Mixing dynamics in an uncovered unbaffled stirred tank using Large-Eddy Simulations and a passive scalar transport equation

2020 ◽  
Vol 222 ◽  
pp. 115658
Author(s):  
J. Ramírez-Cruz ◽  
M. Salinas-Vázquez ◽  
G. Ascanio ◽  
W. Vicente-Rodríguez ◽  
C. Lagarza-Córtes
Keyword(s):  
Transport Equation ◽  
Passive Scalar ◽  
Large Eddy Simulations ◽  
Scalar Transport ◽  
Stirred Tank ◽  
Passive Scalar Transport ◽  
Large Eddy ◽  
Mixing Dynamics

Numerical Investigations of Passive Scalar Transport in Turbulent Taylor-Couette Flows: Large Eddy Simulation Versus Direct Numerical Simulations

2012 ◽  
Vol 134 (4) ◽  
Author(s):  
Yacine Salhi ◽  
El-Khider Si-Ahmed ◽  
Gérard Degrez ◽  
Jack Legrand
Keyword(s):  
Finite Element ◽  
Large Eddy Simulation ◽  
Numerical Simulations ◽  
Passive Scalar ◽  
Direct Numerical Simulations ◽  
Scalar Transport ◽  
Eddy Simulation ◽  
Passive Scalar Transport ◽  
Large Eddy ◽  
Spectral Finite Element

The highly turbulent flow occurring inside (electro)chemical reactors requires accurate simulation of scalar mixing if computational fluid dynamics (CFD) methods are to be used with confidence in design. This has motivated the present paper, which describes the implementation of a passive scalar transport equation into a hybrid spectral/finite-element code. Direct numerical simulations (DNS) and large eddy simulation (LES) were performed to study the effects of gravitational and centrifugal potentials on the stability of incom-pressible Taylor-Couette flow. The flow is confined between two concentric cylinders with an inner rotating cylinder while the outer one is at rest. The Navier-Stokes equations with the uncoupled convection–diffusion–reaction (CDR) equation are solved using a code named spectral/finite element large eddy simulations (SFELES) which is based on spectral development in one direction combined with a finite element discretization in the remaining directions. The performance of the LES code is validated with published DNS data for channel flow. Velocity and scalar statistics showed good agreement between the current LES predictions and DNS data. Special attention was given to the flow field, in the vicinity of Reynolds number of 68.2 with radii ratio of 0.5. The effect of Sc on the concentration peak is pointed out while the magnitude of heat transfer shows a dependence of the Prandtl number with an exponent of 0.375.

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