Title: Extending Granular Resistive Force Theory to Model Plant Uprooting

Author (Table Talk): Lale Yilmaz, Massachusetts Institute of Technology

Abstract:

Modeling plants resistance to uprooting and their contribution to ground stability requires accounting for the constitutive response of both the plant and its surrounding environment. This can become computationally costly when a large plant or multiple plant systems are considered. The computational cost can be reduced by solving for the physical response of the terrain via granular resistive force theory (gRFT). Granular RFT is a reduced order model which can successfully model the motion of rigid intruders in granular media with a reduced computational cost. To calculate a traction experienced by the intruder due to the surrounding granular medium, gRFT requires the direction of velocity as an input along with other kinematic and material parameters. This fundamental dependence of gRFT on the direction of velocity renders gRFT ineffective at modeling stagnant scenarios where an intruder, or a portion of it is not moving. With the present work, we extend the functionality of granular RFT to include stagnant cases, naming this new version as elastic RFT (eRFT). This is done by defining an elastic traction provided by the granular material prior to its yield and flow. Pairing elastic RFT with flexible roots modeled as nonlinear elastic beams, we model primitive plant structures' response to uprooting. We showcase the validity of eRFT results through comparisons with experimental data and higher order simulations.