## Abstract

solid particles in a fully-developed pipe flow at Re_{τ} = 360 is studied using direct numerical simulations. The particle volume fractions are small enough that inter-particle collisions can be neglected. The continuous and the dispersed phases are treated using the Eulerian and the Lagrangian approaches respectively. A second-order accurate, finite-volume based, Adams-Bashforth fractional-step scheme is used to integrate the unsteady, three-dimensional Navier-Stokes equations. The particle equation of motion included only the drag force and is integrated using a fourth-order accurate Runge-Kutta method. The effects of particle response time on fluid turbulence, at fixed particle volume and mass fractions of 6.84 × 10^{-5} and 0.17 respectively, are investigated. Particles of three different diameters d^{+}_{P} = 0.432,0.648,0.864 (in wall units) are tracked. It is observed that two-way coupling reduces the preferential concentration of particles near the wall (i.e. turbophoresis). Also, the mean stream-wise velocities and the RMS velocities of the continuous phase remain practically unchanged due to two-way coupling. However, significant augmentation of turbulence, especially at the smaller dissipative scales, can be seen in the energy spectra at certain radial locations. It is seen from the longitudinal energy spectra that the greatest degree of turbulence augmentation occurs at radial locations close to the pipe center and the pipe wall. In the case of azimuthal spectra, turbulence augmentation is seen only at radial locations close to the pipe center. The three different particles have similar qualitative as well as quantitative effects on the energy spectra. It is observed qualitatively from the velocity vectors in a pipe cross-section that two-way coupling reduces the strength of the hairpin vortices. In addition, two-way coupling dissipates the streaky nature of near wall turbulence.

Original language | English (US) |
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State | Published - 2000 |

Event | 35th Intersociety Energy Conversion Engineering Conference and Exhibit 2000 - Las Vegas, NV, United States Duration: Jul 24 2000 → Jul 28 2000 |

### Other

Other | 35th Intersociety Energy Conversion Engineering Conference and Exhibit 2000 |
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Country/Territory | United States |

City | Las Vegas, NV |

Period | 7/24/00 → 7/28/00 |

## ASJC Scopus subject areas

- Energy Engineering and Power Technology
- Renewable Energy, Sustainability and the Environment