Round turbulent thermals, puffs, starting plumes and starting jets in uniform crossflow

F. J. Diez, L. P. Bernal, G. M. Faeth

Research output: Contribution to journalArticlepeer-review

21 Scopus citations

Abstract

The self-preserving properties of round turbulent thermals, puffs, starting plumes and starting jets, in unstratified and uniform crossflow, were investigated experimentally. The experiments involved dye-containing fresh water (for nonbuoyant flows) and salt water (for buoyant flows) sources injected vertically downward into crossflowing fresh water within a water channel. Time-resolved video images of the flows were obtained using CCD cameras. Experimental conditions were as follows: source exit diameters of 3.2 and 6.4 mm, source Reynolds numbers of 2,500-16,000, source/ambient velocity ratios of 4-35, source/ambient density ratios (for buoyant flows) of 1.073 and 1.150, volumes of injected source fluid (for thermals and puffs) comprising 16-318 source diameters, streamwise (vertical) penetration distances of 0-200 source diameters and 0-13 Morton length scales (for buoyant flows) and crosstream (horizontal) penetration distances of 0-620 source diameters. Near-source behavior varied significantly with source properties and distance from the source but the flows generally became turbulent for streamwise distances within 5 source diameters from the source and became self-preserving for streamwise distances from the source greater than 40-50 source diameters. Crosstream motion satisfied the no-slip convection approximation. Streamwise motion for self-preserving conditions satisfied the behavior of corresponding self-preserving flows in still fluids: round thermals and puffs in still fluids for round thermals and puffs in crossflow and two-dimensional line thermals and puffs in still fluids for round starting plumes and jets in crossflow. The no-slip convection approximation for crossflow motion combined with self-preserving approximations for streamwise motion were also effective for predicting flow trajectories at self-preserving conditions for steady round turbulent plumes and jets in crossflow.

Original languageEnglish (US)
Pages (from-to)1046-1057
Number of pages12
JournalJournal of Heat Transfer
Volume125
Issue number6
DOIs
StatePublished - Dec 2003
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

Keywords

  • Heat transfer
  • Jets
  • Plumes
  • Scaling
  • Thermal
  • Turbulence

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