CFD Simulation of Wall-Bounded Laminar Flow Through Screens: Part II — Mixing Characterization

This paper characterizes the mixing behavior of laminar flows within a circular pipe equipped with plain woven meshes or screens, acting as static mixers. In this quest, their performance was numerically investigated using the Lagrangian particle method in a commercial CFD solver, whereby the effect of changing the screen geometry, number of screens, inter-screen spacing, and operating conditions were considered. Mixing was addressed from a distributive and dispersive perspectives using both qualitative and quantitative descriptions. The distributive mixing indicated that a central injection of a single fluid should be coupled with a short inter-screen spacing to better spread the particles and enhance mixing as opposed to a larger inter-screen spacing. On the contrary, the mixing of two immiscible fluids of similar properties reveal that a large inter-screen spacing is recommended. From a dispersive mixing perspective, extensional efficiency contours revealed that the fluid would undergo all three modes of flow behavior, each of which dominating a certain region depending on the location with respect to the screen. Finally, it was interesting to find that a coarser screen geometry consistently outperformed finer screens in spreading and mixing the particles.

Tsunami simulation using particle method

Tsunami is a natural disaster that have resulted in dreadful damages over time. Extensive researches have been conducted to scrutinize and counteract the natural hazard using three major research components which are: field monitoring, laboratory tests, and numerical methods. However, laboratory tests are high-priced and arduous. Numerical simulation overcomes these drawbacks and can be utilized in collaboration with laboratory tests. Recently, newly introduced meshless Lagrangian particle method called Smoothed Particle Hydrodynamics (SPH) has gained attention. In this paper, SPH method has been employed to simulate tsunami. A SPH code is developed from scratch. To validate the code, a traditional dam break simulation is conducted. Lastly, a tsunami model is simulated using the developed SPH code and compared with past experimental data. The results indicate that the code is in accordance with previous experimental data and numerical simulation. Whereby, there’s been a slight deviation arises in tsunami simulation. The velocity of the code is relatively less to that of the experimental data. Such inconsistencies could emerge due to a number of reasons, i.e. the choice of the SPH parameters and model simplification. Generally, the developed SPH code had a satisfactory performance to model tsunami and dam-break problem.