The talk **On Modelling and Numerical Aspects of Fluid Model of Crystal Plasticity**, by Piotr Minakowski (University of Warsaw), will be held on Monday April 14, 2014 at 8:30 in room K4. After that, Vit Orava will talk about his recent work with a presentation entitled **On the heterogeneous catalysis in reactors **. Finally, PhD students from group B (Marek Čapek, Martin Michálek and Josef Žabenský) will do a short progress report of the actual status of their research.

**Abstract of the talk**

Looking at severe plastic deformation experiments, it seems that crystalline materials at yield behave as a special kind of anisotropic, highly viscous fluids flowing through an adjustable crystal lattice space. High viscosity provides a possibility to describe the flow as a quasi-static process, where inertial and other body forces can be neglected. The flow through the lattice space is restricted to preferred crystallographic planes and directions causing anisotropy. In the deformation process the lattice is strained and rotated. The proposed model is based on the rate form of the decomposition rule: the velocity gradient consists of the lattice velocity gradient and the sum of the velocity gradients corresponding to the slip rates of individual slip systems. The proposed crystal plasticity model allowing for large deformations is treated as the flow-adjusted boundary value problem.

In the talk I will compare two ways of derivation of such model, employing the Helmholtz and the Gibbs potentials. As a test example I analyze a plastic flow of an single crystal compressed in a channel die. For a numerical solution we employ the Updated Lagrangian and Arbitrary Lagrangian Eulerian (ALE) methods.

**Abstract of the PhD presentation**

We investigate modelling and analysis of the systems describing a heterogeneous catalysis in reactors. Exploiting mixture theory (Class I model) we derive a system of 3 equations in a bulk and 3 equations on a surface of the reactor. Furthermore, we discuss various forms of chemical processes such as surface reactions and sorption terms. Finally, we prove existence, uniqueness and maximum principle of the systems.