Shear localisation with 2D Viscous Froth and its relation to the Continuum Model 9 clearly quite noisy, presumably due to the small system size. To obtain a measure of the width of the flowing region from these noisy profiles, we use the following definition of localisation length, denoted by l$_{int}$ [27] This integral, which has the required dimensions of length, is calculated numerically for each of our velocity profiles using the Trapezoidal Rule. Fig. 7 shows a varia- tion of localisation length with λV . Note that for low λV we find large scatter in the localisation lengths, however, this scatter decreases as λV is increased. For high λV , the length converges towards the minimum localisation length, l$_{min}$ = ¯ A 1 / $^{2}$, the width of one bubble layer (see Fig. 6 The location of T1 topological changes as a function of strain for a polydisperse sample. After an initial transient, where T1s happen everywhere in the foam, the flow localises and T1s are found to occur mostly next to the moving bound- ary (at y = 10 ¯ A 1 / $^{2}$). Shown data is for Sample 1 where λV = 0 . 05 γ/ ¯ A 1 / 2 . Fig. 5 Examples of velocity profiles for different values of λV . Profiles shown are for Sample 1. The corresponding lo- calisation lengths for these profiles are denoted by filled cir- cles in Fig. 7. 0 2 4 6 8 10 Distance from moving boundary  [A $^{1/2}$] 0.2 0.4 0.6 0.8 1 Average bubble velocity V = 0.01  V = 0.025  V = 0.05  V = 0.1  0 0.05 0.1 0.15 0.2 0.25 0.3 V  [  / A $^{1/2}$] 2 4 6 8 10 Localisation Length l int [A 1/2$^{]}$ Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 0 2 4 6 8 10 Strain 2 4 6 8 10 y location of T1  [A 1/2$^{]}$ Fig. 7 Localisation lengths for a range of λV . Each symbol represents one simulation run. For low λV , there is a wide range of lengths, while for high λV , only the first layer of bubbles flows. Filled symbols indicate simulations where V is fixed and λ is varied. Open symbols indicate simulations where λ is fixed and V is varied. l$_{int}$ = 1 V ∫ L 0 v ( y ) dy . (8)