Coherent Structures and Extreme Events in Rotating Multiphase Turbulent Flows
نویسندگان
چکیده
By using direct numerical simulations (DNS) at unprecedented resolution, we study turbulence under rotation in the presence of simultaneous direct and inverse cascades. The accumulation of energy at large scale leads to the formation of vertical coherent regions with high vorticity oriented along the rotation axis. By seeding the flowwithmillions of inertial particles,wequantify—for the first time—the effects of those coherent vertical structures on the preferential concentration of light and heavy particles. Furthermore, we quantitatively show that extreme fluctuations, leading to deviations from a normal-distributed statistics, result from the entangled interaction of the vertical structures with the turbulent background. Finally, we present the first-ever measurement of the relative importance between Stokes drag, Coriolis force, and centripetal force along the trajectories of inertial particles. We discover that vortical coherent structures lead to unexpected diffusion properties for heavy and light particles in the directions parallel and perpendicular to the rotation axis.
منابع مشابه
On Coherent Structures of Turbulent Open-channel Flow Above a Rough Bed
Present study examines turbulent structures of a rough bed open-channel flow in the context of deterministic approach. Instantaneous velocity field is measured in different hydraulic conditions using two dimensional Particle Image Velocimetry (PIV) in vertical plane and Stereoscopic PIV in horizontal plane. Different techniques and quantities such as swirl strength, two-point and cross-correlat...
متن کاملOverview of Direct Numerical Simulation of Particle Entrainment in Turbulent Flows
An overview of removal and re-entrainment of particles in turbulent flows is presented. The procedure for the direct numerical simulation (DNS) of the Navier-Stokes equation via a pseudospectral method for simulating the instantaneous fluid velocity field is described. Particle removal mechanisms in turbulent flows in a duct are examined and effects of the near-wall coherent eddies on the parti...
متن کاملPhysical theory for near-bed turbulent particle-suspension capacity
The inability to capture the physics of solid-particle suspension in turbulent fluid flow is holding back application of multiphase computational fluid dynamics techniques to the many problems involving particle suspension in nature and society. We present a theory for particle suspension capacity near no-slip frictional boundaries of turbulent flows. The suspension capacity parameter Γ include...
متن کاملIdentification and synoptic analysis of the highest precipitation linked to ARs in Iran
Atmospheric rivers (ARs) are long-narrow, concentrated structures of water vapour flux associated with extreme rainfall and floods. Accordingly, the arid and semi-arid regions are more vulnerable to this phenomenon. Therefore, this study identifies and introduces the highest precipitation occurred during the presence of ARs from November to April (2007-2018). The study also attempted to...
متن کاملExact Coherent Structures in Turbulent Shear Flows
Exact coherent structures are three-dimensional, nonlinear traveling wave solutions of the Navier-Stokes equations. These solutions are typically unstable from onset, yet they capture the basic statistical and structural features of low Reynolds number turbulent shear flows remarkably well. These exact coherent structures have now been found in all canonical shear flows: plane Couette, Poiseuil...
متن کامل