Liquid composite molding (LCM) simulations for processes such as resin transfer molding (RTM) and vacuum assisted resin transfer molding (VARTM) face serious challenges while modelling resin flow through dual scale fabrics such as bi-directional (BD) (stitched or woven) fabrics and triaxial fabrics as it requires characterization of two permeability values: inter-tow gap or bulk permeability and tow permeability. Conventional experimental methodologies can characterize the inter-tow gap permeability by tracking the wetting resin flow front; however, there is no closed form solution that gives an expression for effective wetting permeability due to the uncertainty in determining tow permeability explicitly. If one were to have prior knowledge of tow permeability, effective wetting permeability can be formulated that can reduce the effort of experimental characterization. The current study proposes closed form permeability model for dual scale unidirectional (UD) fabric that combines both the tow and inter-tow gap permeability while taking into account the effect of partially saturated zone during dual scale flow. Thus, it accounts for the effects of inter-tow gap permeability, tow permeability and length of partially saturated zone. Comparisons of the analytic model results with numerical simulations are presented that are encouraging.

树脂传递模塑 (RTM) 和真空辅助树脂传递模塑 (VARTM) 等工艺的液体复合成型 (LCM) 模拟在模拟树脂流经双向 (BD)（缝合或编织）等双尺度织物时面临严峻挑战织物和三轴织物，因为它需要表征两个渗透率值：丝束间间隙或体积渗透率和丝束渗透率。传统的实验方法可以通过跟踪润湿树脂流动前沿来表征丝束间隙渗透率；然而，由于明确确定丝束渗透率的不确定性，没有封闭形式的解决方案给出有效润湿渗透率的表达式。如果人们对丝束渗透性有先验知识，可以制定有效的润湿渗透率，从而减少实验表征的工作量。目前的研究提出了双尺度单向 (UD) 织物的封闭形式渗透率模型，该模型结合了丝束和丝束间隙渗透率，同时考虑了双尺度流动过程中部分饱和区的影响。因此，它考虑了丝束间隙渗透率、丝束渗透率和部分饱和带长度的影响。分析模型结果与数值模拟的比较令人鼓舞。它考虑了丝束间隙渗透率、丝束渗透率和部分饱和带长度的影响。分析模型结果与数值模拟的比较令人鼓舞。它考虑了丝束间隙渗透率、丝束渗透率和部分饱和带长度的影响。分析模型结果与数值模拟的比较令人鼓舞。