Zur Kurzanzeige

Continuously driven phase separation: size distributions and time scales in droplet growth

dc.contributor.advisorJürgen, Vollmer Prof. Dr.
dc.contributor.authorRohloff, Martin
dc.date.accessioned2015-09-09T09:03:57Z
dc.date.available2015-09-09T09:03:57Z
dc.date.issued2015-09-09
dc.identifier.urihttp://hdl.handle.net/11858/00-1735-0000-0023-9610-E
dc.identifier.urihttp://dx.doi.org/10.53846/goediss-5247
dc.identifier.urihttp://dx.doi.org/10.53846/goediss-5247
dc.language.isoengde
dc.rights.urihttp://creativecommons.org/licenses/by-nc-nd/4.0/
dc.subject.ddc530de
dc.titleContinuously driven phase separation: size distributions and time scales in droplet growthde
dc.typedoctoralThesisde
dc.contributor.refereeMüller, Marcus Prof. Dr.
dc.date.examination2015-07-16
dc.subject.gokPhysik (PPN621336750)de
dc.description.abstractengPhase separation arises in mixtures when temperature, pressure or concentrations of the mixture is changed such that a new macroscopic phase emerges. Typically the domains of the new phase take the form of droplets, bubbles or solid particles. Many phenomena such as the synthesis of monodisperse colloidal particles, rain formation or geysers are caused by continuously driven phase separation where a sustained change of temperature, pressure or concentrations induces a continuous increase of the volume occupied by the domains. I use here (i) laboratory experiments on phase separation of liquid binary mixtures, (ii) numerical investigation of droplet assemblies evolving with overall volume growth, and (iii) theoretical modelling to study the evolution of the domain size distributions and the emerging time scales in the domain growth. Depending on the driving strength I identify a crossover from coarsening dynamics (Ostwald ripening) to size focussing in the domain size distributions. I give analytic expressions for the evolution of the size distribution in the size focussing regime that arises for sufficiently strong driving and I show that the size distribution can be rescaled for all times onto the initial distribution. These findings have immediate consequences for size distributions in nano-particle synthesis. When the droplets have grown to sizes where their motion is affected by buoyancy, sedimentation and collisions cause a runaway growth. The runaway leads to precipitation of the droplet volume out of the fluid and resets the system. For a sustained driving new droplets start to grow and eventually they will be removed by another wave of precipitation. We denote this oscillatory response to a continuous thermodynamic driving as episodic precipitation. The time scale of precipitation is set by the crossover from diffusive to collisional growth. The measured time scales collapse on a master curve predicted by an analytic model that is also developed in the thesis. Applying the model to the formation of warm rain gives reasonable values for the rain initiation time. The application of concepts developed in the present thesis to describe continuously driven phase separation thus provides valuable new insights for a wealth of different phenomena.de
dc.contributor.coRefereeJürgen, Vollmer Prof. Dr.
dc.subject.engphase separationde
dc.subject.engbinary fluidsde
dc.subject.engripeningde
dc.subject.engcloud physicsde
dc.subject.engprecipitationde
dc.subject.engmonodisperse colloidsde
dc.subject.engsize focussingde
dc.subject.engsynchronisationde
dc.identifier.urnurn:nbn:de:gbv:7-11858/00-1735-0000-0023-9610-E-4
dc.affiliation.instituteFakultät für Physikde
dc.identifier.ppn834791226


Dateien

Thumbnail

Das Dokument erscheint in:

Zur Kurzanzeige