TURBULENT DIFFUSION BEHIND VEHICLES: EXPERIMENTALLY DETERMINED TURBULENCE MIXING PARAMETERS

The wake of a moving vehicle was simulated using a specially constructed wind tunnel with a moving floor. A "blocked-shaped" model vehicle was fixed in position over the test-section floor while the floor moved at the freestream air speed to produce a uniform, shear-free, approach flow. This simulates an automobile traveling along a straight highway under calm atmospheric conditions. Vertical and lateral profiles of tracer gas concentration were obtained in the wake. Profiles were taken at distances of 30, 45, and 60 model heights downwind. The equations describing the wake theory were solved numerically to determine the "best" turbulence scale lengths by using a wind tunnel taken at 30 model heights downwind as the inflow boundary condition and comparing the numerical computation made at 60 heights downwind to the wind tunnel data taken at this location. It was found that the "best" scale lengths were the vehicle width along and across the wake, and height above the surface in the vertical directions, respectively.

• Supplemental Notes:
  • Published in Atmospheric Environment, Volume 20, No. 5, 1986, pp 851-860.
• Corporate Authors:

  Environmental Protection Agency

  Atmospheric Sciences Research Laboratory
  Research Triangle P., NC  United States  27709
• Authors:
  • ESKRIDGE, R E
  • Rao, S T
• Publication Date: 1986

Media Info

• Pagination: 12 p.

Subject/Index Terms

• TRT Terms: Diffusion (Optics); Exhaust gases; Flow; Mixing; Motor vehicles; Parametric equations; Simulation; Turbulence; Wind tunnels
• Candidate Terms: Turbulent flow
• Subject Areas: Highways; Operations and Traffic Management; Planning and Forecasting; Vehicles and Equipment; I72: Traffic and Transport Planning;

Filing Info

• Accession Number: 00475038
• Record Type: Publication
• Source Agency: National Technical Information Service
• Report/Paper Numbers: EPA/600/J-86/385
• Files: TRIS
• Created Date: Oct 31 1987 12:00AM