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Title: Investigation of Turbulent Entrainment-Mixing Processes With a New Particle-Resolved Direct Numerical Simulation Model

Abstract

Here, a new particle-resolved three dimensional direct numerical simulation (DNS) model is developed that combines Lagrangian droplet tracking with the Eulerian field representation of turbulence near the Kolmogorov microscale. Six numerical experiments are performed to investigate the processes of entrainment of clear air and subsequent mixing with cloudy air and their interactions with cloud microphysics. The experiments are designed to represent different combinations of three configurations of initial cloudy area and two turbulence modes (decaying and forced turbulence). Five existing measures of microphysical homogeneous mixing degree are examined, modified, and compared in terms of their ability as a unifying measure to represent the effect of various entrainment-mixing mechanisms on cloud microphysics. Also examined and compared are the conventional Damköhler number and transition scale number as a dynamical measure of different mixing mechanisms. Relationships between the various microphysical measures and dynamical measures are investigated in search for a unified parameterization of entrainment-mixing processes. The results show that even with the same cloud water fraction, the thermodynamic and microphysical properties are different, especially for the decaying cases. Further analysis confirms that despite the detailed differences in cloud properties among the six simulation scenarios, the variety of turbulent entrainment-mixing mechanisms can be reasonablymore » represented with power-law relationships between the microphysical homogeneous mixing degrees and the dynamical measures.« less

Authors:
 [1]; ORCiD logo [2];  [1]; ORCiD logo [3]
  1. Stony Brook Univ., NY (United States). Dept. of Applied Mathematics and Statistics
  2. Stony Brook Univ., NY (United States). Dept. of Applied Mathematics and Statistics; Brookhaven National Lab. (BNL), Upton, NY (United States)
  3. Nanjing Univ. of Technology (China). State Key Lab. for Aerosol-Cloud-Precipitation of China Meteorological Administration
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23); USDOE Office of Science (SC), Advanced Scientific Computing Research (ASCR) (SC-21); US Army Research Office (ARO); National Natural Science Foundation of China (NNSFC)
OSTI Identifier:
1424986
Report Number(s):
BNL-203223-2018-JAAM
Journal ID: ISSN 2169-897X
Grant/Contract Number:  
SC0012704; W911NF-15-1-0403; 91537108; BK20160041
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Geophysical Research: Atmospheres
Additional Journal Information:
Journal Volume: 123; Journal Issue: 4; Journal ID: ISSN 2169-897X
Publisher:
American Geophysical Union
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES

Citation Formats

Gao, Zheng, Liu, Yangang, Li, Xiaolin, and Lu, Chunsong. Investigation of Turbulent Entrainment-Mixing Processes With a New Particle-Resolved Direct Numerical Simulation Model. United States: N. p., 2018. Web. doi:10.1002/2017JD027507.
Gao, Zheng, Liu, Yangang, Li, Xiaolin, & Lu, Chunsong. Investigation of Turbulent Entrainment-Mixing Processes With a New Particle-Resolved Direct Numerical Simulation Model. United States. doi:10.1002/2017JD027507.
Gao, Zheng, Liu, Yangang, Li, Xiaolin, and Lu, Chunsong. Mon . "Investigation of Turbulent Entrainment-Mixing Processes With a New Particle-Resolved Direct Numerical Simulation Model". United States. doi:10.1002/2017JD027507.
@article{osti_1424986,
title = {Investigation of Turbulent Entrainment-Mixing Processes With a New Particle-Resolved Direct Numerical Simulation Model},
author = {Gao, Zheng and Liu, Yangang and Li, Xiaolin and Lu, Chunsong},
abstractNote = {Here, a new particle-resolved three dimensional direct numerical simulation (DNS) model is developed that combines Lagrangian droplet tracking with the Eulerian field representation of turbulence near the Kolmogorov microscale. Six numerical experiments are performed to investigate the processes of entrainment of clear air and subsequent mixing with cloudy air and their interactions with cloud microphysics. The experiments are designed to represent different combinations of three configurations of initial cloudy area and two turbulence modes (decaying and forced turbulence). Five existing measures of microphysical homogeneous mixing degree are examined, modified, and compared in terms of their ability as a unifying measure to represent the effect of various entrainment-mixing mechanisms on cloud microphysics. Also examined and compared are the conventional Damköhler number and transition scale number as a dynamical measure of different mixing mechanisms. Relationships between the various microphysical measures and dynamical measures are investigated in search for a unified parameterization of entrainment-mixing processes. The results show that even with the same cloud water fraction, the thermodynamic and microphysical properties are different, especially for the decaying cases. Further analysis confirms that despite the detailed differences in cloud properties among the six simulation scenarios, the variety of turbulent entrainment-mixing mechanisms can be reasonably represented with power-law relationships between the microphysical homogeneous mixing degrees and the dynamical measures.},
doi = {10.1002/2017JD027507},
journal = {Journal of Geophysical Research: Atmospheres},
number = 4,
volume = 123,
place = {United States},
year = {Mon Feb 19 00:00:00 EST 2018},
month = {Mon Feb 19 00:00:00 EST 2018}
}

Journal Article:
Free Publicly Available Full Text
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