level set techniques

Shin, Seungwon,Juric, Damir John Wiley Sons, Ltd. 2009 International journal for numerical methods in flu Vol.60 No.7

<P>Successful interface methods for multiphase flows need to be designed to operate well in the opposite extremes of strongly surface tension-dominant flows on the one hand and strongly deforming flows on the other. To this end, recent advances in direct numerical simulation of multiphase flows have involved the hybridization of popular methods. One hybrid approach developed by the authors is the level contour reconstruction method (LCRM), which combines the characteristics of both the front tracking and the level set method. It was designed specifically for general 3D multiphase flow problems where very dynamic and deformable interfaces interact and where accuracy, reliability, and simplicity are essential features. In this paper, we carry the hybridization of the LCRM with the level set technique to a further level in that the explicit calculation of a distance function is introduced and plays a crucial role in the interface reconstruction procedure as well as in the calculation of the surface tension force. An accurate method of computing the distance function directly from the tracked interface is presented whereby a vector distance function is found, i.e. the minimum distance to the interface as well as the corresponding minimum distance point location on the interface itself. This information allows us to calculate a compact curvature field for the computation of the surface tension force, which decreases the level of parasitic currents to a negligible level. Various benchmark test cases to demonstrate the accuracy of the new schemes compared with other existing methods are provided. Copyright © 2008 John Wiley & Sons, Ltd.</P>

Simulation of droplet impact on a solid surface using the level contour reconstruction method

신승원,Damir Juric 대한기계학회 2009 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.23 No.9

We simulate the three-dimensional impact of a droplet onto a solid surface using the level contour reconstruction method (LCRM). A Navier-slip dynamic contact line model is implemented in this method and contact angle hysteresis is accounted for by fixing the contact angle limits to prescribed advancing or receding angles. Computation of a distance function directly from the tracked interface enables a straightforward implementation of the contact line dynamic model in the LCRM. More general and sophisticated contact line models are readily applicable in this front tracking approach with few modifications, since complete knowledge of the geometrical information of the interface in the vicinity of the wall contact region is available. Several validation tests are performed including 2D planar droplet, 2D axisymmetric droplet, and full three-dimensional droplet splashing problems. The results show good agreement compared with existing numerical and experimental solutions.

High Order Level Contour Reconstruction Method

Seungwon Shin,Damir Juric 대한기계학회 2007 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.21 No.2

Complex interfacial physics arising from geometric curvature associated with surface tension as well as phase transformation make it a formidable task to design an accurate, reliable, and yet simple method for direct computation of multiphase flows. Hybrid methods mixing conventional, Volume-of-Fluid, Level Set, Phase Field, and Front Tracking methods have recently become popular in an attempt to overcome the shortcomings of each method alone. We developed the Level Contour Reconstruction Method (LCRM) as part of a hybrid method for treating the complex interface geometry associated with general three-dimensional multiphase flows. The main idea in that work focused on a simple and robust algorithm especially suited for dynamic interfaces in the three-dimensional case by combining characteristics of both Front Tracking and Level Set methods. In this article we describe a modification to the LCRM which introduces a high order interpolation kernel during the course of the interface reconstruction along with a new hybrid surface tension formulation. With this we can essentially eliminate any mass redistribution between regions of differing curvature and reconstruct the interface accurately and smoothly. The improvement with high order reconstruction is also noticeable vis a vis spurious currents which are further decreased by two orders of magnitude over the previous linear reconstruction method. Moreover, there is no disturbance concurrent with reconstruction and the solution fidelity is not influenced by the reconstruction time step. This High Order Level Contour Reconstruction Method retains the simplicity of the original LCRM and avoids complicated interface smoothing procedures.

Customer engagement: Developing an innovative research that has scholarly impact

Roderick J. Brodie,Biljana Juric 한국마케팅과학회 2018 마케팅과학연구 Vol.28 No.3

This essay outlines the development of a stream of research about customer engagement that is having a substantial scholarly impact. We explore the conditions to achieve this success which includes the critical role of the theorizing process. The theorizing process is the core to crafting two seminal contributions. Implications for achieving innovative research that has a scholarly impact concludes the essay.

NEGATIVE ACTOR ENGAGEMENT IN STUDENT LEARNING SYSTEM: CONCEPTUALISATION, SCALE DEVELOPMENT AND VALIDATION

Loic Pengtao Li,Biljana Juric,Roderick Brodie 글로벌지식마케팅경영학회 2018 Global Marketing Conference Vol.2018 No.07

A predominantly positive view is shown in engagement literature in terms of positive actor engagement (PNE) expressions and outcomes. However, business practices indicate that the understanding of actors being negatively engaged is important. Yet a few studies in marketing, which attempt to conceptualise negative actor engagement (NAE), do not have a consensus as for whether NE and PE are reciprocal or NE is a distinct construct with a different nomological network and process. The purpose of this study is to conceptualise and operationalise NAE. Built on Li et al.’s (2018) conceptualisation of actor engagement valence, this paper follows Churchill’s (1979) methods of scale development and operationalises the construct of NAE. By developing and validating a NAE scale in specific online learning servcie platforms, we address this identified literature gap. Specifically, this study derives four NAE dimensions, including annoyance, anxiety, futitlity and failed expectation, which we proceed to validate within a nomological net of conceptual relationships in relation to the engagement behaviours (learning, sharing and endorsing). We conclude with an overview of key managerial and scholarly implications arising from this research. This marks the first study in the marketing discipline to operationalise NAE.

Direct simulation of multiphase flows with modeling of dynamic interface contact angle

Shin, Seungwon,Chergui, Jalel,Juric, Damir Springer-Verlag 2018 Theoretical and computational fluid dynamics Vol.32 No.5

A solver for massively parallel direct numerical simulation of three-dimensional multiphase flows

Shin, S.,Chergui, J.,Juric, D. Springer Science + Business Media 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.4

<P>We present a new solver for massively parallel simulations of fully three-dimensional multiphase flows. The solver runs on a variety of computer architectures from laptops to supercomputers and on 262144 threads or more (limited only by the availability to us of more threads). The code is wholly written by the authors in Fortran 2008 and uses a domain decomposition strategy for parallelization with MPI. The fluid interface solver is based on a parallel implementation of the LCRM hybrid front tracking/level set method designed to handle highly deforming interfaces with complex topology changes. We discuss the implementation of this interface method and its particular suitability to distributed processing where all operations are carried out locally on distributed subdomains. We have developed parallel GMRES and Multigrid iterative solvers suited to the linear systems arising from the implicit solution of the fluid velocities and pressure in the presence of strong density and viscosity discontinuities across fluid phases. Particular attention is drawn to the details and performance of the parallel Multigrid solver. The code includes modules for flow interaction with immersed solid objects, contact line dynamics, species and thermal transport with phase change. Here, however, we focus on the simulation of the canonical problem of drop splash onto a liquid film and report on the parallel performance of the code on varying numbers of threads. The 3D simulations were run on mesh resolutions up to 1024(3) with results at the higher resolutions showing the fine details and features of droplet ejection, crown formation and rim instability observed under similar experimental conditions.</P>

A hybrid interface tracking – level set technique for multiphase flow with soluble surfactant

Shin, Seungwon,Chergui, Jalel,Juric, Damir,Kahouadji, Lyes,Matar, Omar K.,Craster, Richard V. Elsevier 2018 Journal of computational physics Vol.359 No.-

<P><B>Abstract</B></P> <P>A formulation for soluble surfactant transport in multiphase flows recently presented by Muradoglu and Tryggvason (JCP 274 (2014) 737–757) is adapted to the context of the Level Contour Reconstruction Method, LCRM, (Shin et al. IJNMF 60 (2009) 753–778, ) which is a hybrid method that combines the advantages of the Front-tracking and Level Set methods. Particularly close attention is paid to the formulation and numerical implementation of the surface gradients of surfactant concentration and surface tension. Various benchmark tests are performed to demonstrate the accuracy of different elements of the algorithm. To verify surfactant mass conservation, values for surfactant diffusion along the interface are compared with the exact solution for the problem of uniform expansion of a sphere. The numerical implementation of the discontinuous boundary condition for the source term in the bulk concentration is compared with the approximate solution. Surface tension forces are tested for Marangoni drop translation. Our numerical results for drop deformation in simple shear are compared with experiments and results from previous simulations. All benchmarking tests compare well with existing data thus providing confidence that the adapted LCRM formulation for surfactant advection and diffusion is accurate and effective in three-dimensional multiphase flows with a structured mesh. We also demonstrate that this approach applies easily to massively parallel simulations.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Extension of the LCRM Front-tracking method (Shin et al. IJNMF 60 (2009) 753–778) to flows with surfactant. </LI> <LI> Following Muradoglu and Tryggvason (JCP 274 (2014) 737–757) surfactant transport is solved on the interface and in the bulk. </LI> <LI> Accuracy demonstrated for mass conservation, surface advection and diffusion, bulk transport and Marangoni stresses. </LI> <LI> Large scale parallel calculations of two-phase annular film flow in the counter-current flow regime. </LI> </UL> </P>

Hybridization of front tracking and level set for multiphase flow simulations: a machine learning approach

Ikroh Yoon,Jalel Chergui,Damir Juric,신승원 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.9

A machine learning (ML) based approach is proposed to hybridize two wellestablished methods for multiphase flow simulations: the front tracking (FT) and the level set (LS) methods. Based on the geometric information of the Lagrangian marker elements which represents the phase interface in FT simulations, the distance function field, which is the key feature for describing the interface in LS simulations, is predicted using an ML model. The trained ML model is implemented in our conventional numerical framework, and we finally demonstrate that the FT-based interface representation can easily and immediately be switched to an LS-based representation whenever needed during the simulation period.

Hysteretic Faraday waves

Pé,rinet, Nicolas,Falcó,n, Claudio,Chergui, Jalel,Juric, Damir,Shin, Seungwon American Physical Society 2016 Physical Review E Vol.93 No.6