Physically-informed data-driven modeling of active nematics

A continuum description is essential for understanding variety of collective phenomena in active matter. However, building quantitative continuum models of active matter from first principles can be extremely challenging due to both the gaps in our knowledge and the complicated structure of nonlinear interactions. Here we use a novel physically-informed data-driven approach to construct a complete mathematical model of an active nematic from experimental data describing kinesin-drive microtubule bundles confined to an oil-water interface. We find that the structure of the model is similar to the Leslie-Erisken and Beris-Edwards models, but there are notable differences. Rather unexpectedly, elastic effects are found to play no role, with the dynamics controlled entirely by the balance between active stresses and highly anisotropic viscous stresses.

The movies below illustrate some key elements of our analysis and provide validation of the results. The code used to synthesize physical relations included in the model can be found on GitHub.

Experimental movie and divergence of the flow field	Experimental movie and the mask used to select reliable data
Observed and predicted angular velocity of the microtubules	Balance between active and viscous stresses
Comparison of experimental observations with the predictions of the model identified from data