Direct Numerical Simulation of Compressible Multiphase Flows: Shock-Induced Dispersal of Solid and Liquid Material

 

Robert Nourgaliev

Center for Risk Studies and Safety, University of California, Santa Barbara, USA,

robert@engineering.ucsb.edu

 

Understanding the physics of shock waves interacting with clouds of solid particles and liquid droplets is crucial in the development and analysis of several important technological and natural processes. These include explosive dispersal of solid material, shock-induced powder compaction and fluidization, supersonic combustion and explosions, liquid fuel pulse detonation engines, etc. In the past, significant efforts have been invested in the development and application of Direct Numerical Simulation (DNS) methods for incompressible fluid-solid and fluid-fluid (dispersed) flows. In the case of compressible multiphase dispersed systems, to our knowledge, there are no DNS studies available in an open literature.  In the present talk, technical challenges for direct numerical simulation of compressible multiphase flows and shock-induced dispersal of solid and liquid material will be discussed. A new numerical method (named the “Characteristics-Based Matching”, CBM), developed for efficient simulation of complex moving boundaries and interfaces in compressible fluid flows, will be introduced. The CBM is a Cartesian- Grid-based approach, which capitalizes on the latest advancements in the Level-Set/Ghost-Fluid technology and characteristics-based methods for robust and accurate treatment of interfaces. Application of the CBM for DNS of strong shock wave interactions with dense disperse multiphase systems will be demonstrated, including interaction with individual solid particles and liquid droplets, clusters of solid particles and multi-layer solid particle clouds. The particular focus will be placed on importance of proper modeling of particle-particle interactions, including elastic and viscoelastic collisions. Particle-particle collision will be shown to be an important physical mechanism affecting the global dynamics of the dense dispersed multiphase flows.