Extraction and tracking of multi-scaled vortices from a homogeneous isotropic turbulent field

Kareem, Waleed Abdel; Izawa, Seiichiro; Xiong, Ao Kui; Fukunishi, Yu

doi:10.1080/14685240600990274

Cited by 7 publications

(5 citation statements)

References 13 publications

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“…They showed that vorticity vectors of a certain scale field tended to align with the first eigenvector of the rate-of-strain tensor of the velocity field of larger scales, and they concluded that the vortices were stretched by these larger-scale velocity fields. Kareem et al (2007) investigated the vortex motion of various scales in isotropic turbulence using Fourier lowpass filters. They visualized vortical structures of various scales and tracked their motion in time; they showed that vortices were stretched regardless of their scales.…”

Section: Introductionmentioning

confidence: 99%

Hierarchical vortical structures extracted from turbulent fields

et al. 2019

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The fourth and fifth sentences in the caption of figure 3 on page 6 should read: 'When λ 2 <0, positionc at which the value of Q reaches a local maximum is calculated in the plane normal to e 1 . When c is within the half grid distance from X, the eigenvector x with the largest eigenvalue of the Hessian of Q at c is calculated. The obtained point, c, and vector, x, are considered to be the position and direction of the vortex axis.'The next sentence of equation (7) on page 6 should read: 'When the obtained point, c, is within a half grid distance from the grid point,, the eigenvector x with the largest eigenvalue of the Hessian of Q at c is calculated.'

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Section: Introductionmentioning

confidence: 99%

Hierarchical vortical structures extracted from turbulent fields

et al. 2019

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“…For a given time instant, the process of extraction of the coherent structures includes the following steps (Kareem et al , 2007): Calculate Q n values for the entire domain. Set up a threshold value Q th . The selection of the threshold value affects the visualization results.…”

Section: Methodsmentioning

confidence: 99%

“…If the structure is larger than or equal to V cr , all Q n values of the structure are recorded. Usually, the volume criterion V cr is set as 4% of the maximum volume of the identified coherent structures V cr = 4% V max (Kareem et al , 2007).…”

Section: Methodsmentioning

confidence: 99%

Liquid drop breakup in homogeneous isotropic turbulence

Zhong

Komrakova

2019

HFF

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Purpose This paper aims to demonstrate the capabilities of a diffuse interface free energy lattice Boltzmann method to perform direct numerical simulations of liquid–liquid dispersions in a well-controlled turbulent environment. The goal of this research study is to develop numerical techniques that can visualize and quantify drop interaction with the turbulent vortices. The obtained information will be used for the development of sub-models of drop breakup for multi-scale simulations. Design/methodology/approach A pure binary liquid system is considered that is subject to fully developed statistically stationary turbulent flow field in a cubic fully periodic box with the edge size of 300 lattice units. Three turbulent flow fields with varying energy input are examined and their coherent structures are visualized using a normalized Q-criterion. The evolution of the liquid–liquid interface is tracked as a function of time. The detailed explanation of the numerical method is provided with a highlight on a choice of the numerical parameters. Findings Drop breakup mechanisms differ depending on energy input. Drops break due to interaction with the vortices. Quantification of turbulent structures shows that the size of vortices increases with the decrease of energy input. Drop interacts simultaneously with multiple vortices of the size comparable to or smaller than the drop size. Vortices of the size smaller than the drop size disturb drop interface and pinch off the satellites. Vortices of the size comparable to the drop size tend to elongate the drop and tear it apart producing daughter drops and satellites. Addition of the second phase enhances turbulent dissipation at the high wavenumbers. To obtain physically realistic two-phase energy spectra, the multiple-relaxation-time collision operator should be used. Originality/value Detailed information of drop breakup in the turbulent flow field is crucial for the development of drop breakup sub-models that are necessary for multi-scale numerical simulations. The improvement of numerical methods that can provide these data and produce reliable results is important. This work made one step towards a better understanding of how drops interact with the turbulent vortices.

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“…Most of these studies concern decaying homogeneous isotropic turbulence [3]. To our knowledge, few studies have investigated forced homogeneous turbulence [4,5] and Cate et al [6] used a spectral forcing with LBM, where they used the Fourier transformation for the forcing term in each time step. This paper is organized as follows.…”

Section: Introductionmentioning

confidence: 99%

Lattice Boltzmann simulations of homogeneous isotropic turbulence

Kareem

Izawa

Xiong

et al. 2009

Computers & Mathematics with Applications

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a b s t r a c tThe Lattice Boltzmann Method (LBM) with a forcing scheme is used to simulate homogeneous isotropic turbulence, and the resolutions of 128 3 and 256 3 are compared. Two models, D3Q 15 and D3Q 19, are used in the investigation. Results demonstrate that the Lattice Boltzmann Method can capture important features of turbulence such as the vortex-like tubes and the Kolmogorov −5/3 power spectrum. Visualization of the elongated vortices using the high rotational identification method, Q , is also presented. For 256 3 , a longer range of the Kolmogorov −5/3 slope can be observed than in the case of 128 3 grid points. As the resolution increases, the turbulence characteristics of the flow are found to become similar to those obtained in studies by the spectral method regardless of which model is used.

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Extraction and tracking of multi-scaled vortices from a homogeneous isotropic turbulent field

Cited by 7 publications

References 13 publications

Hierarchical vortical structures extracted from turbulent fields

Hierarchical vortical structures extracted from turbulent fields

Liquid drop breakup in homogeneous isotropic turbulence

Lattice Boltzmann simulations of homogeneous isotropic turbulence

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