Pressure of Active Matter
Active matter? Some examples:
Self-propelled colloidal particles Swimming Cells
Shaken Grains
What is the Pressure of an Active particle fluid? Does it behave like an equilibrium system?
A. P. Solon, J. Stenhammar, R. Wittkowski, M. Kardar, Y. Kafri, M. E. Cates, J. Tailleur, Phys. Rev. Lett. 114, 198301 (2015);
A. P. Solon, Y. Fily, A. Baskaran, M. E. Cates, Y. Kafri, M. Kardar, J. Tailleur, Nature Phys. 11, 673 (2015)
Two common models are Run and Tumble Paticles (RTP), and Active Brownian Particles (ABP):
Force and pressure can be measured by introducing a wall potential:
Reorientation of an active particle close to the wall needs to be separately specified:
Pressure depends on the wall potential - No equation of state!
For non-interacting ellipses, pressure decreases whe the torque increases:
There is a net force on a closed box. (Note that there is no momentum conservation.)
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