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NUMERICAL STUDY OF TURBULENT SUBMERGED BIFURCATED JETS IMPINGEMENT AND INTERACTIONS WITH A FREE SURFACE

Bernhard Righolt
Section of Transport Phenomena, Department of Chemical Engineering, Faculty of Applied Sciences Delft University of Technology and J. M. Burgerscentre for Fluid Dynamics Julianalaan, 2628 BL Delft

Sasa Kenjeres
Transport Phenomena Section, Department of Chemical Engineering, Faculty of Applied Sciences, Delft University of Technology and J.M. Burgerscentrum for Fluid Mechanics, Delft, The Netherlands

R. Kalter
Section of Transport Phenomena, Department of Chemical Engineering, Faculty of Applied Sciences Delft University of Technology and J. M. Burgerscentre for Fluid Dynamics Julianalaan, 2628 BL Delft

Mark J. Tummers
Section of Transport Phenomena, Department of Chemical Engineering, Faculty of Applied Sciences Delft University of Technology and J. M. Burgerscentre for Fluid Dynamics Julianalaan, 2628 BL Delft

Chris R. Kleijn
Section of Transport Phenomena, Department of Chemical Engineering, Faculty of Applied Sciences Delft University of Technology and J. M. Burgerscentre for Fluid Dynamics Julianalaan, 2628 BL Delft

Résumé

This paper presents the results of the numerical simulation of turbulent submerged jets, issuing from a bifurcated nozzle into a thin cavity with a free surface. The jet Reynolds number is Rejet = 1.25 × 104. The jets impinge on solid walls, creating large recirculation zones, moving anti-symmetrically in the symmetric domain. The flow below the free surface causes a significant disturbance of the free surface by the turbulent jets. The free surface is modeled using the Volume of Fluid (VOF) approach, and the turbulence closure is obtained using the standard k − ε TRANS model as well as with the dynamic Smagorinsky LES model.
The numerical results were assessed with experimental results (Kalter et al., 2013). We have shown that the numerical models capture the physics correctly. The occurrence of a long term asymmetric oscillation is also found in the numerical model for an LES grid of sufficient resolution. However, the inability of the numerical model to predict the close approach of the top recirculation zone to the nozzle is the major source for the differences found between models and experiment. While the dominant oscillation frequency of the long term oscillation was found at approximately 0.09Hz in the experiment, the LES model predicts this frequency at 0.14Hz.