Fig. 2.

Comparison of shape-based and coarse-grained traction-based stress. (A–C) Solid state at $v_0=0.5$, $P_0=3.3$. (D–F) Liquid state at $v_0=0.5$, $P_0=3.8$. (A and D) Interaction normal stress ${\sigma }_n^{(i)int}$ calculated from the instantaneous cell shapes obtained from Eqs. 3a and 7. Red denotes positive (contractile) stress and blue negative (extensile) stress. (B and E) Interaction normal stress ${\sigma }_n^{(i)int}$ calculated using the coarse-grained traction-based mechanical inference by inverting Eq. 9 and using Eq. 3a. The arrows denote the traction forces. (C and F) The coarse-grained traction-based mechanical inference is validated by plotting the traction-based stress against the shape-based stress in the solid (C) and in the liquid (F) state. The data are for $400$ cells in a square box of side $L=20$ with $D_r=0.1$ and with periodic boundary condition.