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45
Animation of bubbles in liquid
- Comput. Graph. Forum (Eurographics Proc
, 2003
"... We present a new fluid animation technique in which liquid and gas interact with each other, using the example of bubbles rising in water. In contrast to previous studies which only focused on one fluid, our system considers both the liquid and the gas simultaneously. In addition to the flowing moti ..."
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Cited by 48 (2 self)
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We present a new fluid animation technique in which liquid and gas interact with each other, using the example of bubbles rising in water. In contrast to previous studies which only focused on one fluid, our system considers both the liquid and the gas simultaneously. In addition to the flowing motion, the interactions between liquid and gas cause buoyancy, surface tension, deformation and movement of the bubbles. For the natural manipulation of topological changes and the removal of the numerical diffusion, we combine the volume-of-fluid method and the front-tracking method developed in the field of computational fluid dynamics. Our minimum-stress surface tension method enables this complementary combination. The interfaces are constructed using the marching cubes algorithm. Optical effects are rendered using vertex shader techniques.
Constructing material interfaces from data sets with volume-fraction information
- In Proceedings Visualization 2000
"... We present a new algorithm for material boundary interface reconstruction from data sets containing volume fractions. We transform the reconstruction problem to a problem that analyzes the dual data set, where each vertex in the dual mesh has an associated barycentric coordinate tuple that represent ..."
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Cited by 22 (10 self)
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We present a new algorithm for material boundary interface reconstruction from data sets containing volume fractions. We transform the reconstruction problem to a problem that analyzes the dual data set, where each vertex in the dual mesh has an associated barycentric coordinate tuple that represents the fraction of each material present. After constructing the dual tetrahedral mesh from the original mesh, we construct material boundaries by mapping a tetrahedron into barycentric space and calculating the intersections with Voronoi cells in barycentric space. These intersections are mapped back to the original physical space and triangulated to form the boundary surface approximation. This algorithm can be applied to any grid structure and can treat any number of materials per element/vertex.
Numerical simulation of bubble and droplet deformation by a level set approach with surface tension
, 2009
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Phase-Field Models for Multi-Component Fluid Flows
, 2012
"... In this paper, we review the recent development of phase-field models and their numerical methods for multi-component fluid flows with interfacial phenom-ena. The models consist of a Navier-Stokes system coupled with a multi-component Cahn-Hilliard system through a phase-field dependent surface te ..."
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Cited by 10 (0 self)
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In this paper, we review the recent development of phase-field models and their numerical methods for multi-component fluid flows with interfacial phenom-ena. The models consist of a Navier-Stokes system coupled with a multi-component Cahn-Hilliard system through a phase-field dependent surface tension force, variable density and viscosity, and the advection term. The classical infinitely thin boundary of separation between two immiscible fluids is replaced by a transition region of a small but finite width, across which the composition of the mixture changes continuously. A constant level set of the phase-field is used to capture the interface between two immis-cible fluids. Phase-field methods are capable of computing topological changes such as splitting and merging, and thus have been applied successfully to multi-component fluid flows involving large interface deformations. Practical applications are provided to illustrate the usefulness of using a phase-field method. Computational results of
NUMERICAL SIMULATION OF DROPLET-DEFORMATION BY A LEVEL SET APPROACH WITH SURFACE TENSION
"... Abstract. In this paper we present a three-dimensional Navier–Stokes solver for incompressible two-phase flow problems with surface tension and apply the proposed scheme to the simulation of droplet-deformation. Our approach employs a standard finite difference/finite volume discretization on unifor ..."
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Cited by 8 (2 self)
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Abstract. In this paper we present a three-dimensional Navier–Stokes solver for incompressible two-phase flow problems with surface tension and apply the proposed scheme to the simulation of droplet-deformation. Our approach employs a standard finite difference/finite volume discretization on uniform Cartesian staggered grids and uses Chorin’s projection approach. The free surface between the two fluid phases is tracked with a level set technique. Here, the interface conditions are implicitly incorporated into the momentum equations by the continuum surface force method. Surface tension is evaluated using a smoothed delta function and third order interpolation. The problem of mass conservation for the two phases is treated by a reinitialization of the level set function employing a regularized signum function and a global fixed point iteration. All convective terms are discretized by a WENO scheme of fifth order. Altogether, our approach exhibits a second order convergence away from the free surface. The discretization of surface tension requires a smoothing scheme near the free surface which leads to a first order convergence in the smoothing region. We discuss the details of the proposed numerical scheme and present the results of several numerical experiments concerning mass conservation, convergence of curvature and the application of our solver to the simulation of droplet-deformation due to a shear flow in three space dimensions.
A mesh-dependent model for applying dynamic contact angles to VOF simulations
- JOURNAL OF COMPUTATIONAL PHYSICS
, 2009
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A Monolithic Mass Tracking Formulation for Bubbles in Incompressible Flow
"... We devise a novel method for treating bubbles in incompressible flow that relies on the conservative advection of bubble mass and an associated equation of state in order to determine pressure boundary conditions inside each bubble. We show that executing this algorithm in a traditional manner leads ..."
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Cited by 4 (3 self)
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We devise a novel method for treating bubbles in incompressible flow that relies on the conservative advection of bubble mass and an associated equation of state in order to determine pressure boundary conditions inside each bubble. We show that executing this algorithm in a traditional manner leads to stability issues similar to those seen for partitioned methods for solid-fluid coupling. Therefore, we reformulate the problem monolithically. This is accomplished by first proposing a new fully monolithic approach to coupling incompressible flow to fully nonlinear compressible flow including the effects of shocks and rarefactions, and then subsequently making a number of simplifying assumptions on the air flow removing not only the nonlinearities but also the spatial variations of both the density and the pressure. The resulting algorithm is quite robust, has been shown to converge to known solutions for test problems, and has been shown to be quite effective on more realistic problems including those with multiple bubbles, merging and pinching, etc. Notably, this approach departs from a standard two-phase incompressible flow model where the air flow preserves its volume despite potentially large forces and pressure differentials in the surrounding incompressible fluid that should change its volume. Our bubbles readily change volume according to an isothermal equation of state. 1.
LARGE DROPLET IMPACT ON WATER LAYERS
"... The impact of large droplets onto an otherwise undisturbed layer of water is considered. The work, which is motivated primarily with regard to aircraft icing, is to try and help understand the role of splashing on the formation of ice on a wing, in particular for large droplets where splash appears ..."
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Cited by 4 (4 self)
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The impact of large droplets onto an otherwise undisturbed layer of water is considered. The work, which is motivated primarily with regard to aircraft icing, is to try and help understand the role of splashing on the formation of ice on a wing, in particular for large droplets where splash appears to have a significant effect. Analytical and numerical approaches are used to investigate a single droplet impact onto a water layer. The flow for small times after impact is determined analytically, for both direct and oblique impacts. The impact is also examined numerically using the volume of fluid (VOF) method. At small times there are promising comparisons between the numerical results, the analytical solution and experimental work capturing the ejector sheet. At larger times there is qualitative agreement with experiments and related simulations. Various cases are considered, varying the droplet size to layer depth ratio, including surface roughness, droplet distortion and air effects. The amount of fluid splashed by such an impact is examined and is found to increase with droplet size and to be significantly influenced by surface roughness. The makeup of the splash is also considered, tracking the incoming fluid, and the splash is found to consist mostly of fluid originating in the layer.
A Mass-Conserving Level-Set (MCLS) Method for Modeling of Multi-Phase Flows
, 2003
"... The Mass-Conserving Level-Set (MCLS) method is proposed to model multi-phase ows. The aim is to model high density-ratio
ows with com-plex interface topologies, such as mixtures of bubbles and droplets. As-pects which are taken into account are: a sharp front (density changes rapidly), arbitrary sh ..."
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Cited by 3 (0 self)
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The Mass-Conserving Level-Set (MCLS) method is proposed to model multi-phase ows. The aim is to model high density-ratio
ows with com-plex interface topologies, such as mixtures of bubbles and droplets. As-pects which are taken into account are: a sharp front (density changes rapidly), arbitrary shaped interfaces, surface tension, buoyancy and co-alescence of drops/bubbles. Attention is paid to mass-conservation and integrity of the interface. A survey of available computational methods is performed in [1]. The proposed computational method is a combination of Level-Set and Volume-of-Fluid methods. The
ow is computed with a pressure correction method with a Marker-and-Cell layout. Interface conditions are satised by means of the continuous surface force/stress (CSF/CSS) methodology and the GhostFluid method for incompressible
ows. The Level-Set method is an elegant method. The major disadvan-tage is that it is not rigorously mass-conserving. This means that ad-ditional eort is necessary to conserve mass. The MCLS method intro-duces a Volume-of-Fluid function, which is advected without the neces-sity to reconstruct the interface. There is a strong relationship between the Volume-of-Fluid function and the Level-Set function. In the spirit of the Level-Set methodology, the advection of the VOF-function is, un-like other VOF methods, purely implicit at every time. This makes the method straightforward to apply to arbitrarily shaped interfaces, which may collide and break up. 1
