Kinematic and dynamic collision statistics of cloud droplets from high-resolution simulations

Video in TIB AV-Portal: Kinematic and dynamic collision statistics of cloud droplets from high-resolution simulations

Formal Metadata

Kinematic and dynamic collision statistics of cloud droplets from high-resolution simulations
Title of Series
CC Attribution 3.0 Unported:
You are free to use, adapt and copy, distribute and transmit the work or content in adapted or unchanged form for any legal purpose as long as the work is attributed to the author in the manner specified by the author or licensor.
Release Date

Content Metadata

Subject Area
We study the dynamic and kinematic collision statistics of cloud droplets for a range of flow Taylor microscale Reynolds numbers (up to 500), using a highly scalable hybrid direct numerical simulation approach. Accurate results of radial relative velocity (RRV) and radial distribution function (RDF) at contact have been obtained by taking advantage of their power-law scaling at short separation distances. Three specific but inter-related questions have been addressed in a systematic manner for geometric collisions of same-size droplets (of radius from 10 to 60 μm) in a typical cloud turbulence (dissipation rate at 400 cm2 s−3). Firstly, both deterministic and stochastic forcing schemes were employed to test the sensitivity of the simulation results on the large-scale driving mechanism. We found that, in general, the results are quantitatively similar, with the deterministic forcing giving a slightly larger RDF and collision kernel. This difference, however, is negligible for droplets of radius less than 30 μm. Secondly, we have shown that the dependence of pair statistics on the flow Reynolds number Rλ or larger scale fluid motion is of secondary importance, with a tendency for this effect to saturate at high enough Rλ leading to Rλ-independent results. Both DNS results and theoretical arguments show that the saturation happens at a smaller Rλ for smaller droplets. Finally, since most previous studies of turbulent collision of inertial particles concerned non-sedimenting particles, we have specifically addressed the role of gravity on collision statistics, by simultaneously simulating collision statistics with and without gravity. It is shown that the collision statistics is not affected by gravity when a < ac, where the critical droplet radius ac is found to be around 30 μm for the RRV, and around 20 μm for the RDF. For larger droplets, gravity alters the particle–eddy interaction time and significantly reduces the RRV. The effect of gravity on the RDF is rather complex: gravity reduces the RDF for intermediate-sized droplets but enhances the RDF for larger droplets. In addition, we have studied the scaling exponents of both RDF and RRV, and found that gravity modifies the RDF scaling exponents for both intermediate and large particles, in a manner very similar to the effect of gravity on the RDF at contact. Gravity is shown to cause the scaling exponents for RDF and RRV to level off for large droplets, in contrast to diminishing exponents for non-sedimenting particles.

Related Material

Prozessleittechnik Tongue and groove Paper Collision Clock Effects unit Electric power distribution Visible spectrum Wolkengattung Netztransformator Year Order and disorder (physics) Plain bearing Particle physics Negativer Widerstand Cogeneration Particle Separation process Hybrid rocket Video Cartridge (firearms) Fahrgeschwindigkeit Angeregter Zustand
Typesetting Collision Effects unit Electric power distribution Fahrgeschwindigkeit Sensor Ballpoint pen Cartridge (firearms) Mechanismus <Maschinendynamik> Star formation Scale (map)
Display device Green politics Composite material Domäne <Kristallographie> Vertical integration Particle Direct current Volumetric flow rate Vortex Video Book design Cylinder block Angeregter Zustand
Fahrgeschwindigkeit Musical ensemble Digital electronics Stock (firearms) Particle
Collision Electric power distribution Electric power distribution Optischer Halbleiterverstärker Measurement Radial engine Clothing sizes Chandrasekhar limit Particle Measurement Becherwerk Bill of materials Sizing Contactor McDonnell F-101 Voodoo Gabelstapler Noise figure Crystal twinning Model building Elektrische Isolierung Handgun
commissioner crisis of the behalf the that's a necessary step for what information this process is basically transformational small clock droplets handy growing lots and rehearsals of their eyes face research conducted in recent years because most straight but small state of motion can enhance the collagen right at the top a lot less in several different ways for example by arranging that idea of the velocity of the tongue jobless all right don't that just to at once that the description of the effect of the that once we may change these you to experiment and he put this in something studies of the jobless case and computational difficulties in law and order once case of that agreement floor you said yes then it might account simulation of multiphase flow can imagine us very important for momentum college colicins of the actual particles you know paper he started to pneumatic and dynamical issues that the states of the cloud droplets for this purpose we use high is called hybrid they might oscillation approach spectrum of a statement of simulation provides running intensive and accurate description of such clout processes
nursery object is hot and the 1st that's the way that the simulation results such as the distribution function what I have a lot of velocity the battle lasted forcing bad times we employ to leave enforcing schemes the deterministic this sparsity and we found 1 study any differences in the colleges that distance the 2nd problem concerns the effect of the floor in those numbers would be voluntary deferential the floors case that it isn't it and that the medical simulation the set objective is related to the than the seems most video studies on the global ecology were done for most certain as Iistening regime has been performed ball with ease and resolve gravity this
animation shows that kind of emotional the vorticity defeated the flows follows by this focused steam and there scene because actors represent basis of of the book The seeking money to the block greens and vertical lines show crowded Palen mention domain the compositions are ranch computational really knows in each subdomain that sign the individual processes the back from the simulation we use UCC fault processes along with more than a
global and flow we got a large number of particles computational domain is decomposed along the direction perpendicular to guarantee this allows to minimize the number of jobless crossing that subdomain boundaries the visualization displays the motion of particles in the Sox numbers your point 25 this state
of the motion of particles with 2 different stocks numbers but of the discussed ensemble does your point 25 the particles from a structure on around 1 in our told visible differences fast the particles clustered in different regions 2nd settling velocity
credit particles is visible logic
quantitative measure of droplet clustering he's of the distribution function the figures preserves the distribution function of nearly touching particles the results have been computed insulation to different forcing models for different sizes of particles and the veritable internal slumberous we found that there is as the present that I must understand that gene and the follows on that these are servers enough of them to the fence forcing schemes


  335 ms - page object


AV-Portal 3.20.2 (36f6df173ce4850b467c9cb7af359cf1cdaed247)