TY - JOUR
T1 - Mechanical pressure and momentum conservation in dry active matter
AU - Fily, Y.
AU - Kafri, Yariv
AU - Solon, A. P.
AU - Tailleur, J.
AU - Turner, Ari mark
N1 - Funding Information: We thank M Cates, M Kardar, A Morozov, J Stenhammar for discussions. YF was supported by the NSF, award DMR-1149266, the Brandeis Center for Bioinspired Soft Materials, an NSF MRSEC, award DMR-1420382, and the W M Keck Foundation. YF’s computational resources were provided by the NSF through XSEDE, award TG-MCB090163, and the Brandeis HPCC. YK is supported by an I-CORE Program of the Planning and Budgeting Committee of the Israel Science Foundation and an Israel Science Foundation grant. AS is funded by the Betty and Gordon Moore foundation. JT was supported by ANR grants Bactterns. JT and YK acknowledge the support of a shared CNRS-MOST travel grant. Publisher Copyright: © 2017 IOP Publishing Ltd Printed in the UK.
PY - 2017/12/19
Y1 - 2017/12/19
N2 - We relate the breakdown of equations of states (EOS) for the mechanical pressure of generic dry active systems to the lack of momentum conservation in such systems. We show how net sources and sinks of momentum arise generically close to confining walls. These typically depend on the interactions of the container with the particles, which makes the mechanical pressure a container-dependent quantity. We show that an EOS is recovered if the dynamics of the propulsive forces of the particles are decoupled from other degrees of freedom and lead to an apolar bulk steady-state. This recovery of an EOS stems from the mean steady-state active force density being the divergence of the flux of 'active impulse', an observable which measures the mean momentum particles will receive from the substrate in the future.
AB - We relate the breakdown of equations of states (EOS) for the mechanical pressure of generic dry active systems to the lack of momentum conservation in such systems. We show how net sources and sinks of momentum arise generically close to confining walls. These typically depend on the interactions of the container with the particles, which makes the mechanical pressure a container-dependent quantity. We show that an EOS is recovered if the dynamics of the propulsive forces of the particles are decoupled from other degrees of freedom and lead to an apolar bulk steady-state. This recovery of an EOS stems from the mean steady-state active force density being the divergence of the flux of 'active impulse', an observable which measures the mean momentum particles will receive from the substrate in the future.
KW - Active matter
KW - Pressure
KW - Statistical mechanics
UR - https://www.scopus.com/pages/publications/85041310894
U2 - 10.1088/1751-8121/aa99b6
DO - 10.1088/1751-8121/aa99b6
M3 - Article
SN - 1751-8113
VL - 51
JO - Journal of Physics A: Mathematical and Theoretical
JF - Journal of Physics A: Mathematical and Theoretical
IS - 4
M1 - 044003
ER -