DNS Study Of The Interaction Between Turbulence And Particles

Gas-solid multiphase flow has a broad occurrences in the fields of aerospace, shipping, warship, energy, propulsion and chemical industry, etc. Because of the wide gap between the time and spatial scales of the two phases, and the complexity of their movements, the importance of the study on gas-solid multiphase flows is generally acknowledged. Former researches in this field are mainly conducted with the point-particle model, which treats the particle as a mass point, failing to take the volume and surface effect of the particle into account, and to explain some phenomenon observed in gas-solid turbulence.The present research facilitates a fully resolved method to study the interaction between fully resolved particles and turbulence. At first, an isotropic turbulent box is modified into a non-periodical domain, and a single particle immersed in the turbulence of infinite length is simulated. The results is compared with literature and well validated, to show the accuracy of the present method in a turbulent environment. To study the influence of the relative position of the particles on each other, simulations are conducted with two aligned spherical particles moving in the turbulence under different turbulent intensities and particle Reynolds numbers. The modulation of the turbulence by the particles is studied and the influence of the particle distances on the forces endured by the particles are discussed. The movements of fully resolved particles in a zero pressure gradient spatially developing turbulent boundary layer is also studied. A soft sphere collision model for immersed boundary method is developed to replace the repulsion model, and a turbulent boundary layer database is used for the establishment of a single phase flow field and the particle laden one. This is the first-ever turbulent boundary layer laden with fully resolved particles and the results compared between the two fields are of important value.