Fig. 3
From: River-bed armouring as a granular segregation phenomenon
Evolution of coarse grain concentration and armour through time. a 1D (x-averaged) concentration map of large grains over time for shear stress \(\tau _s^* = 4.1\tau _{cs}^*\). The red dashed lines show the positions of the armour surface (z s a) and the bottom of the armored layer (z i ), which are used to calculate the thickness of the armored layer in Fig. 4a. b Same as a for the advection-diffusion model, using velocity profiles and initial conditions that correspond to the shear stress \(\tau _s^* = 4.1\tau _{cs}^*\) in a and Fig. 2. c Concentration map of large grains from the advection-diffusion model using constant advection and diffusion coefficients. d Concentration map of large grains from the advection-diffusion model using the experimentally-determined advection profile, but a constant diffusion coefficient with depth. e Temporal evolution of the thickness of the armored layer at shear stress \(\tau _s^* = 4.1\tau _{cs}^*\) calculated from experimental observation corresponding to a and different implementations of the advection-diffusion model
