title: Comparison between Smoluchowski and Boltzmann approaches for self-propelled rods.
abstract: Considering systems of self-propelled polar particles with nematic interactions ("rods"), we compare the continuum equations describing the evolution of polar and nematic order parameters, derived either from Smoluchowski or Boltzmann equations. Our main goal is to understand the discrepancies between the continuum equations obtained so far in both frameworks. We first show that, in the simple case of point-like particles with only alignment interactions, the continuum equations obtained have the same structure in both cases. We further study, in the Smoluchowski framework, the case where an interaction force is added on top of the aligning torque. This clarifies the origin of the additional terms obtained in previous works. Our observations lead us to emphasize the need for a more involved closure scheme than the standard normal form of the distribution when dealing with active systems.
authors.affiliation: Université Grenoble Alpes, LIPHY, F-38000 Grenoble, France.|CNRS, LIPHY, F-38000 Grenoble, France.
authors.forename: Eric
authors.initials: E
authors.lastname: Bertin
authors.affiliation: Department of Physics, Brandeis University, Waltham, Massachusetts 02474, USA.
authors.forename: Aparna
authors.initials: A
authors.lastname: Baskaran
authors.affiliation: Service de Physique de l'Etat Condensé, CNRS UMR 3680, CEA-Saclay, 91191 Gif-sur-Yvette, France.|Beijing Computational Science Research Center, Beijing 100094, China.
authors.forename: Hugues
authors.initials: H
authors.lastname: Chaté
authors.affiliation: Department of Physics, Syracuse University, Syracuse, New York 13244, USA.|Syracuse Biomaterials Institute, Syracuse University, Syracuse, New York 13244, USA.
authors.forename: M Cristina
authors.initials: MC
authors.lastname: Marchetti
mesh_terms: D057446:Hydrodynamics; D008962:Models, Theoretical; D009038:Motion