Coupling between countercurrent gas and solid flows in a moving granular bed: The role of shear bands at the walls

► We theoretically study gas maldistribution in countercurrent gas-solid flow in ducts. ► We couple the gas flow and the continuum rheology of the granular solids. ► Friction-induced dilation of the solids induces preferential paths of the gas. ► Charts are given for the dependence of maldistribution on gas and solid flowrates. ► The effect of system parameters on the gas residence time distribution is studied.