Numerical Study of Bubble Rising Motion in a Vertical Wedge-Shaped Channel Based on a Modified Level Set Method

A numerical study of the initial stages of wave breaking processes in shallow water is presented. The waves considered are assumed to be generated by moving a piston in a two-dimensional channel, and may appear, for example, in the injection chamber of a high-pressure die casting machine under operating conditions far from the optimal. A numerical model based on a finite-difference discretization of the Navier-Stokes equations in a Cartesian grid and a second-order approximate projection method has been developed and used to carry out the simulations. The evolution of the free surface is described using a level set method, with a reinitialization procedure of the level set function which uses a local grid refinement near the free surface. The ability of different algorithms to improve mass conservation in the reinitialization step of the level set function has been tested in a time-reversed single vortex flow. The results for the breaking wave profiles show the flow characteristics after the impact of the first plunging jet onto the wave’s forward face and during the subsequent splash-up.

Download Full-text

Numerical study of droplet deformation in shear flow using a conservative level-set method

Chemical Engineering Science ◽

10.1016/j.ces.2019.06.014 ◽

2019 ◽

Vol 207 ◽

pp. 153-171 ◽

Cited By ~ 5

Author(s):

Ahmad Amani ◽

Néstor Balcázar ◽

Jesús Castro ◽

Assensi Oliva

Keyword(s):

Shear Flow ◽

Level Set Method ◽

Level Set ◽

Numerical Study ◽

Droplet Deformation ◽

Conservative Level Set

Download Full-text

A numerical study on the entry problem of an elastic body using a level set method and a monolithic formulation

Journal of Mechanical Science and Technology ◽

10.1007/s12206-012-0316-8 ◽

2012 ◽

Vol 26 (5) ◽

pp. 1341-1346 ◽

Cited By ~ 3

Author(s):

Hyoung Gwon Choi

Keyword(s):

Elastic Body ◽

Level Set Method ◽

Level Set ◽

Numerical Study ◽

Monolithic Formulation

Download Full-text

Analytical and level-set method based numerical study on oil–water smooth/wavy stratified-flow in an inclined plane-channel

International Journal of Multiphase Flow ◽

10.1016/j.ijmultiphaseflow.2011.08.015 ◽

2012 ◽

Vol 38 (1) ◽

pp. 99-117 ◽

Cited By ~ 18

Author(s):

Vinesh H. Gada ◽

Atul Sharma

Keyword(s):

Level Set Method ◽

Level Set ◽

Numerical Study ◽

Plane Channel ◽

Stratified Flow ◽

Inclined Plane ◽

Oil Water

Download Full-text

A numerical study of droplet splitting in branched T-shaped microchannel using the two-phase level-set method

Advances in Mechanical Engineering ◽

10.1177/16878140211045487 ◽

2021 ◽

Vol 13 (11) ◽

pp. 168781402110454

Author(s):

Mohammad Raad ◽

Sajad Rezazadeh ◽

Habib Jalili ◽

Davod Abbasinezhad Fallah

Keyword(s):

Pressure Gradient ◽

Level Set Method ◽

Level Set ◽

Numerical Study ◽

Immiscible Liquid ◽

Length Ratio ◽

Significant Feature ◽

Two Phase ◽

Droplet Splitting ◽

Passive Technique

Droplet splitting as a significant feature of droplet-based microfluidic systems has been widely employed in biotechnology, biomedical engineering, tissue engineering, and it has been preferred over continuous flow systems. In the present paper, two-dimensional numerical simulations have been done to examine the asymmetrical droplet splitting process. The two-phase level set method (LSM) has been predicted to analyze the mechanism of droplet formation and droplet splitting in immiscible liquid/liquid two-phase flow in the branched T-junction microchannel. Governing equations on flow field have been discretized and solved using finite element-based COMSOL Multiphysics software (version 5.3a). Obtained numerical results were validated by experimental data reported in the literature which show acceptable agreement. The model was developed to simulate the mechanism of droplet splitting at the branched T-junction microchannel. This study provides a passive technique to asymmetrically split up microdroplets at the downstream T-junctions. The results show that outlet branches’ pressure gradient affects the droplet splitting. Specifically, it has been shown that the splitting ratio increases by increasing the length ratio, and equal droplet splitting can be achieved where the ratio is LL/ Lu = 1. We have used two outlet branches having the same width but different lengths to create the required pressure gradient. As the length ratio of the outlet branches increases, the diameter ratio increases as well.

Download Full-text

Simulation of Rising Bubble With Conservative Level Set Method

Volume 2: Fora, Parts A and B ◽

10.1115/fedsm2007-37556 ◽

2007 ◽

Author(s):

Luka Sˇtrubelj ◽

Iztok Tiselj

Keyword(s):

Level Set Method ◽

Level Set ◽

Test Case ◽

Final Shape ◽

Spherical Bubble ◽

Rising Bubble ◽

Bubble Rising ◽

Bubble Rising Velocity ◽

Viscous Stresses ◽

Conservative Level Set

Conservative level set method, introduced by E. Olsson and G. Kreis in 2005 is discussed. The test case with rising bubble consists of spherical bubble of smaller density in stagnant liquid of higher density. Due to the buoyancy spherical bubble is rising up and changing its shape. After certain time the bubble reaches final velocity and final shape. An in-house code was used to perform the simulations. The final shape of the bubble was investigated and also build-up of the bubble rising velocity, starting from the rest exhibiting an overshoot before reaching its final asymptotic value. This test allows testing of numerical model which has to accurately take into account buoyancy, viscous stresses and surface tension effects.

Download Full-text

Direct Numerical Simulation of the First Stages of a Plunging Breaker Using a Level Set Method

Volume 1: Symposia, Parts A, B and C ◽

10.1115/fedsm2009-78362 ◽

2009 ◽

Author(s):

Pablo Go´mez ◽

Claudio Zanzi ◽

Julia´n Palacios ◽

Joaqui´n Lo´pez ◽

Julio Herna´ndez

Keyword(s):

Level Set Method ◽

Level Set ◽

Stokes Equations ◽

Numerical Study ◽

Local Level ◽

Wave Crest ◽

Small Scale ◽

Breaking Wave ◽

Mass Force ◽

The Impact

A numerical study of wave breaking in shallow water is presented. The jet formed at the wave crest and the subsequent splash-up phenomenon resulting from the impact of the jet on the liquid surface are analyzed. The wave is assumed to be generated by an accelerated piston in an open channel containing liquid. The two-dimensional, incompressible, unsteady Navier-Stokes equations are solved using a local level set method to treat the interface evolution [Go´mez et al., Int. J. Numer. Meth. Engng, 63, pp. 1478–1512, 2005], which permits to analyze the combined air-liquid flow. Viscous and capillary effects are retained. The level set transport and reinitialization equations are solved in a narrow band around the interface using an adaptive refined grid. Two different approaches are considered to take into account the relative movement between the piston and the end wall of the channel. The first one uses a fixed grid and introduces a mass force per unit mass equal to the piston acceleration, and the second one is based on using a moving grid, which is compressed as the piston moves forward, and an arbitrary Lagrangian-Eulerian method. The numerical results obtained for the evolution of the wave shape during the breaking process, particularly the evolution of the plunging jet, the air cavity and the complex flow resulting from the impact of the plunging jet, are compared with experimental visualization results obtained for a small-scale breaking wave, for which the breaking process is strongly influenced by surface tension. A good degree of agreement was observed between both types of results during the first stages of the breaking process.

Download Full-text