The present work discusses the impact of the back coupling of the fiber orientation distribution on the base flow and on the fiber orientation itself during mold filling simulations. Flows through a channel and over a backward-facing step are investigated. Different closure approximations are considered for modeling the flow-induced evolution of anisotropy. The results corresponding to the decoupled approach, in which the effect of fibers on local fluid properties is neglected, build the basis of comparison. The modeling is limited to a laminar, incompressible, and isothermal flow of a fiber suspension consisting of rigid short fibers suspended in an isotropic Newtonian matrix fluid. A linear, anisotropic constitutive law is used in combination with a uniform fiber volume fraction of 10% and an aspect ratio of 10. To evaluate the impact of back coupling and of different closure methods in view of the manufactured solid composite the resulting anisotropic elastic properties are investigated based on the Mori–Tanaka method combined with an orientation average scheme. Relative to the range [0, 1] the pointwise difference in fiber orientation between the decoupled and the coupled approach is found to be \(\pm 5{\%}\) in the channel and \(\pm 30{\%}\) in the backward-facing step, respectively. The viscosity and the elasticity tensor show both significant flow-induced anisotropies as well as a strong dependence on closure and coupling.

本工作讨论了在模具填充模拟过程中，纤维取向分布的反向耦合对基流和纤维取向本身的影响。研究了通过通道和朝后步骤的流量。考虑采用不同的闭合近似来模拟流动引起的各向异性演化。对应于解耦方法的结果，其中忽略了纤维对局部流体性能的影响，为比较奠定了基础。建模仅限于由悬浮在各向同性牛顿矩阵流体中的刚性短纤维组成的纤维悬浮液的层流，不可压缩和等温流动。线性各向异性本构定律与均匀的纤维体积分数为10％，纵横比为10结合使用。为了评估背面耦合的影响以及考虑到制成的固体复合材料的不同封闭方法的影响，基于Mori–Tanaka方法与定向平均方案相结合，研究了所得的各向异性弹性性能。相对于[0，1]范围，发现解耦和耦合方法之间的纤维取向逐点差异为频道中的\（\ pm 5 {\％} \）和后向步骤中的\（\ pm 30 {\％} \）。粘度和弹性张量都显示出明显的流动引起的各向异性以及对闭合和耦合的强烈依赖性。