Phase Relaxation Time in Open Chaotic Billiards

1998 ◽  
Vol 67 (9) ◽  
pp. 3003-3005 ◽  
Author(s):  
Yositake Takane
Keyword(s):  
Relaxation Time ◽  
Phase Relaxation ◽  
Chaotic Billiards ◽  
Phase Relaxation Time

scholarly journals Influence of Microphysical Variability on Stochastic Condensation in a Turbulent Laboratory Cloud

2018 ◽  
Vol 75 (1) ◽  
pp. 189-201 ◽  
Author(s):  
N. Desai ◽  
K. K. Chandrakar ◽  
K. Chang ◽  
W. Cantrell ◽  
R. A. Shaw
Keyword(s):  
Relaxation Time ◽  
Size Distribution ◽  
Droplet Size ◽  
Droplet Size Distribution ◽  
Number Concentration ◽  
Droplet Growth ◽  
Diffusional Growth ◽  
Phase Relaxation ◽  
Distribution Width ◽  
Phase Relaxation Time

Diffusional growth of droplets by stochastic condensation and a resulting broadening of the size distribution has been considered as a mechanism for bridging the cloud droplet growth gap between condensation and collision–coalescence. Recent studies have shown that supersaturation fluctuations can lead to a broadening of the droplet size distribution at the condensational stage of droplet growth. However, most studies using stochastic models assume the phase relaxation time of a cloud parcel to be constant. In this paper, two questions are asked: how variability in droplet number concentration and radius influence the phase relaxation time and what effect it has on the droplet size distributions. To answer these questions, steady-state cloud conditions are created in the laboratory and digital inline holography is used to directly observe the variations in local number concentration and droplet size distribution and, thereby, the integral radius. Stochastic equations are also extended to account for fluctuations in integral radius and obtain new terms that are compared with the laboratory observations. It is found that the variability in integral radius is primarily driven by variations in the droplet number concentration and not the droplet radius. This variability does not contribute significantly to the mean droplet growth rate but does contribute significantly to the rate of increase of the size distribution width.

scholarly journals Theoretical analysis of mixing in liquid clouds – Part 3: Inhomogeneous mixing

2016 ◽  
Vol 16 (14) ◽  
pp. 9273-9297 ◽  
Author(s):  
Mark Pinsky ◽  
Alexander Khain ◽  
Alexei Korolev
Keyword(s):  
Relaxation Time ◽  
Equilibrium State ◽  
Mixing Time ◽  
Total Duration ◽  
Droplet Size Distribution ◽  
Liquid Water Content ◽  
Phase Relaxation ◽  
Cloud Droplets ◽  
Wide Range ◽  
Phase Relaxation Time

Abstract. An idealized diffusion–evaporation model of time-dependent mixing between a cloud volume and a droplet-free volume is analyzed. The initial droplet size distribution (DSD) in the cloud volume is assumed to be monodisperse. It is shown that evolution of the microphysical variables and the final equilibrium state are unambiguously determined by two non-dimensional parameters. The first one is the potential evaporation parameter R, proportional to the ratio of the saturation deficit to the liquid water content in the cloud volume, that determines whether the equilibrium state is reached at 100 % relative humidity, or is characterized by a complete evaporation of cloud droplets. The second parameter Da is the Damkölher number equal to the ratio of the characteristic mixing time to the phase relaxation time. Parameters R and Da determine the type of mixing.The results are analyzed within a wide range of values of R and Da. It is shown that there is no pure homogeneous mixing, since the first mixing stage is always inhomogeneous. The mixing type can change during the mixing process. Any mixing type leads to formation of a tail of small droplets in DSD and, therefore, to DSD broadening that depends on Da. At large Da, the final DSD dispersion can be as large as 0.2. The total duration of mixing varies from several to 100 phase relaxation time periods, depending on R and Da.The definitions of homogeneous and inhomogeneous types of mixing are reconsidered and clarified, enabling a more precise delimitation between them. The paper also compares the results obtained with those based on the classic mixing concepts. >

Influence of Interfacial Exchange Interaction on the Two-Phase Relaxation Time of Superparamagnetic Nanoparticles

2014 ◽  
Vol 893 ◽  
pp. 153-157
Author(s):  
Leonid L. Afremov ◽  
Ilia G. Iliushin
Keyword(s):  
Relaxation Time ◽  
Magnetic Relaxation ◽  
Superparamagnetic Nanoparticles ◽  
Exchange Constant ◽  
Phase Relaxation ◽  
Two Phase ◽  
Interphase Interaction ◽  
Constant Magnitude ◽  
Magnetic States ◽  
Phase Relaxation Time

Within the frame of two-phase superparamagnetic nanoparticles the effect of magnetic and geometric properties of superparamagnetic nanoparicles on the time of their magnetic relaxation has been defined. With increasing of volume the time of relaxation grows rapidly. Metastability conditions of magnetic states have been developed. Growth of exchange constant magnitude of interphase interaction results in increasing of relaxation time regardless of exchange constant sign.

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