The dynamics of an elastic fiber with various initial states in a laminar channel flow is investigated using the immersed boundary-lattice Boltzmann method. Fiber-wall collisions are solved by adding a repulsive force in the model. Our simulation results demonstrate that the initial fiber state closely relates to the stability of the considered conveyance system. Different initial states may lead to different dynamic patterns in the downstream. The fiber is found to go straight forward along a horizontal path when it is horizontally and symmetrically placed at the channel centerline. Breaking this symmetry by varying the fiber's initial vertical position or orientation will induce the instability of the system, which then causes deviations and fluctuations in fiber's conveyance path. No matter how large the deviation occurs in the upstream, the fiber is always found to migrate to the channel central region in the downstream and would eventually settle in a vertical position slightly away from the channel centerline. Moreover, the off-centerline distance that a fiber settles depends on its dynamic pattern rather than a specific initial fiber state. For our system, there are two kinds of dynamic patterns observed in the downstream channel. In the first pattern, the fiber eventually reaches its equilibrium state and is observed to do a translational motion. In the second pattern, no equilibrium state is observable, and the fiber is found to do a periodically tumbling motion. The fiber's eventual conveyance speed depends on the vertical position it eventually settles and can be roughly approximated by the local flow velocity.

使用浸没边界格子Boltzmann方法研究了层流通道流动中具有各种初始状态的弹性纤维的动力学。通过在模型中添加排斥力可以解决纤维壁碰撞。我们的仿真结果表明，初始纤维状态与所考虑的输送系统的稳定性密切相关。不同的初始状态可能导致下游的动态模式不同。当将光纤水平对称地放置在通道中心线时，它会沿着水平路径笔直向前移动。通过改变光纤的初始垂直位置或方向来打破这种对称性会导致系统不稳定，从而导致光纤传输路径出现偏差和波动。不管上游有多大的偏差，总是发现光纤向下游的通道中心区域迁移，并最终定居在稍微远离通道中心线的垂直位置。此外，纤维沉降的偏离中心线的距离取决于其动态模式，而不是特定的初始纤维状态。对于我们的系统，在下游通道中观察到两种动态模式。在第一种模式中，纤维最终达到其平衡状态，并被观察到发生平移运动。在第二种模式中，没有观察到平衡状态，并且发现纤维周期性地滚动。纤维的最终传输速度取决于最终沉降的垂直位置，并且可以通过局部流速粗略估算。