<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div dir="ltr"><meta http-equiv="content-type" content="text/html; charset=utf-8">Dear all,<div><br></div><div>Apologies for the typographic error - the seminar of A. Vilfan is on Friday 11 October. </div><div><div dir="ltr"><br><blockquote type="cite">On 6 Oct 2024, at 21:46, Maciej Lisicki <Maciej.Lisicki@fuw.edu.pl> wrote:<br><br></blockquote></div><blockquote type="cite"><div dir="ltr"><meta http-equiv="content-type" content="text/html; charset=utf-8"><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><div style="font-family: HelveticaNeue;"><font face="HelveticaNeue">On Friday 4 October 2024 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="font-family: HelveticaNeue;"><font face="HelveticaNeue"><br></font></div><div style="margin: 0px; font-stretch: normal; line-height: normal; min-height: 14px;"><font face="HelveticaNeue" style="font-family: HelveticaNeue;"><b>Andrej Vilfan </b></font><font face="HelveticaNeue">(J. Stefan Institute, Ljubljana, Slovenia)</font></div><div style="font-family: HelveticaNeue; margin: 0px; font-stretch: normal; line-height: normal; min-height: 14px;"><font face="HelveticaNeue"><br></font></div><div style="font-family: HelveticaNeue; 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;"><div><h2 style="margin: 6px 0px 12px; padding: 0px;"><font face="HelveticaNeue"><span style="font-size: 12px;">Minimum dissipation theorems for microswimmers</span></font></h2></div><h2 style="font-family: HelveticaNeue; margin: 6px 0px 12px; padding: 0px; caret-color: rgb(68, 68, 68);"><b><font face="HelveticaNeue" style="font-size: 12px;">Abstract</font></b></h2><div><div><font face="HelveticaNeue">Microswimmers are natural or artificial self-propelled microscaleobjects moving through a fluid at low Reynolds numbers. The entropyproduction of microswimmers, related to their dissipated power,consists of two contributions. The external dissipation takes place inthe viscous fluid surrounding the microswimmer. Internal dissipationtakes place in the propulsive layer on the swimmer's surface. We haveshown that a lower bound on the external dissipation can be derivedwith the knowledge of drag coefficients of two bodies of the sameshape, one with a no-slip and one with a perfect slip boundarycondition [1]. This approach can be generalized to take into accountthe internal dissipation, which is often the dominant contribution. Bycombining the Helmholtz minimum dissipation theorem and the principleof linear superposition, we solve the combined minimum dissipationproblem for different classes of swimmers including surface-drivenviscous droplets, Marangoni surfers, etc. [2,3]. We show that theminimum entropy production in suspensions of active microswimmersdiffers fundamentally from particles driven by external forces.</font></div><div><br></div><div><font face="HelveticaNeue">[1] B. Nasouri, A. Vilfan and R. Golestanian, Phys. Rev. Lett., 126,034503 (2021)</font></div><div><font face="HelveticaNeue">[2] A. Daddi-Moussa-Ider, R. Golestanian and A. Vilfan, Nat. Commun.14, 6060 (2023)</font></div><div><font face="HelveticaNeue">[3] A. Daddi-Moussa-Ider, R. Golestanian and A. Vilfan, J. Fluid Mech.986, A32 (2024)</font></div></div><div style="font-family: HelveticaNeue;"><br></div></div><div style="font-family: HelveticaNeue; 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></div></blockquote></div></div></body></html>