secondary transition meaning in English

次级转变

While slug structure is leaving from computing domain , the successive disturbance develop in downstream direction , the legs of hair - pin vortex approach the wall continuously and induce vortex structures near the wall . the evolution of this near - wall vortex structures brings the secondary transition to turbulence in the pipe flow
随着塞流结构流出计算域，后继扰动向下游继续发展，表现为发卡涡的涡脚向壁面不断贴近，进而诱发近壁涡结构，近壁涡结构的进一步演化促使圆管流动出现二次转捩，发展到了湍流阶段。
Based on these parameters , the present work studies the transition of pipe flow with the different amplitude of psb disturbance . the present work simulates the whole time - space process of the transition from laminar to turbulence and secondary transition phenomenon in pipe flow for the first time . the main structure in pipe flow transition is hair - pin vortex ; the evolution of hair - pin vortex is related with the transition of pipe flow
在这一组参数下，本文研究了不同扰动幅值的psb扰动作用下圆管流动的转捩过程，首次给出圆管流动从层流转捩到湍流的时空演化全过程，发现了圆管流动的二次转捩现象，并进一步揭示了发卡涡是圆管流动转捩中的主要结构，流动的转捩过程与发卡涡的演化直接相关。