We present a semi-coupled resolved Computational Fluid Dynamics (CFD) and Discrete Element Method (DEM) to simulate a class of granular media problems that involve thermal-induced phase changes and particle–fluid interactions. We employ an immersed boundary (IB) method to model the viscous fluids surrounding solid particles in conjunction with a fictious CFD domain occupied by the actual positions of the particle. Heat transfers between the actual fluids and the fictitious particle are treated as a multiphase problem by the CFD to resolve the temperature gradient distribution within each granular particle and its possible phase change (e.g., melting or partial melting). The mechanical interactions between the solid particles and the fluids are modeled by coupled DEM and CFD. The proposed method is validated by simulations of a typical powder-based selective laser melting (PB-SLM) process. Three key SLM input parameters, laser power, laser energy distribution and hatch distance, are examined on the effect of melting. The simulation results capture key features and observations of PB-SLM found in experiments and are quantitatively consistent with available testing data. The study provides a physically based, high-fidelity computational approach for future PB-SLM additive manufacturing.

我们提出了一种半耦合的解析计算流体动力学（CFD）和离散元方法（DEM），以模拟涉及热致相变和颗粒-流体相互作用的一类颗粒介质问题。我们采用沉浸边界（IB）方法对固体颗粒周围的粘性流体以及虚拟CFD域进行建模，该CFD域被颗粒的实际位置占据。CFD将实际流体与虚拟颗粒之间的传热视为多相问题，以解决每个颗粒内的温度梯度分布及其可能的相变（例如熔融或部分熔融）。固体颗粒和流体之间的机械相互作用通过耦合DEM和CFD建模。通过对典型的基于粉末的选择性激光熔化（PB-SLM）工艺的仿真，验证了所提出的方法。三键检查SLM输入参数，激光功率，激光能量分布和孵化距离对熔化的影响。仿真结果捕获了实验中发现的PB-SLM的关键特征和观察结果，并且与可用的测试数据在数量上是一致的。该研究为未来的PB-SLM增材制造提供了一种基于物理的高保真计算方法。