uwe thiele
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Main scientific interest

My present main interest is the interface-dominated dynamics of complex liquids and soft matter, i.e., the influence of capillarity, wettability and/or internal structural forces on dynamical processes like, dewetting, deposition, crystallisation, phase separation, etc.. This includes active (biologically inspired) media.

Examples are (driven) droplets on homogeneous and heterogeneous substrates; surface-active substances, e.g., in Langmuir-Blodgett transfer; (active) liquid crystals; colloidal (nano)particle suspensions and polymer solutions; self-propelled droplets; and multilayer fluid systems. Related side interests include epitaxial growth, crystallisation dynamics and gelation processes; the dynamics of phase transitions; ratchet-driven transport in nano- and micro-fluidic systems; dynamics of wetting transitions of binary and ternary systems;

An important objective is to understand the structure forming interaction of the various interdependent advective and diffusive transport processes, phase transitions and possibly chemical reactions. On this basis one may successfully control the pertinent experimental systems and technological applications from coating and printing processes to bottom-up nanostructuring and micro- (and nano-)fluidics.

The various systems are investigated employing and developing analytical and numerical tools of nonlinear science. To facilitate students to enter the field early on (even with their Bachelor theses) we are building up the Münsteranian Torturials - set of hands-on tutorials on nonlinear science (numerical path-following and time-stepping methods, analytical methods - slowly but continuously progressing)
see CeNoS website under "Lehre", then "M√ľnsteranian Torturials" (direct link)

Scientific disciplines and model types

Many of the individual systems are situated in the twilight zone between physics, biology, chemistry and the engineering sciences and are described with methods of Theoretical Physics, Chemical and Biological Physics, Applied Mathematics, including non-equilibrium and equilibrium thermodynamics and statistical physics, physico-chemical hydrodynamics, surface science and nonlinear science.

The aim to understand soft matter systems on mesoscopic scales is pursued through the application, further development and analysis of a variety of microscopic stochastic discrete and microscopic and mesoscopic deterministic continuum descriptions. Examples include kinetic Monte Carlo models, Molecular Dynamics approaches, phase field and phase field crystal models, Dynamical Density Functional Theory and mesoscopic hydrodynamic models.

Analytical and Computational Approach

As the investigated effects are rather complex and the models are nonlinear, the reach of analytical approaches is limited. Analytically, one may study the linear and marginal stability of trivial steady and stationary states and of selected non-trivial ones; asymptotic methods often allow to determine the solution structure far away from the interesting transitions; and bifurcation theory allows for studies very close to some of the transitions.

The analytical work is accompanied by large-scale computations performed on systems ranging from standard laptops, to graphic cards (CUDA framework), and High Performance Parallel Computing systems. Numerical algorithms we develop and employ include standard finite difference methods or exponential propagation methods for the time stepping of ODE and PDE; pseudo arclength path continuation methods to determine steady and stationary states, and time-periodic space-dependent states. We also work on micro-meso hybrid methods, e.g., by matching Molecular Dynamics / (D)DFT and mesoscopic hydrodynamics for nano-droplets on solid substrates.

Collaborations

There exist collaborations with a number of experimentally and theoretically working groups at Departments of Mathematics, Physics, Chemical and Mechanical Engineering of various institutions as, for example, at the University of California at Berkeley, Technische Universität Berlin, Université Libre de Bruxelles, Université Joseph Fourier Grenoble, Technion Haifa, Hong Kong University of Science and Technology, Loughborough University, University of Manchester, École Polytechnique Paris, Soochow University,

Particular Systems

Finally, I list some particular systems/effects I am interested in. The related studies can by found on the publication page under the numbers given at the end of the particular point. I distinguish emerging subjects where we are in the stage of literature study, preliminary calculations, or proposal writing; fully active subjects about which we published recently or plan to publish soon; and past subjects that we were very interested in in the past, but do at the moment (nearly) not work on actively.

Emerging Subjects

  • Dynamics of drops and films of nematic liquid crystals [79,80], liquid crystals close to nematic-isotropic transition
  • Films of active liquids, dynamics of adhesion/locomotion, tissue spreading
  • Large-scale continuation techniques for multi-field long-wave equations
  • Phase-field crystal models for crystalisation in evaporating suspensions
  • Dynamics of wetting transitions of binary and ternary systems

Active Subjects

  • Phase Field Crystal models for one- and two-component colloidal systems and their relation to standard model equations for pattern formation (Swift-Hohenberg Equation) [69,71,76]
  • Dynamical models for bacterial carpets [88,p17,97], biofilms [99] and active crystals [101]
  • Hybrid micro-meso models for contact lines of simple and complex liquids, e.g., via parameter passing from Molecular Dynamics [75] or Density Functional Theory [94,105] to mesoscopic hydrodynamics [104]. Also comparison of Kinetic Monte Carlo and mesoscopic hydrodynamics [106].
  • Patterned deposition in Langmuir-Blodgett transfer (substrate mediated condensation) [66,89], dip coating [93,103] and for drying suspensions and solutions [53,62,70]. Partial reviews in [84,93].
  • Morphological Transitions of Sliding Drops - Dynamics and Bifurcations [100].
  • Thermodynamic consistent description of the dynamics of free-interface films with solutes or surfactants (cases of high concentration, phase separating surfactants, nearby solid surface) [64,72,81,92,102], applied to experiment e.g., in [78,96].
  • (Dynamical) Density Functional Theory for drops at walls [82,94,105], driven interacting colloidal particles in nano-pores [63], cluster coarsening [87], solidification fronts [91,p16],
  • Depinning of driven drops: Various depinning mechanisms (Hopf vs. sniper vs. homoclinic bifurcation) [35,36,49,51,55,61,73]. Relation to drops on rotating cylinder [58,98].
  • Structure formation in films of fluids or diffusing molecules: Competition of different ruture mechanisms in the dewetting of simple liquids -- spinodal dewetting vs. nucleation [8,9,13,21,55]; the long-wave Marangoni instability [19,22]; effects of evaporation [52,65,90]; relation to epitaxial growth [52]; dragged films and dynamic wetting transitions [85,86]; ridge instabilities [20,95,106]; terrassed spreading [104].
  • Application of path-continuation methods to (active) fluid and soft matter systems [83], singularity solutions [77], tutorials on CeNoS website

Past Subjects

  • Transport in nano-pores: Depinning transitions for and ratcheting of driven interacting colloidal particles in heterogeneous nano-pores [63]
  • Dewetting of polymer mixtures: Coupling of decomposition of mixture and evolution of film surface profile [41,48,59,68]
  • Dewetting of nanoparticle suspensions: Deposition patterns resulting from the process of evaporative dewetting of a nanoparticle suspension [40,44-46,53,57] or a macromolecular solution [2-4]. Theory: kinetic Monte Carlo [40,45,46], Dynamical Density Functional theory [50,53], Thin film hydrodynamics [53,62,64,70].
  • Climbing vibrated droplets: Analysis of a self-ratcheting mechanism [54,56,74] and other vibration effects on thin film flow [31]. Relation to Fokker-Planck description for particle ratchets [56]. See also the Overview (in german) in the Physik Journal of February 2013 [p12].
  • Electric field induced interfacial instabilities [29,38,43,51,67]; Ratchet-induced micro-fluidic transport [38,43,56]
  • Dynamic domain formation in membranes: Thickness modulation induced phase separation [24].
  • Film instability and flow on heated substrates: Long-wave Marangoni instability on horizontal [19,22] and inclined [22] substrates. Instability modes, non-linear structures, coarsening. As well some interest in heterogeneously heated substrates [16,17].
  • Reactive surfactants: Interaction of thin film hydrodynamics and reaction-diffusion system [37,39,42].
  • Chemically driven running droplets: Several models for different experimental settings [23,30].
  • Sliding droplets, falling films and front instabilities: Dynamic wetting transition in a precursor film model [10,14], front instabilities [18], drops and films on a heated plate [22] and the validity domain of the Benney equation [27].
  • Wetting of textured surfaces [12].
  • Dewetting of two-layer films: Different rupture and coarsening pathways [26,28,34,54].
  • Two-layer films in a closed geometry: Various linear instabilities, non-linear behaviour and coarsening [29].
  • Film flow on a porous substrate: Various linear instability and non-linear behaviour in their dependence on porosity and layer thickness [47].
  • Dewetting of ultrathin films of simple liquids on heterogeneous horizontal substrates, including influence of noise, and stabilisation of Plateau Rayleigh instability by the heterogeneity [15,20]
  • Reaction-Diffusion systems: Surface reactions on anisotropic substrates [6,7,11]
  • Dewetting of thin film of aqueous collagen solution [2-4].
  • Stochastic geometry of polygonal networks applied to the hexagon-square-transition in Rayleigh-Bénard convection [5]


For more information move mouse over picture. Click on picture to obtain corresponding paper.

Binary Phase Field Crystal modelBinary Phase Field
Crystal model: transition of crystal structure with changing composition



Line deposition Deposition patterns -
morphological diagram



Depinning of driven colloidal particlesbifurcation diagram for regular dewetting patterns



Dewetting patterns bifurcation diagram for regular dewetting patterns



Evaporative dewetting of nanoparticle suspensionEvaporative dewetting of nanoparticle suspension



Gradient dynamics formulations for layers of solutions/suspensionsGradient dynamics formulations for solutions/suspensions



Depinning ridges and dropsStability diagram for depinning
ridges and drops



Front snaking in Langmuir-Blodgett transfer close to a phase transitionFront snaking in Langmuir-Blodgett
transfer close to a phase transition




 
 
 
 
 

Last change:
ut 20.04.2017