2016/02/16 by Marco Dentz, Dentz, Marco, Daniel Lester +5
Chemical Engineering · Engineering · #60G51 #76S05 #FOS: Physical sciences #Fluid Dynamics (physics.flu-dyn) #Fluid Dynamics and Turbulent Flows #Lattice Boltzmann Simulation Studies #Rheology and Fluid Dynamics Studies
paper · pdf · doi:10.48550/arxiv.1602.04904
openalex publication_date 2016/02/16 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We study the relation between flow structure and fluid deformation in steady two-dimensional random flows. Beyond the linear (shear flow) and exponential (chaotic flow) elongation paradigms, we find a broad spectrum of stretching behaviors, ranging from sub- to superlinear, which are dominated by intermittent shear events. We analyze these behaviors from first principles, which uncovers stretching as a result of the non-linear coupling between Lagrangian shear deformation and velocity fluctuations along streamlines. We derive explicit expressions for Lagrangian deformation and demonstrate that stretching obeys a coupled continous time random walk, which for broad distributions of flow velocities describes a Lévy walk for elongation. The derived model provides a direct link between the flow and deformation statistics, and a natural way to quantify the impact of intermittent shear events on the stretching behavior, which can have strong anomalous diffusive character.