气候变化领域集成服务门户(CCPortal): Intricate relations among particle collision, relative motion and clustering in turbulent clouds: computational observation and theory

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DOI	10.5194/acp-22-3779-2022
	Intricate relations among particle collision, relative motion and clustering in turbulent clouds: computational observation and theory
	Saw, Ewe-Wei; Meng, Xiaohui
发表日期	2022
ISSN	1680-7316
EISSN	1680-7324
起始页码	3779
结束页码	3788
卷号	22 期号:6 页码:10
英文摘要	Considering turbulent clouds containing small inertial particles, we investigate the effect of particle collision, in particular collision-coagulation, on particle clustering and particle relative motion. We perform direct numerical simulation (DNS) of coagulating particles in isotropic turbulent flow in the regime of small Stokes number (St = 0.001-0.54) and find that, due to collision-coagulation, the radial distribution functions (RDFs) fall off dramatically at scales r similar to d (where d is the particle diameter) to small but finite values, while the mean radial component of the particle relative velocity (MRV) increases sharply in magnitude. Based on a previously proposed Fokker-Planck (drift-diffusion) framework, we derive a theoretical account of the relationship among particle collision-coagulation rate, RDF and MRV. The theory includes contributions from turbulent fluctuations absent in earlier mean-field theories. We show numerically that the theory accurately accounts for the DNS results (i.e., given an accurate RDF, the theory could produce an accurate MRV). Separately, we also propose a phenomenological model that could directly predict MRV and find that it is accurate when calibrated using fourth moments of the fluid velocities. We use the model to derive a general solution of RDF. We uncover a paradox: the past empirical success of the differential version of the theory is theoretically unjustified. We see a further shape-preserving reduction of the RDF (and MRV) when the gravitational settling parameter (S-g) is of order O(1). Our results demonstrate strong coupling between RDF and MRV and imply that earlier isolated studies on either RDF or MRV have limited relevance for predicting particle collision rate.
学科领域	Environmental Sciences; Meteorology & Atmospheric Sciences
语种	英语
WOS研究方向	Environmental Sciences & Ecology ; Meteorology & Atmospheric Sciences
WOS记录号	WOS:000773398300001
来源期刊	ATMOSPHERIC CHEMISTRY AND PHYSICS
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/273932
作者单位	Sun Yat Sen University; Sun Yat Sen University
推荐引用方式 GB/T 7714	Saw, Ewe-Wei,Meng, Xiaohui. Intricate relations among particle collision, relative motion and clustering in turbulent clouds: computational observation and theory[J],2022,22(6):10.
APA	Saw, Ewe-Wei,&Meng, Xiaohui.(2022).Intricate relations among particle collision, relative motion and clustering in turbulent clouds: computational observation and theory.ATMOSPHERIC CHEMISTRY AND PHYSICS,22(6),10.
MLA	Saw, Ewe-Wei,et al."Intricate relations among particle collision, relative motion and clustering in turbulent clouds: computational observation and theory".ATMOSPHERIC CHEMISTRY AND PHYSICS 22.6(2022):10.