Multidimensional turbulence spectra - Statistical analysis of turbulent vortices
Artikel i vetenskaplig tidskrift, 2014

Strong nonlinear or very fast phenomena such as mixing, coalescence and breakup in chemical engineering processes, are not correctly described using average turbulence properties. Since these phenomena are modeled by the interaction of fluid particles with single or paired vortices, distribution of the properties of individual turbulent vortices should be studied and understood. In this paper, statistical analysis of turbulent vortices was performed using a novel vortex tracking algorithm. The vortices were identified using the normalized Q-criterion with extended volumes calculated using the Biot Savart law in order to capture most of the coherent structure related to each vortex. This new and fast algorithm makes it possible to estimate the volume of all resolved vortices. Turbulence was modeled using large-eddy simulation with the dynamic Smagorinsky-Lilly subgrid scale model for different Reynolds numbers. Number density of turbulent vortices were quantified and compared with different models. It is concluded that the calculated number densities for vortices in the inertial subrange and also for the larger scales are in very good agreement with the models proposed by Batchelor and Martinez-Bazan. Moreover, the associated enstrophy within the same size of coherent structures is quantified and its distribution is compared to models for distribution of turbulent kinetic energy. The associated enstrophy within the same size of coherent structures has a wide distribution that is normal distributed in the logarithmic scale.

DROP

FLUID PARTICLES

Biot-Savart law

FLOW

Turbulence

LES

IDENTIFICATION

SIMULATION

Enstrophy

Vortex properties

DISPERSIONS

Vortex identification algorithm

MODELS

BUBBLE BREAKUP

VORTEX

Författare

Farideh Ghasempour

Chalmers, Kemi- och bioteknik, Kemisk reaktionsteknik

Ronnie Andersson

Chalmers, Kemi- och bioteknik, Kemisk apparatteknik

Chalmers, Kemi- och bioteknik, Kemisk reaktionsteknik

Bengt Andersson

Chalmers, Kemi- och bioteknik, Kemisk reaktionsteknik

Applied Mathematical Modelling

0307-904X (ISSN)

Vol. 38 4226-4237

Ämneskategorier

Kemiteknik

DOI

10.1016/j.apm.2014.03.003