<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body style="overflow-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;"><div style="font-family: HelveticaNeue;"><font face="HelveticaNeue">Dear Soft Matter & Complex Systems Colleagues and Friends,</font></div><div style="font-family: HelveticaNeue;"><font face="HelveticaNeue"><br></font></div><div style="font-family: HelveticaNeue;"><div><font face="HelveticaNeue">On Friday 8 December 2023 at 9:30 AM at the UW Faculty of Physics (Pasteura 5, Warsaw; room 1.40) we are hosting a seminar during which</font></div><div style="margin: 0px; font-stretch: normal; line-height: normal; min-height: 14px;"><b><br></b></div><div style="margin: 0px; font-stretch: normal; line-height: normal; min-height: 14px;"><font face="HelveticaNeue"><b>Bogdan Cichocki & Jeffrey Everts </b>(FUW</font>)</div><div style="margin: 0px; font-stretch: normal; line-height: normal; min-height: 14px;"><font face="HelveticaNeue"><br></font></div><div style="margin: 0px; font-stretch: normal; line-height: normal;"><font face="HelveticaNeue">will give a talk</font></div><div style="margin: 0px; font-stretch: normal; line-height: normal; min-height: 14px;"><span style="caret-color: rgb(68, 68, 68);"><br></span></div><div style="margin: 0px; font-stretch: normal; line-height: normal; min-height: 14px;"><div><b>Chiral active fluids in the creeping flow regime (Part II)</b></div><div><br></div><h2 style="margin: 6px 0px 12px; padding: 0px; caret-color: rgb(68, 68, 68);"><b style="font-size: 12px;">Abstract</b></h2><div>Viscosity is a property that tells us how easy it is to cause flow in a fluid. For incompressible isotropic systems, the most well-known type of viscosity is the shear viscosity, which quantifies how much of the fluid's available energy dissipates when a symmetric velocity gradient is induced into the system. However, the situation differs in so-called chiral active fluids, which are manifestly out-of-equilibrium systems. Here, the fluid particles are set into motion by activity or uniform rotation of the system and are, therefore, characterised by a non-trivial angular momentum density. Consequently, the flow properties of such a fluid are not just described by the shear viscosity. There are additional so-called odd viscosity coefficients that do not contribute to viscous dissipation in a direct manner.</div><div><br></div><div>Because of the fundamental interest in this problem and recent experiments, we study such chiral active fluids in the creeping flow regime in more detail. In Part 1 of the seminar (1 December), we show that the fundamental solution can be explicitly constructed without any approximation for stationary three-dimensional incompressible flow. Our calculations form the basis for solving more complicated flow problems and for constructing the theory of hydrodynamic interactions in chiral active fluids. In Part 2 of the talk (8 December), we will demonstrate how we can use the Green's function to construct an analytical exact solution for the single-particle problem. Furthermore, we will then explicitly demonstrate that odd viscosity can contribute to viscous dissipation via alteration of the fluid flow.</div></div><div style="margin: 0px; font-stretch: normal; line-height: normal;"><div style="margin: 0px; font-stretch: normal; line-height: normal;"><div style="margin: 0px; font-stretch: normal; line-height: normal;"><div style="margin: 0px; font-stretch: normal; line-height: normal;"><div style="margin: 0px; font-stretch: normal; line-height: normal;"><br></div></div></div></div></div><div style="margin: 0px; font-stretch: normal; line-height: normal;"><font face="HelveticaNeue">We warmly welcome everyone to attend the talk and the Soft Matter Coffee Break after the seminar, held in room 2.63 (2nd floor).</font></div></div><div style="font-family: HelveticaNeue;"><font face="HelveticaNeue"><br></font></div><div style="font-family: HelveticaNeue;"><div dir="auto" style="overflow-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;"><div style="margin: 0px; font-stretch: normal; line-height: normal;"><font face="HelveticaNeue">Maria Ekiel-Jeżewska</font></div><div style="margin: 0px; font-stretch: normal; line-height: normal;"><font face="HelveticaNeue">Maciej Lisicki</font></div><div style="margin: 0px; font-stretch: normal; line-height: normal;"><font face="HelveticaNeue">Piotr Szymczak</font></div><div style="margin: 0px; font-stretch: normal; line-height: normal;"><font face="HelveticaNeue">Panagiotis Theodorakis</font></div><div style="margin: 0px; font-stretch: normal; line-height: normal;"><font face="HelveticaNeue">Marek Trippenbach</font></div></div></div></body></html>