| 研究実績の概要 |
The first aim of this research was to further enhance a previously proposed Lagrangian multiphase computational code for a more proper and physical modeling of entrapped air dynamics in water slamming problems. In this regards, specifically, interface stability in presence of large density ratio is a crucial issue. To find a solution for this challenging numerical issue, a new scheme, namely, OPS (Optimized Particle Shifting) was proposed and was just published in Journal of Computational Physics. The newly proposed OPS scheme is shown to drastically improve the stability and accuracy by minimizing unphysical particle perturbations without adversely affecting the reproduced physics. This scheme is shown to be superior to several other stabilizing schemes (such as Particle Shifting, First-order accurate Density Smoothing, Dynamic Stabilization, etc.). The OPS has also been implemented in our multiphase codes and its enhancing effects have been clearly shown and validated. A paper on this matter is accepted and will be presented in a forthcoming international workshop, namely, 12th International SPHERIC workshop that will be held in Ourense, Spain in June 2017.
In addition, in a separate journal paper published in European Journal of Mechanics B/Fluids, we have done a detailed study on implementation of the most proper pressure gradient model for accurate particle-based simulations with consideration of most accurate reproduction of actual physics. Hence, the most proper scheme will be adopted for the target of this study.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
2: おおむね順調に進展している
理由
The anticipated aim for 2016, namely, stabilization and enhancement of the previously proposed Lagrangian multiphase computational code has already been achieved by implementing a newly proposed OPS scheme and proper implementation of a consistent pressure gradient model. More validations are currently being conducted and the developed code will be soon coupled with a non-linear elastic structure model (that is being developed in parallel and partly published in Journal of JSCE, Coastal Eng). For this reason, the progress can be considered to be rather smooth.
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| 今後の研究の推進方策 |
For the time being, one of the major challenge in simulation of multiphase flows characterized by large density ratios corresponds to presence of unphysical perturbations at the phase interface. For an accurate and reliable modeling, it is important to have precise implementation of interface boundary conditions and model the corresponding physics as accurate as possible. The OPS scheme together with the validated consistent pressure gradient model are shown to resolve this issue to a great extent. The next step corresponds to coupling of the so-far developed enhanced multiphase flow model with a non-linear elastic structure model to take into account the hydroelasticity effects for a more reliable and accurate reproduction of water slamming problems encountered in ocean engineering. This aim is expected to be achieved in 2017. The structural model is separately developed, needs to be further validated and then being coupled with the enhanced multiphase flow model in a mathematically sound and physically consistent manner.
It should be mentioned here that in order to disseminate latest achievements and have comments of respected experts a workshop on particle methods will be organized by the researcher during May 9-11 at Kyoto University, Katsura campus.
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