Active Casimir image


Active Matter

Active matter is a growing field spanning soft matter, biological physics, and statistical mechanics. Active matter systems are intrinsically nonequilibrium and can exhibit transitions between motility-induced cluster and uniform liquid phases as a function of density and activity. Most studies of active matter have focused on systems with a smooth substrate, but soft matter systems interacting with disordered pinning substrates are known to exhibit a variety of order-disorder transitions. An open question is what happens when active matter systems are coupled to structured substrates. We use numerical simulations to examine the dynamics of active run-and-tumble disks moving and/or driven through a variety of structured environments.

Preprints:

  1. Analytical model for the motion and interaction of two-dimensional active nematic defects
    C.D. Schimming, C.J.O. Reichhardt, and C. Reichhardt
    We develop an approximate, analytical model for the velocity of defects in active nematics by combining recent results for the velocity of topological defects in nematic liquid crystals with the flow field generated from individual defects in active nematics. Importantly, our model takes into account the long-range interactions between defects that result from the flows they produce as well as the orientational coupling between defects inherent in nematics. We show that the model can analytically predict bound states between two +1/2 winding number defects, effective attraction between two −1/2 defects, and the scaling of a critical unbinding length between ±1/2 defects with activity. The model also gives predictions for the trajectories of defects, such as the scattering of +1/2 defects by −1/2 defects at a critical impact parameter that depends on activity. In the presence of circular confinement, the model predicts a braiding motion for three +1/2 defects that was recently seen in experiments. arXiv


Papers:

  1. Active nematic ratchet in asymmetric obstacle arrays
    C.D. Schimming, C.J.O. Reichhardt, and C. Reichhardt
    Phys. Rev. E 109, 064602 (2024). arXiv


  2. Phase separation, edge currents, and Hall effect for active matter with Magnus dynamics
    B. Adorjani, A. Libal, C. Reichhardt, and C.J.O. Reichhardt
    Eur. Phys. J. E 47, 40 (2024). arXiv


  3. Motility induced phase separation and frustration in active matter swarmalators
    B. Adorjani, A. Libal, C. Reichhardt, and C.J.O. Reichhardt
    Phys. Rev. E 109, 024607 (2024). arXiv


  4. Vortex lattices in active nematics with periodic obstacle arrays
    C.D. Schimming, C.J.O. Reichhardt, and C. Reichhardt
    Phys. Rev. Lett. 132, 018301 (2024). arXiv


  5. Characterizing different motility induced regimes in active matter with machine learning and noise
    D. McDermott, C. Reichhardt, and C.J.O. Reichhardt
    Phys. Rev. E 108, 064613 (2023). arXiv


  6. Dynamic phases and combing effects for elongated particles moving over quenched disorder
    A. Libal, S. Stepanov, C. Reichhardt, and C.J.O. Reichhardt
    Soft Matter 19, 7937 (2023). arXiv


  7. Transient pattern formation in an active matter contact poisoning model
    P. Forgacs, A. Libal, C. Reichhardt, N. Hengartner, and C.J.O. Reichhardt
    Commun. Phys. 6, 294 (2022). arXiv


  8. Friction mediated phase transition in confined active nematics
    C.D. Schimming, C.J.O. Reichhardt, and C. Reichhardt
    Phys. Rev. E 108, L012602 (2023). arXiv


  9. Pattern formation and transport for externally driven active matter on periodic substrates
    C. Reichhardt and C.J.O. Reichhardt
    EPL 142, 37001 (2023). arXiv


  10. Transition from susceptible-infected to susceptible-infected-recovered dynamics in a susceptible-cleric-zombie-recovered active matter model
    A. Libal, P. Forgacs, A. Neda, C. Reichhardt, N. Hengartner, and C.J.O. Reichhardt
    Phys. Rev. E 107, 024604 (2023). arXiv


  11. Pattern formation and flocking for particles near the jamming transition on resource gradient substrates
    L. Varga, A. Libal, C. Reichhardt, and C.J.O. Reichhardt
    Phys. Rev. E 106, 064602 (2022). arXiv


  12. Future directions for active matter on ordered substrates
    C. Reichhardt, A. Libal, and C.J.O. Reichhardt
    EPL 139, 27001 (2022). arXiv


  13. Using active matter to introduce spatial heterogeneity to the susceptible infected recovered model of epidemic spreading
    P. Forgacs, A. Libal, C. Reichhardt, N. Hengartner, and C.J.O. Reichhardt
    Sci. Rep. 12, 11229 (2022). arXiv


  14. Active rheology in odd viscosity systems
    C.J.O. Reichhardt and C. Reichhardt
    EPL 137, 66004 (2022). arXiv


  15. Active regimes for particles on resource landscapes
    L. Varga, A. Libal, C.J.O. Reichhardt, and C. Reichhardt
    Phys. Rev. Res. 4, 013061 (2022). arXiv


  16. Crystals break up with a twist
    C.J.O. Reichhardt and C. Reichhardt
    Nature Phys.18, 134 (2022).


  17. Active matter shepherding and clustering in inhomogeneous environments
    P. Forgacs, A. Libal, C. Reichhardt, and C.J.O. Reichhardt
    Phys. Rev. E 104, 044613 (2021). arXiv


  18. An exceptional view of phase transitions in non-equilibrium systems
    C.J.O. Reichhardt and C. Reichhardt
    Nature 592, 363 (2021).


  19. Clogging, dynamics and reentrant fluid for active matter on periodic substrates
    C. Reichhardt and C.J.O. Reichhardt
    Phys. Rev. E 103, 062603 (2021). arXiv


  20. Active matter commensuration and frustration effects on periodic substrates
    C. Reichhardt and C.J.O. Reichhardt
    Phys. Rev. E 103, 022602 (2021). arXiv


  21. Directional locking effects for active matter particles coupled to a periodic substrate
    C. Reichhardt and C.J.O. Reichhardt
    Phys. Rev. E 102, 042616 (2020). arXiv

  22. Active microrheology, Hall effect, and jamming in chiral fluids
    C. Reichhardt and C.J.O. Reichhardt
    Phys. Rev. E 100, 012604 (2019). arXiv

  23. Reversibility, pattern formation and edge transport in active chiral and passive disk mixtures
    C. Reichhardt and C.J.O. Reichhardt
    J. Chem. Phys. 150, 064905 (2019). arXiv

  24. Laning and clustering transitions in driven binary active matter systems
    C. Reichhardt, J. Thibault, S. Papanikolau, and C.J.O. Reichhardt
    Phys. Rev. E 98, 022603 (2018). arXiv

  25. Clogging and depinning of ballistic active matter systems in disordered media
     C. Reichhardt and C.J.O. Reichhardt
    Phys. Rev. E 97, 052613 (2018). arXiv

  26. Avalanche dynamics for active matter in heterogeneous media
     C.J.O. Reichhardt and C. Reichhardt
    New J. Phys. 20, 025002 (2018). arXiv


  27. Negative differential mobility and trapping in active matter systems
     C. Reichhardt and C.J.O. Reichhardt
    J. Phys.: Condens. Matter 30, 015404 (2018). arXiv


  28. Dewetting and spreading transitions for active matter on random pinning substrates
     Cs. Sandor, A. Libal, C. Reichhardt, and C.J. Olson Reichhardt,
    J. Chem. Phys. 146, 204903 (2017). arXiv


  29. Dynamic phases of active matter systems with quenched disorder
     Cs. Sandor, A. Libal, C. Reichhardt, and C.J. Olson Reichhardt,
    Phys. Rev. E 95, 032606 (2017). arXiv


  30. Ratchet effects in active matter systems (invited review)
    C.J. Olson Reichhardt and C. Reichhardt,
    Ann. Rev. Condens. Matt. Phys. 8, 51 (2017). arXiv


  31. Collective transport for active matter run-and-tumble disk systems on a traveling-wave substrate
     Cs. Sandor, A. Libal, C. Reichhardt, and C.J. Olson Reichhardt,
    Phys. Rev. E 95, 012607 (2017). arXiv


  32. Collective motion: Disorder in the wild
    C.J. Olson Reichhardt and C. Reichhardt,
    Nature Phys. 13, 10 (2017).


  33. Collective ratchet effects and reversals for active matter particles on quasi-one-dimensional asymmetric substrates
     D. McDermott, C.J. Olson Reichhardt, and C. Reichhardt,
    Soft Matter 12, 8606 (2016). arXiv


  34. Active microrheology in active matter systems: Mobility, intermittency, and avalanches
    C. Reichhardt and C.J. Olson Reichhardt,
    Phys. Rev. E 91, 032313 (2015). arXiv


  35. Absorbing phase transitions and dynamic freezing in running active matter systems
    C. Reichhardt and C.J. Olson Reichhardt,
    Soft Matter 10, 7502 (2014). arXiv


  36. Active matter transport on complex substrates
    C.J. Olson Reichhardt, D. Ray, and C. Reichhardt,
    Proc. SPIE 9164, Optical Trapping and Optical Micromanipulation XI, 91641N (2014).


  37. Casimir effect in active matter systems
    D. Ray, C. Reichhardt and C.J. Olson Reichhardt,
    Phys. Rev. E 90, 013019 (2014). arXiv


  38. Active matter transport and jamming on disordered landscapes
    C. Reichhardt and C.J. Olson Reichhardt,
    Phys. Rev. E 90, 012701 (2014). arXiv


  39. Active matter ratchets with an external drift
    C. Reichhardt and C.J. Olson Reichhardt,
    Phys. Rev. E 88, 062310 (2013). arXiv


  40. Dynamics and separation of circularly moving particles in asymmetrically patterned arrays
    C. Reichhardt and C.J. Olson Reichhardt
    Phys. Rev. E 88, 042306 (2013). arXiv


  41. Self-driven particles on asymmetric trap arrays
    L.M. Lopatina, C. Reichhardt, and C.J. Olson Reichhardt,
    Proc. SPIE 8810, Optical Trapping and Optical Micromanipulation X, 881016 (2013).


  42. Dynamics of self-driven and flocking particles on periodic arrays
    J.A. Drocco, L.M. Lopatina, C. Reichhardt, and C.J. Olson Reichhardt,
    Proc. SPIE 8458, Optical Trapping and Optical Micromanipulation IX, 84581I (2012).


  43. Bidirectional sorting of flocking particles in the presence of asymmetric barriers
    J.A. Drocco, C.J. Olson Reichhardt, and C. Reichhardt,
    Phys. Rev. E 85, 056102 (2012). arXiv


  44. Dynamical freezing of active matter
    C. Reichhardt and C.J. Olson Reichhardt,
    Proc. Natl. Acad. Sci. (USA) 108, 19099 (2011).


  45. Active matter on asymmetric substrates
    C.J. Olson Reichhardt, J. Drocco, T. Mai, M.B. Wan, and C. Reichhardt,
    Proc. SPIE 8097, Optical Trapping and Optical Micromanipulation VIII, 80970A (2011). arXiv


  46. Rectification of swimming bacteria and self-driven particle systems by arrays of asymmetric barriers
    M.B. Wan, C.J. Olson Reichhardt, Z. Nussinov, and C. Reichhardt,
    Phys. Rev. Lett. 101, 018102 (2008). arXiv


  47. Cooperative behavior and pattern formation in mixtures of driven and nondriven colloidal assemblies
     C. Reichhardt and C.J. Olson Reichhardt
    Phys. Rev. E 74, 011403 (2006). arXiv

Last modified Jan 7, 2019