Shear localisation with 2D Viscous Froth and its relation to the Continuum Model 13 assumes that as V → 0, the velocity profile becomes approximately linear, then ˙ ϵ = V l , where l is the local- isation length. If we are on the lower bound, from eq. 19 we see that Δ = c$_{v}$ ( V l ) $^{a}$, or expressing it in a more convenient form, We are interested in the point where this line inter- sects the upper bound l $^{+}$( V ), which is given by eq. 16. We solve this pair of simultaneous equations (eq. 16, 21) in terms of V and choose to define the point of intersec- tion as our critical velocity V$_{c}$ (see Fig. 9). This yields We now proceed to relate the parameters of the (mi- croscopic) VF Model and the (macroscopic) Continuum Model. This is done using a combination of numerical and analytic approximations. To demonstrate preliminary evidence of existence of the stress overshoot in simulation, we have performed In one of the earliest publications on this subject, Kabla & Debregeas [17] attribute shear localisation in quasi-statics to what they call ‘self amplification’. This idea is qualitatively the same as the ideas presented in this section. This approach may have the capacity to explain other results in the literature, particularly [26] where shearing experiments are performed for an ordi- nary Bragg raft (where there are no confining plates) in a straight geometry. In these experiments (as in our VF simulations) variations in the averaged velocity pro- files are observed between experiments but averages over several experiments converge much better. Fig. 9 Results from a numerical solution of the Continuum Model incorporating the inequality given by eq. 19. For low V , there is a large range of possibilities for localisation length, while for high V , the range of allowed lengths converges to a narrow band. V$_{c}$ is our critical velocity below which a large range of localisation lengths is possible; see eq. 22. l $^{+}$( V ) and l $^{−}$( V ) denote the upper and lower bounds to the range of allowable solutions, respectively. To make a more quantitative comparison between continuum theory and the VF results presented in Sec. 4, a more detailed study of the relationship between the parameters of both models is required. We present such a study in the next section. V$_{c}$ = Δ a +1 a (1+ b ) $^{(}$a (1 + b ) 1 + a ) 1 1+ b ( 1 c$_{d}$ ( c$_{v}$ ) 1 a ) 1 1+ b . (22) l = ( c$_{v}$ Δ$^{)}$$^{1}$ a V . (21) 6 Relating the Continuum Model to the Viscous Froth Model 0 1 2 3 4 5 V 0.5 1 1.5 2 Localisation Length a=0.5 , b=1 , c$_{d}$=1, c$_{v}$=1 ,  V$_{c}$ l$^{+}$(V) l$^{-}$(V)