Energy and water vapor transport across a simplified cloud-clear air interface

32nd UIT (Italian Union of Thermo–fluid-dynamics) Heat Transfer Conference

物理学;力学

Gallana, L.^1 ; Di Savino, S.^1 ; De Santi, F.^1 ; Iovieno, M.^1 ; Tordella, D.^1

Dipartimento di Ingegneria Meccanica e Aerospaziale, Politecnico di Torino, Corso Duca degli Abruzzi 24, Torino

10129, Italy^1

关键词: Boussinesq model;    Interfacial region;    Planetary boundary layers;    Temporal evolution;    Turbulent regions;    Vapor concentrations;    Velocity fluctuations;    Water vapor transport;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/547/1/012042/pdf
DOI  :  10.1088/1742-6596/547/1/012042

学科分类：力学，机械学

来源: IOP

【 摘 要 】

We consider a simplified physics of the could interface where condensation, evaporation and radiation are neglected and momentum, thermal energy and water vapor transport is represented in terms of the Boussinesq model coupled to a passive scalar transport equation for the vapor. The interface is modeled as a layer separating two isotropic turbulent regions with different kinetic energy and vapor concentration. In particular, we focus on the small scale part of the inertial range of the atmospheric boundary layer as well as on the dissipative range of scales which are important to the micro-physics of warm clouds. We have numerically investigated stably stratified interfaces by locally perturbing at an initial instant the standard temperature lapse rate at the cloud interface and then observing the temporal evolution of the system. When the buoyancy term becomes of the same order of the inertial one, we observe a spatial redistribution of the kinetic energy which produce a concomitant pit of kinetic energy within the mixing layer. In this situation, the mixing layer contains two interfacial regions with opposite kinetic energy gradient, which in turn produces two intermittent sublayers in the velocity fluctuations field. This changes the structure of the field with respect to the corresponding non-stratified shearless mixing: the communication between the two turbulent region is weak, and the growth of the mixing layer stops. These results are discussed with respect to Large Eddy Simulations data for the Planetary Boundary Layers.