Finite-size particles in homogeneous turbulence: a numerical study

• Applicant: Professor Dr. Markus Uhlmann
• Subject Area: Fluid Mechanics
• Term: from 2010 to 2015
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 183403163

We propose to study via direct numerical simulation (DNS) the basic mechanisms involved in the interaction between a dilute dispersed phase (consisting of solid particles) and a homogeneous turbulent (or self-induced) flow subjected to a gravitational field. The two-phase flow regime under consideration can be characterized by particle Reynolds numbers of O(100) and particle diameters comparable to or larger than the smallest flow scales. Therefore, the common point-particle approximation is not directly applicable. As a consequence, we fully resolve the phase interfaces as well as all relevant flow scales. The proposed flow configuration is statistically homogeneous, consisting either of an initially isotropic turbulent field or of ambient fluid to which heavy particles are added. This situation is an idealization of flow conditions encountered e.g. in the atmosphere (clouds) or in chemical engineering processes. The analysis of the data generated in this project (flow field and particle motion) will be guided by the following fundamental questions: How is the settling velocity in turbulent background flow affected by finite-size, finite-Reynolds-number and collective effects? What are the mechanisms of particle-induced turbulence enhancement/attenuation? How is the spatial distribution of the disperse phase influenced by the problem parameters? How do heavy particles modify existing flow structures/generate new structures? It can be expected that the results of the proposed research will further promote our understanding of particulate flow dynamics. Moreover, the insight gained will benefit future efforts to improve existing engineering-purpose models of such flows.

• DFG Programme: Research Grants
• International Connection: France, USA
• Participating Persons: Professor Sivaramakrishnan Balachandar, Ph.D.; Professor Dr. Mickael Bourgoin; Professor Dr. Jan Dusek