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Memory of shear flow in soft jammed materials
Cessation of flow in simple yield stress fluids results in a complex stress relaxation process that depends on the preceding flow conditions and leads to finite residual stresses. By complementing experiments with numerical simulations we gain new insight into the microscopic origin of these phenomena for jammed suspensions of soft repulsive particles. Our spatio-temporal analysis of microscopic particle motion and local particle configurations highlights that flow in yield stress fluids can be seen as a training process during which the material stores information of the flowing state through the development of domains of correlated particle displacements and the reorganization of particle packings optimized to sustain the flow. This encoded memory can then be retrieved in flow cessation experiments.