The lift force acting on a purely translational galloping oscillator can be well approximated by using the quasi-steady theory, which states that the flow around a galloping body in motion is very similar to the known flow around a fixed body provided a minimum free stream velocity threshold and a similarity principle are satisfied. However, for oscillators undergoing coupled translational–rotational galloping, the rotation of the bluff body breaks the similarity principle, and therewith the quasi-steady assumption. Traditionally, the effects of rotation are accounted for by including explicit time-dependent terms in the lift force. However, we argue that the time-explicit representation of the lift force is unnecessary because the phenomenon of galloping is not time-explicit and acts only as a function of the body motion. Thus, we propose a modified time-implicit lift force representation, which has the same form of the quasi-steady theory, but with an additional dependence on the free stream velocity. The modified lift force is obtained by studying the transient growth of the amplitude of the bluff body oscillation. The proposed approach is used to model the lift force for square and trapezoidal prisms undergoing coupled translational–rotational galloping showing excellent prediction capabilities.

可以使用准稳态理论很好地估算作用在纯平移式振子振荡器上的升力，该理论认为，在最小自由流速度的情况下，运动中的振子周围的流与已知的固定体周围的流非常相似。满足阈值和相似性原则。但是，对于经历平移-旋转耦合舞动的振荡器，钝体的旋转破坏了相似原理，并由此推定了准稳态假设。传统上，旋转的影响是通过在举升力中包括明确的时间相关项来解决的。但是，我们认为，没有必要用时间来表示提升力，因为舞动现象不是时间上的而是仅是身体运动的函数。因此，我们提出了一种修正的时间隐式提升力表示，其具有与准稳态理论相同的形式，但还对自由流速度有额外的依赖性。通过研究钝体振动幅度的瞬时增长，可以得到修正的升力。所提出的方法用于对经受出色的预测能力的平移-旋转驰gall耦合的方形和梯形棱镜的升力进行建模。