scholarly journals Computational Fluid Dynamics of Mixing Performance in Microchannel

2020 ◽  
Author(s):  
Siti Nor Azreen Ahmad Termizi ◽  
Syamsul Rizal Abd Shukor
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Mixing Performance

scholarly journals The Hydrodynamics and Mixing Performance in a Moving Baffle Oscillatory Baffled Reactor through Computational Fluid Dynamics (CFD)

Processes ◽  
2020 ◽  
Vol 8 (10) ◽  
pp. 1236
Author(s):  
Hamid Mortazavi ◽  
Leila Pakzad
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Dispersion Coefficient ◽  
Velocity Ratio ◽  
Axial Dispersion ◽  
Shear Strain Rate ◽  
Turbulent Length Scale ◽  
Mixing Performance ◽  
Axial Dispersion Coefficient ◽  
Computational Fluid Dynamics Cfd

Oscillatory baffled reactors (OBRs) have attracted much attention from researchers and industries alike due to their proven advantages in mixing, scale-up, and cost-effectiveness over conventional stirred tank reactors (STRs). This study quantitatively investigated how different mixing indices describe the mixing performance of a moving baffle OBR using computational fluid dynamics (CFD). In addition, the hydrodynamic behavior of the reactor was studied, considering parameters such as the Q-criterion, shear strain rate, and velocity vector. A modification of the Q-criterion showed advantages over the original Q-criterion in determination of the vortices’ locations. The dynamic mesh tool was utilized to simulate the moving baffles through ANSYS/Fluent. The mixing indices studied were the velocity ratio, turbulent length scale, turbulent time scale, mixing time, and axial dispersion coefficient. We found that the oscillation amplitude had the most significant impact on these indices. In contrast, the oscillatory Reynolds number did not necessarily describe the mixing intensity of a system. Of the tested indices, the axial dispersion coefficient showed advantages over the other indices for quantifying the mixing performance of a moving baffle OBR.

scholarly journals Numerical Investigation on Multiphase Flows in Various Configurations of Microchannels Using Computational Fluid Dynamics

2019 ◽  
Vol 17 (1) ◽  
pp. 82
Author(s):  
Mohd Fadhil Majnis ◽  
Mohamad Rawad Jalwan
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Fluid Flows ◽  
Chaotic Advection ◽  
Computational Domain ◽  
Mixing Performance ◽  
Vof Model ◽  
Computational Fluid Dynamics Cfd ◽  
Miscible Liquids ◽  
Grid Independence

A two-dimensional domain of multiphase flow analyses in this study using the Volume of Fluid (VOF) model was carried out in order to simulate and predict the fluid flows and mixing performance of two miscible liquids in various microchannel configurations. The various microchannels configurations were designed accordingly and the simulation was carried out based on the justified conditions, assumptions and considerations by using the commercial computational fluid dynamics (CFD) software, FLUENT. The grid type and size of the computational domain were verified in terms of stability by performing the grid independence analysis. The result showed that static mixing would be possible to achieve in various configurations of microchannels, however, the simulation results predicted that it appeared to be more efficient in complex and retrofitted microchannels. It showed the potential to promote and enhance chaotic advection, compositions distribution, and diffusivity as compared to basic microchannels that are mostly dependent only on the injection focus. Furthermore, the Reynolds number appeared to be a significant factor to enhance the mixing performance in microchannel beside the configurations.

scholarly journals Mixing Performance of Counter-Axial Flow Impeller using Computational Fluid Dynamics

2018 ◽  
Vol 8 (02) ◽  
Author(s):  
Ian Torotwa ◽  
Changying Ji
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Axial Flow ◽  
Turbulence Models ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Ansys Fluent ◽  
Rushton Turbine ◽  
Mixing Performance ◽  
Computational Fluid Dynamics Cfd

In this study, turbulent flow fields in a baffled vessel stirred by counter-axial flow impeller have been investigated in comparison to the Rushton turbine. The resultant turbulence was numerically predicted using computational fluid dynamics (CFD). Turbulence models were developed in ANSYS Fluent 18.1 solver using the Navier-Stokes equation with the standard k-ε turbulence model. The Multiple Reference Frame (MRF) approach was used to simulate the impeller action in the vertical and horizontal planes of the stirred fluid volume. Velocity profiles generated from the simulations were used to predict and compare the performance of the two designs. To validate the CFD model, the simulation results were compared with experimental results from existing work and a satisfactory agreement was established. It was concluded that the counter-axial flow impeller could provide better turbulence characteristics that would improve the quality of mixing systems.

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