斑马鱼C型起动不仅发生于逃逸响应（C型逃逸），而且发生于非逃逸响应（C型转弯）。它们具有不同的变形模式和周期，并且运动学性能各异。在相同的弯曲幅度下，C型转弯实现更大的转弯角度，而C型逃逸则具有更快的游动速度。但尚不清楚它们的水动力学机制和力能学特征。本文针对C型转弯和逃逸的变形特征，建立新的曲率模型，采用优化算法拟合模型参数。通过自主游动数值模拟，发现C型转弯实现大转弯的机制在于：弯曲阶段存在比较大的正向力矩，而回摆阶段存在比较小的反向力矩；而C型逃逸在回摆阶段存在比较大的推力，导致反向力矩增大和转弯角度变小。还发现周期对转弯角度的影响不大，但对逃逸速度和能量消耗影响显著。因此，C型转弯为了节省能量，周期通常在100 ms以上；而C型逃逸为了追求高速度，周期则在50 ms附近。
The zebrafish C-start occurs not only in the escape response (C-escape), but also in the non-escape response (C-turn). They have different deforming modes and durations, and put in distinct kinematics performances. With the same bending amplitude, C-turns achieve larger turning angles, while C-escapes have higher velocities. However, little is known about their hydrodynamic mechanisms and energetics features. We proposed two novel curvature models based on the deformation characteristics of C-turn and C-escape, respectively. An optimization algorithm was used to determine the model parameters according to experimental data. Through self-propelled numerical simulation, we found that the positive moment at stage 1 of C-turn was large and the negative moment at stage 2 was small. So C-turn achieved a large turning angle. However, C-escape had a large thrust at stage 2, which led to the negative moment increasing and the turning angle reducing. We also found that the duration had little effect on the turning angle, but had a significant influence on escape velocity and energy consumption. Therefore, in order to save energy the duration of C-turn is usually over 100 ms, and the duration of C-escape is near 50 ms in order to pursue high speed.
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