The dynamics of streaky structures in a viscoelastic pipe flow of FENE-P fluids is studied numerically. The values of Weissenberg number ($Wi$, polymer relaxation time over flow turn-over time) and viscosity ratios are varied to evaluate the effects of viscoelasticity in the pipe. For Reynolds numbers $3000\sim 3500$ (based on pipe radius and maximum laminar velocity) near the transition boundary, we select finite-amplitude two-dimensional rolls as initial conditions and add infinitesimal three-dimensional perturbations to trigger the transition. The 2D streamwise rolls are highly unstable to small 3D disturbances, which helps to better understand the evolution of large scale structures. The stronger temporal intermittency in viscoelastic flows makes it more difficult to identify a successful transition; we found that quantities directly related to viscoelasticity can serve as better indicators of transition to turbulence. The role of polymer stress is studied through the kinetic energy budget and it is found that polymer torque opposes the vorticity and become more dominant for higher $Wi$, consistent with previous studies. The results show that the secondary instability of the streaky structures can be enhanced by viscoelasticity at low $Wi$, while at high $Wi$ viscoelasticity delays the transition to turbulence, sometimes leading to relaminarization.

对 FENE-P 流体粘弹性管流中条纹结构的动力学进行了数值研究。Weissenberg 数的值 ($宽\mathrm{一世}$，聚合物松弛时间与流动周转时间）和粘度比变化以评估管道中粘弹性的影响。对于雷诺数$3000～3500$（基于管道半径和最大层流速度）在过渡边界附近，我们选择有限幅度的二维滚动作为初始条件，并添加无穷小的三维扰动来触发过渡。2D 流向滚动对小的 3D 扰动高度不稳定，这有助于更好地理解大尺度结构的演化。粘弹性流动中更强的时间间歇性使得识别成功的转变变得更加困难；我们发现与粘弹性直接相关的数量可以作为向湍流过渡的更好指标。通过动能预算研究了聚合物应力的作用，发现聚合物扭矩与涡量相反，并且在更高的条件下变得更占优势。$宽\mathrm{一世}$，与以往的研究一致。结果表明，低粘弹性可以增强条纹结构的二次不稳定性。$宽\mathrm{一世}$, 而在高 $宽\mathrm{一世}$ 粘弹性延迟了向湍流的过渡，有时会导致再分层。