Dr. Manuel Falcone
Development and Application of a Direct Numerical Method for Reactive Transport Processes in Bubble Systems
Various industrial applications based on two-fluid systems require a detailed knowledge of the two-phase flow hydrodynamics as well as of the interfacial mass transfer. An understanding of these phenomena can be obtained either experimentally or by means of simulation methods. Even though in the last years new experimental techniques have been developed to investigate mass transfer across interfaces, most of them provide only integral information and cannot provide a detailed insight into these physical processes. Accordingly, it has emerged more and more the need of developing sophisticated numerical methods able to capture the physical information that is not possible to obtain by means of the experimental activities.
This project is concerned with both the development and application of a Direct Numerical Method for reactive mass transfer at dynamic interfaces in multiple bubble systems. Two crucial properties for a high-fidelity Direct Numerical Method for reactive mass transfer, namely adaptive and sufficient spatial resolution and intrinsic conservation, are conceptually combined to the proposed hybrid (Lagrangian/Eulerian) method. The Lagrangian part is intended to fully resolve the sharp concentration gradients occurring for realistic Péclet and Hatta numbers, while the method's overall conservative property results from the Eulerian one.
By applying the method, it is investigated (i) the complex interplay at the bubble interface between two-phase hydrodynamics, local transport processes, and chemical reactions, and (ii) the quantitative relative importance of above phenomena near the bubble interface on the degree of liquid phase utilization, product selectivity and byproduct formation for competitive prototype reactions within the bubble wake.
The development and the application of the novel method is done within the framework of the free open source C++ library OpenFOAM for Computational Continuum Mechanics.
The author thanks the German Research Foundation (DFG) for financial support within the Priority Program SPP 1740 “Influence of Local Transport Processes on Chemical Reactions in Bubbly Flows”.
 J. G. Khinast, A. A. Koynov, and T. M. Leib. Reactive mass transfer at gas-liquid interfaces: micro-scale fluid dynamics on yield and selectivity of liquid-phase cyclohexane oxidation. Chemical Engineering Science, 58(17): 3961-3971, 2003.
 B. Šarler, and R. Vertnik. Meshfree explicit local radial basis function collocation method for diffusion problems. Computer & Mathematics with applications, 51(8): 1269-1282, 2006.
 D. Stevens, H. Power, M. Lees, and H. Morvan. The use of PDE centres in the local RBF Hermitian method for 3D convective-diffusion problems. Journal of Computational Physics, 228(12): 4606-4624, 2009.
 S. Reboux, B. Schrader, and I. F. Sbalzarini. A self-organizing Lagrangian particle method for adaptive-resolution advection-diffusion simulations. Journal of Computational Physics, 231(9): 3623-3646, 2012.
 O. Awile, F. Büyükkeçeci, S. Reboux, and I. F. Sbalzarini. Fast neighbor lists for adaptive-resolution particle simulations. Computer Physics Communications, 183(5): 1073-1081, 2012.