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Do hydrodynamic interactions affect the swim pressure?

Burkholder, Eric W. and Brady, John F. (2018) Do hydrodynamic interactions affect the swim pressure? Soft Matter, 14 (18). pp. 3581-3589. ISSN 1744-683X. doi:10.1039/c8sm00197a.

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We study the motion of a spherical active Brownian particle (ABP) of size a, moving with a fixed speed U0, and reorienting on a time scale τ_R in the presence of a confining boundary. Because momentum is conserved in the embedding fluid, we show that the average force per unit area on the boundary equals the bulk mechanical pressure P∞ = p∞_f + Π∞, where p∞_f is the fluid pressure and Π∞ is the particle pressure; this is true for active and passive particles alike regardless of how the particles interact with the boundary. As an example, we investigate how hydrodynamic interactions (HI) change the particle-phase pressure at the wall, and find that Π^(wall) = n∞(k_BT+ ζ(Δ)U_0ℓ(Δ)/6), where ζ is the (Stokes) drag on the swimmer, ℓ = U_0τ_R is the run length, and Δ is the minimum gap size between the particle and the wall; as Δ → ∞ this is the familiar swim pressure [Takatori et al., Phys. Rev. Lett., 2014, 113, 1–5].

Item Type:Article
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Burkholder, Eric W.0000-0001-7420-4290
Brady, John F.0000-0001-5817-9128
Additional Information:© 2018 The Royal Society of Chemistry. The article was received on 27 Jan 2018, accepted on 08 Apr 2018 and first published on 10 Apr 2018. Conflicts of interest: There are no conflicts to declare.
Issue or Number:18
Record Number:CaltechAUTHORS:20180423-105343832
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:86010
Deposited By: Tony Diaz
Deposited On:25 Apr 2018 18:07
Last Modified:15 Nov 2021 20:34

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