SI2-SSE: A Next-Generation Open-Source Computational Fluid Dynamic Code for Polydisperse Multiphase Flows in Science and Engineering

用于生产药物、燃料和塑料材料以及来自煤或生物质的能量的许多过程涉及多相流，多相流由流体（液体或气体）和颗粒、液滴或气泡的组合组成。这种流动也自然存在于环境中。例如，火山爆发形成的空气和固体颗粒的混合物，以及风携带的沙子和其他物质的颗粒。科学家和工程师使用软件来研究这些流动的行为，以提高工业过程的产量，减少其对环境的影响和能源消耗。用于执行这些研究的计算机程序解决复杂的数学问题，并且需要强大的计算机能够在有用的时间内获得结果。该项目的重点是开发下一代多相流模拟计算机软件，使其能够使用最新一代计算机，其中结合了联合收割机传统和图形处理器，以提高性能。该软件将向公众发布，并将使来自不同研究领域的科学家和工程师能够利用多相流科学的最新发展来解决现实世界的问题，并能够在强大的计算机基础设施上使用该软件。学生和教育工作者将能够使用该软件，并通过将提供的示例和文档了解多相流。该项目的目标将通过首先开发计算模型来实现，以在基于正交的矩量方法的框架内描述湍流，这是一种有效和准确的方法来描述这种类型的流动。然后，这些计算模型将与适当的数值方法一起在开源框架OpenFOAM中实施，以确保计算代码的准确性。三个典型的多相流的代表性问题将被考虑：一个人口平衡方程的粒子与可忽略的惯性，如在流体流中的纳米粒子的形成;气液流动的描述，其中气泡的惯性是小的，但不为零;和最复杂的情况下的气固流动，其中颗粒的惯性是大的。OpenFOAM框架将增加使用图形处理单元的可能性，使其能够在涉及传统处理器和图形处理单元的混合计算系统上运行。源代码及其文档将在其开发的早期阶段根据GNU GPL 3许可证向公众提供，以传播研究结果并收集反馈。还将创建详细的代码文档、验证和确认案例以及教程，以支持对软件的外部贡献。

Many processes for the production of drugs, fuels and plastic materials, as well as energy from coal or biomasses, involve multiphase flows, which are composed by a combination of a fluid, either liquid or gas, and particles, droplets or bubbles. This type of flow is also naturally present in the environment. Examples are the formation of a mixture of air and solid particles due to volcanic eruptions, and particles of sand and other materials transported by the wind. Scientists and engineers use software to study how these flows behave in order to improve the yield of industrial processes, reduce their environmental impact, and energy consumption. The computer programs used to perform these studies solve complex mathematical problems, and require powerful computers to be able to obtain the results in a useful time. This project focuses on developing the next generation of computer software for the simulation of multiphase flows, enabling it to use the latest generation of computers which combine traditional and graphical processors for improved performance. This software will be released to the public and will enable, scientists and engineers from different research areas to tackle real-world problems by taking advantage of the latest developments in multiphase flow science, combined with the benefit of being able to use the software on powerful computer infrastructures. Students and educators will be able to use the software and learn about multiphase flows through the examples and the documentation that will be provided.The objectives of the project will be achieved by first developing computational models to describe turbulent flows in the framework of quadrature-based moment methods, an efficient and accurate approach to describe this type of flows. These computational models will then be implemented, together with appropriate numerical methods that will ensure the accuracy of the computational codes, in the open-source framework OpenFOAM. Three representative problems of typical multiphase flows will be considered: a population balance equation for particles with negligible inertia, such as in the formation of nanoparticles in a fluid flow; the description of gas-liquid flows, where the bubble inertia is small but not zero; and the most complex case of gas-solid flows, where particle inertia is large. The possibility of using graphical processing units will be added to the OpenFOAM framework, to enable it to run on hybrid computational systems involving traditional processors and graphical processing units. The source code and its documentation will be made available to the public at an early stage of their development, under the GNU GPL 3 license, in order to disseminate the results of the research and gather feedback. Detailed code documentation, verification and validation cases, and tutorials will also be created to favor external contributions to the software.