Hauptseminar Soft Matter SS 2019/Modelling and simulation of catalytically driven particles

"{{{number}}}" is not a number.

Date

2019-07-12

Time

14:00

Topic

Modelling and simulation of catalytically-driven particles

Speaker

Jan Finkbeiner

Tutor

Michael Kuron

Handout

[1]

}}

Contents

In this talk, a continuum method for the treatment of electrokinetics will be introduced. When combined with a simple scheme for chemical reactions, this allows for the treatment of chemically-propelled swimmers. Electrokinetics refers to the coupled occurence of hydrodynamics and diffusion, advection and migration of dissolved chemical species. Thanks to a separation of time scales, many systems do not need explicit treatment neither of water nor of solutes and computational efficiency can therefore be gained by discretizing the continuum equations on a lattice.

For hydrodynamics, the lattice-Boltzmann method, discussed in a previous topic, can be used. For diffusion-advection-migration, the lattice electrokinetics method by Capuani et al. is the method of choice. By adding a simple scheme based on the stoichiometric coefficients and rate constant of a chemical reaction, the propulsion can be described as a flux boundary condition for the diffusion-advection-migration scheme.

First, the underlying system of continuum equations, often referred to as Poisson-Nernst-Planck, is introduced. This includes Fick's diffusion equation and Poisson's equation for electrostatics. Second, the discretization by Capuani et al. is constructed and it is shown that applicable in the same limit as Poisson-Boltzmann. Finally, the application to the study of individual and multiple swimmers is sketched out and some results are summarized.

Literature

• Kirby, Brian J..
  "Micro- and Nanoscale Fluid Mechanics: Transport in Microfluidic Devices".
  Cambridge University Press, 2010.
  [DOI] [URL]
• Capuani, Fabrizio and Pagonabarraga, Ignacio and Frenkel, Daan.
  "Discrete solution of the electrokinetic equations".
  The Journal of Chemical Physics 121(973–986), 2004.
  [PDF] (592 KB) [DOI]
• Rempfer, Georg and Davies, Gary B. and Holm, Christian and de Graaf, Joost.
  "Reducing spurious flow in simulations of electrokinetic phenomena".
  The Journal of Chemical Physics 145(4)(044901), 2016.
  [PDF] (4 MB) [DOI]
• Michael Kuron.
  "Efficient Lattice Boltzmann Algorithms for Colloids Undergoing Electrophoresis".
  Master's thesis, University of Stuttgart, 2015.
  
• Michael Kuron and Georg Rempfer and Florian Schornbaum and Martin Bauer and Christian Godenschwager and Christian Holm and Joost de Graaf.
  "Moving charged particles in lattice Boltzmann-based electrokinetics".
  The Journal of Chemical Physics 145(21)(214102), 2016.
  [PDF] (718 KB) [DOI]
• Brown, Aidan T. and Poon, Wilson C. K..
  "Ionic effects in self-propelled Pt-coated Janus swimmers".
  Soft Matter 10(22)(4016–4027), 2014.
  [PDF] (2 MB) [DOI]
• Brown, Aidan T. and Poon, Wilson C. K. and Holm, Christian and de Graaf, Joost.
  "Ionic screening and dissociation are crucial for understanding chemical self-propulsion in polar solvents".
  Soft Matter 13(1200–1222), 2017.
  [PDF] (5 MB) [DOI]
• Kuron, Michael and Kreissl, Patrick and Holm, Christian.
  "Toward Understanding of Self-Electrophoretic Propulsion under Realistic Conditions: From Bulk Reactions to Confinement Effects".
  Accounts of Chemical Research 51(12)(2998–3005), 2018.
  [PDF] (4 MB) [DOI]
• Solovev, Alexander A and Mei, Yongfeng and Bermúdez Ure\ na, Esteban and Huang, Gaoshan and Schmidt, Oliver G.
  "Catalytic microtubular jet engines self-propelled by accumulated gas bubbles".
  Small 5(14)(1688–1692), 2009.