Turbulent and reactive flows

We deal with turbulence modeling and simulation of turbulent flows. Recent research activities include:

rmsu_re180_dns_filt

RMS of longitudinal velocity

Development of anisotropic models for Large Eddy Simulation

The subgrid stress tensor is supposed to have a tensorial relation with the strain rate tensor. In the figure the r.m.s. (root mean square) values of longitudinal velocity component for a plane channel flow at Reτ=180 are plotted and compared to an isotropic model, to Direct Numerical Simulations and to experimental data.

Turbulent convection between two infinite parallel planes

We employ a dynamic Large Eddy Simulation model for turbulent convection at Rayleigh number 109. In the figure the isosurfaces of temperature showing the most intense upwelling thermal convection plumes are plotted.

 

Upwelling thermal plumes in turbulent convection

Upwelling thermal plumes in turbulent convection

Ice formation (gray) in turbulent convection downwelling plumes (light blue)

Ice formation (gray) in turbulent convection downwelling plumes (light blue)

Ice formation in supercooled free surface of oceans

The fluid is in turbulent convective regime. We use Boussinesq approximation for the water-ice mixture and we employ a dynamic LES model. In the figures: in light blue are plotted the downwelling cold thermal plumes, in gray the ice formation regions. Top figure: fast formation regime: ice is contained inside most intense downwelling plume. Bottom figure: slow formation regime: ice is present in wide areas.

LES of the flow around two in-tandem plates

The flow around two in-tandem plates normal to the free-stream velocity at Re=8000 has been simulated with LES. The obtained vorticity field (upper figure) is compared with experiments (lower figure).
In the movie for the Pressure,  counter rotating vortices and three-dimensional structures with fluid ejection in vertical direction are observed [G. Gibertini et al., Flow Around Two In-Tandem Flat Plates: Measurements and Computations Comparison. 5th International Conference on Vortex Flows and Vortex Models (ICVFM2010)]

 

vort_Bdc12_vort_19-B

Hybrid RANS/LES model

The periodic hill flow represents a classic test case for hybrid RANS/LES methods. The figure shows a longitudinal velocity visualization and  refers to a simulation performed with  the hybrid RANS-reconstructed method presented in [A.Abbà et al., “A DG Implementation of a Novel Hybrid RANS/LES Technique With RANS Reconstruction”,  http://arxiv.org/abs/1411.4882]. In particular, in these simulations a constant RANS/LES blending factor equal to 0.5 has been considered. The numerical results show a good qualitative behaviour, with a separated flow after the first hill.

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View a list of publications related to turbulence modeling and turbulent flows