Measurement of negative thermophoretic force
The rarefied gas flow phenomenon of thermophoresis is studied experimentally on a macroscopic spherical particle with a diameter of 5.1 cm for pressures ranging from 0.01 to 10 Pa (Knudsen numbers $Kn$ from 10 to 0.01, respectively). Size scaling with matching Knudsen numbers makes the results appli...
Gespeichert in:
Veröffentlicht in: | Journal of fluid mechanics 2016-10, Vol.805, p.207-221 |
---|---|
Hauptverfasser: | , , , |
Format: | Artikel |
Sprache: | eng |
Schlagworte: | |
Online-Zugang: | Volltext |
Tags: |
Tag hinzufügen
Keine Tags, Fügen Sie den ersten Tag hinzu!
|
Zusammenfassung: | The rarefied gas flow phenomenon of thermophoresis is studied experimentally on a macroscopic spherical particle with a diameter of 5.1 cm for pressures ranging from 0.01 to 10 Pa (Knudsen numbers
$Kn$
from 10 to 0.01, respectively). Size scaling with matching Knudsen numbers makes the results applicable to microscale particles such as aerosol droplets at atmospheric pressure. Two sets of measurements are presented. The first set, complemented by numerical modelling based on the solution of the ellipsoidal statistical Bhatnagar–Gross–Krook kinetic equation, is focused on a spherical particle of high thermal conductivity in close proximity to a heated wall. The second set is conducted for the same particle placed in a linear thermal gradient established between two parallel walls. Results show the first reproducible measurements of negative thermophoretic force acting on a spherical particle in the direction from cold to hot, with values of the order of 5 % of the maximum hot to cold force production. |
---|---|
ISSN: | 0022-1120 1469-7645 |
DOI: | 10.1017/jfm.2016.464 |