Evaporation into Couette Flow
Abstract
The equation governing the evaporation from a microliter droplet of a chemical warfare agent into Couette flow is derived using an integral method. It is assumed that the evaporation from a small drop is controlled by the linear velocity distribution in the near wall region of a laminar or turbulent atmospheric boundary layer. The result is presented in terms of nondimensional parameters: Sherwood (Sh) number as a function of Reynolds (Re) number to the 2/3 power, and Schmidt (Sc) number to the 1/3 power with a 0.852 constant of proportionality. These results are confirmed using a Crank-Nicolson implicit solution of the diffusion equation. In addition to agreement between the integral and numerical results for the diffusion rate, good agreement is also obtained in the computed concentration distributions with the profiles assumed in the integral analysis. Evaporation rate predictions are compared to evaporation rate measurements of HD droplets on a glass surface obtained in the U.S. Army Edgewood Chemical Biological Center 5-cm wind tunnels. The average slope of the Sh number data versus the Re number Sc number parameter is 0.98, which exceeds the theoretical results by 13%, but the prediction falls within two standard deviations of + or -17%.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 2008
- Accession Number
- ADA477975
Entities
People
- James E. Danberg
Organizations
- Leidos