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Multidimensional turbulence spectra - Statistical analysis of turbulent vortices

Farideh Ghasempour (Institutionen för kemi- och bioteknik, Kemisk reaktionsteknik) ; Ronnie Andersson (Institutionen för kemi- och bioteknik, Kemisk reaktionsteknik ; Institutionen för kemi- och bioteknik, Kemisk apparatteknik) ; Bengt Andersson (Institutionen för kemi- och bioteknik, Kemisk reaktionsteknik)
Applied Mathematical Modelling (0307-904X). Vol. 38 (2014), 17-18, p. 4226-4237.
[Artikel, refereegranskad vetenskaplig]

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.

Nyckelord: Turbulence, Vortex identification algorithm, Vortex properties, Enstrophy, Biot-Savart law, LES, FLUID PARTICLES, BUBBLE BREAKUP, FLOW, DISPERSIONS, MODELS, IDENTIFICATION, SIMULATION, VORTEX, DROP



Denna post skapades 2014-10-22. Senast ändrad 2016-07-13.
CPL Pubid: 204693

 

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Institutioner (Chalmers)

Institutionen för kemi- och bioteknik, Kemisk reaktionsteknik (2005-2014)
Institutionen för kemi- och bioteknik, Kemisk apparatteknik (2005-2014)

Ämnesområden

Kemiteknik

Chalmers infrastruktur

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Structures, Properties and Dynamics of Turbulent Vortices