Multiphase flows are commonly found in chemical engineering processes such as distillation columns, bubble columns, fluidized beds and heat exchangers. Physical boundaries in numerical simulations of multiphase flows are generally defined by a mesh that conforms to the physical boundaries of the system. Depending on the complexity of the physical system, generating the conformal mesh can be time-consuming and the resulting mesh could potentially contain a large number of skewed elements, which is undesirable. The diffuse-interface approach allows for a structured mesh to be used while still capturing the desired solid-fluid boundaries. In this work, a diffuse-interface method for the imposition of physical boundaries is developed for two-fluid incompressible flow systems. The diffuse-interface is used to define the physical boundaries and the boundary conditions are imposed by blending the conservation equations from the two-fluid model with that of the solid. The results from the diffuse-interface method and mesh-defined boundaries are found to be in good agreement at small diffuse-interface widths.

中文翻译：

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扩散界面混合法在双流体流中施加物理边界

多相流通常在化学工程过程中发现，例如蒸馏塔，鼓泡塔，流化床和热交换器。多相流数值模拟中的物理边界通常由符合系统物理边界的网格定义。取决于物理系统的复杂性，生成共形网格可能很耗时，并且生成的网格可能包含大量的倾斜元素，这是不希望的。扩散界面方法允许使用结构化的网格，同时仍然捕获所需的固体-流体边界。在这项工作中，为两种流体不可压缩的流动系统开发了一种施加物理边界的扩散界面方法。扩散界面用于定义物理边界，边界条件是通过将双流体模型的守恒方程与固体方程混合而成的。发现在较小的扩散界面宽度下，扩散界面方法和网格定义的边界的结果具有良好的一致性。