Mischungsvorgänge im Meerwasser durch aktive Schwimmer
Zusammenfassung der Projektergebnisse
This project focused on the Direct Numerical Simulation (DNS) of mass-transfer in particle-laden flows with scopes in Geophysics, Chemical Engineering, and pure Fluid Mechanics. The scholar deviated from the originally proposed plan because of newly appeared publications and a Ph.D. student at the local host institution, who successfully worked on parts of the originally proposed research plan. We developed and implemented numerical methods to simulate mass-transfer that extended the local in-house-particle-fluid flow solver. We found that for the direct numerical simulations of particle-laden flows, where the motion of particles is treated via an Immersed-Boundary Method on a regular Cartesian mesh, an efficient scheme to represent the impermeability of particles is via a discontinuous diffusion coefficient and its discretization using a Volume of Fluid type scheme. Using this flow solver and granted computation time by the XSEDE program several projects were initiated. The main research project pursued was in collaborations with the group of Prof. R. Nokes (University of Canterbury, New Zealand), especially a PhD-student, A. Meredith. We investigated the interaction of saline gravity currents that spread over a bottom that is made of layers of mono-disperse spheres in a combined experimental-numerical approach. This was interesting because we were able, in terms of capabilities of PARTIES and the granted computing times from the XSEDE program, to represent the experimental geometry on a one-to-one scale and to making only a few trade-offs in the modeling of their experimental setup. The results were described in a draft that was submitted for publication in the Journal of Fluid Mechanics. More projects were initiated but no coherent results for publication could be achieved in the funding period. Our efforts included the simulations of erosion by saline gravity currents, buoyancy-driven flows inside porous media and the development of fingering patterns during the flow of dense suspension through a narrow channel. Unfortunately, the scientific output of the project was just one submitted paper covering the gravity current simulations. The method development was novel but was described in a publication by another group at the time, we finished the implementation and validation. Substantial simulations on the erosion of particle beds by saline gravity currents were performed including different setups, but though substantial computing time was granted and broad scientific interest, we could not finish a publishable study due to the exceptional numerical efforts required to study a meaningful setup.
