We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
Influence of Coherent Vortex Rolls on Particle Dynamics in Unstably Stratified Turbulent Channel Flows.
- Authors
Zaza, Domenico; Iovieno, Michele
- Abstract
This work investigates the dynamics of heavy particles dispersed in turbulent channel flows under unstable thermal stratification conditions using point-particle direct numerical simulations (PP-DNS), to quantify the influence of large-scale coherent vortex rolls, arising from the combined effects of shear and buoyancy, on the spatial distribution and preferential sampling behavior of inertial particles. We examined three particle Stokes numbers ( St + = 0.6 , 60 , 120 ) and two friction Richardson numbers, Ri τ = 0.272 and Ri τ = 27.2 , which exemplify the regimes below and above the critical condition for vortex roll formation, respectively. The results indicate that the flow reorganization into large-scale longitudinal vortices significantly alters the topological features of small scales in the near-wall region impinged by the thermal plumes, resulting in a prevalence of vorticity-dominated topologies. The interplay between this phenomenon and the tendency of particles to preferentially sample strain-dominated topologies leads to a distinctive asymmetric particle distribution in the near-wall planes. Inertial particles markedly accumulate in the strain-dominated regions where the coherent thermal plumes emerge from the walls, while avoiding the vorticity-dominated impingement zones. This peculiar particle response to the vortex rolls is most pronounced when the particle response time matches the characteristic timescale of the large-scale coherent motions in the cross-stream planes.
- Subjects
CHANNEL flow; TURBULENT flow; TURBULENCE; PARTICLE dynamics; RICHARDSON number; STRATIFIED flow; PLUMES (Fluid dynamics)
- Publication
Energies (19961073), 2024, Vol 17, Issue 11, p2725
- ISSN
1996-1073
- Publication type
Article
- DOI
10.3390/en17112725