Abstract In this paper we present a computational model to simulate surface waves on photo-responsive liquid crystal thin films under dynamic illumination. The influence of light attenuation is included to model the dynamic photo-mechanical response as a result of the forward (trans to cis) and the backward (cis to trans) isomerization of the embedded azobenzene molecules. The viscoelastic nature of the liquid crystal films is also estimated and incorporated in this study. The temporal response of the material under static spot illumination is analyzed first to understand the underlying mechanisms behind the observed response. The relation between the fraction of transformed molecules and the macroscopic light induced strains and stresses through the thickness is investigated to establish the significance of light attenuation. Subsequently, the model liquid crystal film is exposed to a rectangular illumination waveform to simulate a moving light source and thereby generate surface waves. Results are presented that relate the wave attributes, (i.e., the amplitude, frequency and phase lag) to the time scales associated with the moving light source, the molecular trans-cis isomerization reaction and the viscoelastic response of the material. A design guideline for producing surface waves with specific features (amplitude, phase) is presented.

中文翻译：

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移动光源下光响应粘弹性液晶薄膜表面波的建模

摘要 在本文中，我们提出了一个计算模型来模拟动态照明下光响应液晶薄膜上的表面波。包括光衰减的影响以模拟由于嵌入的偶氮苯分子的正向（反式到顺式）和反向（顺式到反式）异构化而导致的动态光机械响应。液晶薄膜的粘弹性性质也被估计并纳入本研究。首先分析静态点照明下材料的时间响应，以了解观察到的响应背后的潜在机制。研究转化分子的分数与宏观光诱导应变和应力之间的关系，以建立光衰减的重要性。随后，模型液晶薄膜暴露在矩形照明波形下以模拟移动光源，从而产生表面波。所呈现的结果将波属性（即振幅、频率和相位滞后）与与移动光源、分子反式-顺式异构化反应和材料的粘弹性响应相关联的时间尺度相关联。提出了产生具有特定特征（幅度、相位）的表面波的设计指南。分子反顺异构化反应和材料的粘弹性响应。提出了产生具有特定特征（幅度、相位）的表面波的设计指南。分子反顺异构化反应和材料的粘弹性响应。提出了产生具有特定特征（幅度、相位）的表面波的设计指南。