Accurate numerical simulation of material extrusion additive manufacturing requires reliable tracking of evolving material interfaces while preserving mass conservation. Inaccurate mass conservation can lead to significant discrepancies between simulated and deposited strand geometries, undermining the predictive capability of the model. In this work, we investigate the mass conservation performance of the conservative level-set (CLS) method in extrusion-based 3D printing simulations. A systematic parametric study is conducted to quantify the influence of the interface thickness and reinitialization parameters on mass conservation, using the steady-state cross-sectional area of deposited strands as a quantitative metric. Simulated cross-sections are compared against reference values obtained from analytical mass balance relations. The results show that reducing both the interface thickness and the reinitialization parameter improves mass conservation accuracy, although diminishing returns and increased computational cost are observed beyond certain thresholds. In addition, appropriate tuning of the interface thickness can relax mesh refinement requirements while maintaining acceptable accuracy. The proposed parameter selection strategy is validated across a range of printing conditions, materials, and nozzle geometries, including multilayer deposition of viscoplastic fluids. The simulations show reasonable agreement with experimentally validated data from the literature, confirming that careful CLS parameter tuning enables accurate and computationally efficient prediction of strand geometry in extrusion-based 3D printing.

翻译：材料挤出增材制造的精确数值模拟需要在保持质量守恒的同时可靠追踪演化的材料界面。不准确的质量守恒会导致模拟的沉积丝状体几何形状与实际沉积结果产生显著差异，从而削弱模型的预测能力。本研究探讨了保守水平集（CLS）方法在挤出式3D打印模拟中的质量守恒性能。通过系统性的参数研究，以沉积丝状体稳态横截面积为量化指标，分析了界面厚度与重新初始化参数对质量守恒的影响。模拟获得的横截面结果与基于解析质量平衡关系得到的参考值进行比较。结果表明，减小界面厚度和重新初始化参数均可提升质量守恒精度，但超过特定阈值后会出现收益递减且计算成本显著增加的现象。此外，适当调整界面厚度可在保持可接受精度的同时降低网格细化要求。所提出的参数选择策略在一系列打印条件、材料及喷嘴几何构型（包括黏塑性流体的多层沉积）中得到了验证。模拟结果与文献中经实验验证的数据具有合理的一致性，证实通过精细调整CLS参数能够实现挤出式3D打印中丝状体几何形状的精确且计算高效的预测。