Faculty of Physics University of Warsaw > Events > Seminars > Soft Matter and Complex Systems Seminar

Soft Matter and Complex Systems Seminar

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room 1.40, Pasteura 5 at 09:30

Piotr Zdybel (IFT UW)

Effective action and phase diagram of a model of superconductivity with population imbalance

Motivated by the growing number of high temperature superconductors characterized by quasi-two-dimensional layers structure, we investigate thermodynamic properties and the structure of the effective action in a model describing singlet superconductivity with population imbalance. The corresponding effective action is obtained within the path-integral formalism. We compute the mean-field phase diagram for the model.

room 1.40, Pasteura 5 at 09:30

Jacek Wojtkiewicz (KMMF UW)

Introduction to Bethe Ansatz (part II)

Some introductory informations concerning Bethe Ansatz technique will be given. An example how it works will be presented using XXZ Heisenbergone-half spin chain as an illustration.

room 1.40, Pasteura 5 at 09:30

Jacek Wojtkiewicz (KMMF UW)

Introduction to Bethe Ansatz (part I)

Some introductory informations concerning Bethe Ansatz technique will be given. An example how it works will be presented using XXZ Heisenbergone-half spin chain as an illustration.

room 1.40, Pasteura 5 at 09:30

Agnieszka Budek (IFT UW, IGF PAN)

Evolving network model of dissolution and precipitation in porous media

Chemical erosion of a porous medium is a complex process, involving the interplay between flow, transport, reaction and geometry evolution. The nonlinear couplings between these processes may lead to the formation of intricate dissolution patterns, the characteristics of which depend strongly on the fluid flow and mineral dissolution rates. In particular, in a broad range of physical conditions, long, finger-like channels or “wormholes” are spontaneously formed, where the majority of the flow is focused. To study this process, we model the porous medium as a system of interconnected pipes with the diameter of each segment increasing in proportion to the local reactant consumption. Moreover, the topology of the network is allowed to change dynamically during the simulation: as the diameters of the eroding pores become comparable with the interpore distances, the pores are joined together thus changing the interconnections within the network. With this model, we investigate different growth regimes in an evolving porous medium, allowing for both erosion and precipitation of the dissolved material.

room 1.40, Pasteura 5 at 09:30

Karol Makuch (ICHF PAN)

Stokes law and Einstein viscosity coefficient in complex liquids

The Stokes law, which describes motion of particle in viscous liquid, and Einstein viscosity coefficient, which describes increase of viscosity when small amount of solid particles is added to viscous liquid, lie at the core of experiments probing hydrodynamic properties of immersed particles or liquid itself. We derive Stokes law and Einstein viscosity coefficient for complex liquids, in which viscosity is scale-dependent, i.e. it depends on wave vector in Fourier space. We also discover that the relation between calculated Stokes drag coefficient and Einstein coefficient is universal - it does not depend on the particular form of scale dependent viscosity, and is the same for all complex liquids.

room 1.40, Pasteura 5 at 09:30

Ryszard Kutner (IFD UW)

Dynamic bifurcations on financial markets

We provide evidence that catastrophic bifurcation breakdowns or transitions, preceded by early warning signs such as flickering phenomena, are present on notoriously unpredictable financial markets. For this we construct robust indicators of catastrophic dynamical slowing down and apply these to identify hallmarks of dynamical catastrophic bifurcation transitions. This is done using daily closing index records for the representative examples of financial markets of small and mid to large capitalisations experiencing a speculative bubble induced by the worldwide financial crisis of 2007/2008.
doi:10.1016/j.chaos.2016.03.005 Chaos, Solitons & Fractals 2015.

room 1.40, Pasteura 5 at 09:30

Paweł Żuk (IFT UW)

On the aggregation of suspensions in the shear flow (part II)

We investigate the process of aggregation of the suspension of weakly attractive spherical and rod-like particles under the shear flow. Both the morphology of the aggregates and the dynamics of the the aggregation process are considered for moderate volume fractions as a function of the shear rate. We show that various aspects of aggregation process exhibit universal behavior regardless of the monomer particle shape.

room 1.40, Pasteura 5 at 09:30

Jaromir Panas (IFT UW)

Bosonic Dynamical Mean-Field Theory – application for the Bose-Hubbard type models (part II)

Fast development of techniques and growing number of results of experiments with cold atoms in optical lattices create a growing demand for theoretical description of observed phenomena. The Bose-Hubbard model is well suited for this task. However, solving this model poses a formidable challenge in itself, and some approximation scheme is needed, such as dynamical mean-field theory. In my talk I present basic concepts of this method. I show how it compares to alternative approximation schemes. Finally I present our recent results for the Bose-Hubbard model extended by an infinite-range interaction term.

room 1.40, Pasteura 5 at 09:30

Paweł Żuk (IFT UW)

On the aggregation of suspensions in the shear flow

room 1.40, Pasteura 5 at 09:30

Jaromir Panas (IFT UW)

Bosonic Dynamical Mean-Field Theory – application for the Bose-Hubbard type models

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