CFD–DEM simulation of turbulence modulation in horizontal pneumatic conveying--颗粒学报PARTICUOLOGY

Ebrahimi, M., & Crapper, M. (2017). CFD–DEM simulation of turbulence modulation in horizontal pneumatic conveying. Particuology, 31, 15-24. https://doi.org/10.1016/j.partic.2016.05.012

CFD–DEM simulation of turbulence modulation in horizontal pneumatic conveying

Mohammadreza Ebrahimi ^a, Martin Crapper ^b *

a Institute for Infrastructure and Environment, School of Engineering, The University of Edinburgh, The King’s Buildings, Edinburgh EH9 3JL, UK
b Department of Mechanical and Construction Engineering, Northumbria University, Ellison Place, Newcastle-upon-Tyne, NE1 8ST, UK

10.1016/j.partic.2016.05.012

Volume 31, April 2017, Pages 15-24

Received 14 June 2015, Revised 4 May 2016, Accepted 18 May 2016, Available online 15 October 2016, Version of Record 9 March 2017.

E-mail: Martin.Crapper@Northumbria.ac.uk

Highlights

• The hybrid source terms were added to the standard k–ε turbulence model.

• Simulation results revealed that turbulence intensity depends on the values of constant C_ε3.

• The higher the C_ε3 constant, the lower the turbulence intensity predicted.

• The k–ε turbulence model is not well suited to modelling a particle–fluid system.

Abstract

A study is presented to evaluate the capabilities of the standard k–ε turbulence model and the k–ε turbulence model with added source terms in predicting the experimentally measured turbulence modulation due to the presence of particles in horizontal pneumatic conveying, in the context of a CFD–DEM Eulerian–Lagrangian simulation. Experiments were performed using a 6.5-m long, 0.075-m diameter horizontal pipe in conjunction with a laser Doppler anemometry (LDA) system. Spherical glass beads with two sizes, 1.5 and 2 mm, were used. Simulations were performed using the commercial discrete element method software EDEM, coupled with the computational fluid dynamics package FLUENT. Hybrid source terms were added to the conventional k–ε turbulence model to take into account the influence of the dispersed phase on the carrier phase turbulence intensity. The simulation results showed that the turbulence modulation depends strongly on the model parameter C_ε3. Both the standard k–ε turbulence model and the k–ε turbulence model with the hybrid source terms could predict the gas phase turbulence intensity trend only generally. A noticeable discrepancy in all cases between simulation and experimental results was observed, particularly for the regions close to the pipe wall. It was also observed that in some cases the addition of the source terms to the k–ε turbulence model did not improve the simulation results when compared with those of the standard k–ε turbulence model. Nonetheless, in the lower part of the pipe where particle loading was greater due to gravitational effects, the model with added source terms performed somewhat better.

Graphical abstract

Keywords

Turbulence modulation; Pneumatic conveying; Eulerian–Lagrangian approach; Laser Doppler anemometry

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