[Soft-matter] Soft Matter & Complex Systems Seminar on 11 Oct 2024

[Maciej Lisicki]

Dear all,

Apologies for the typographic error - the seminar of A. Vilfan is on Friday 11 October. 

> On 6 Oct 2024, at 21:46, Maciej Lisicki <Maciej.Lisicki at fuw.edu.pl> wrote:
> 
> Dear Soft Matter & Complex Systems Colleagues and Friends,
> 
> 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 
> 
> Andrej Vilfan (J. Stefan Institute, Ljubljana, Slovenia)
> 
> will give a talk
> Minimum dissipation theorems for microswimmers
> 
> Abstract
> 
> 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.
> 
> [1] B. Nasouri, A. Vilfan and R. Golestanian, Phys. Rev. Lett., 126,034503 (2021)
> [2] A. Daddi-Moussa-Ider, R. Golestanian and A. Vilfan, Nat. Commun.14, 6060 (2023)
> [3] A. Daddi-Moussa-Ider, R. Golestanian and A. Vilfan, J. Fluid Mech.986, A32 (2024)
> 
> We warmly welcome everyone to attend the talk and the Soft Matter Coffee Break after the seminar, held in room 2.63 (2nd floor).
> 
> Maria Ekiel-Jeżewska
> Maciej Lisicki
> Piotr Szymczak
> Panagiotis Theodorakis
> Marek Trippenbach
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