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Direct numerical simulation of the turbulent flow in a baffled tank driven by a Rushton turbine
Author(s) -
Gillissen J. J. J.,
Van den Akker H. E. A.
Publication year - 2012
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.13762
Subject(s) - rushton turbine , turbulence , mechanics , hydraulic turbines , turbine , computer simulation , flow (mathematics) , draft tube , mechanical engineering , engineering , physics
We present a direct numerical simulation (DNS) of the turbulent flow in a baffled tank driven by by a Rushton turbine. The DNS is compared to a Large Eddy Simulation (LES), a Reynolds Averaged Navier‐Stokes (RANS) simulation, Laser Doppler Velocimetry data, and Particle Image Velocimetry data from the literature. By Reynolds averaging the DNS‐data, we validate the turbulent viscosity hypothesis by demonstrating strong alignment between the Reynolds stress and the mean strain rate. Although the turbulent viscosity ν T in the DNS is larger than in the RANS simulation, the turbulent viscosity parameter C μ = ν T ϵ/k 2 , is an order of magnitude smaller than the standard 0.09 value of the k‐ϵ model. By filtering the DNS‐data, we show that the Smagorinsky constant C S is uniformly distributed over the tank with C S ≈ 0.1. Consequently, the dynamic Smagorisnky model does not improve the accuracy of the LES. © 2012 American Institute of Chemical Engineers AIChE J, 2012