Localized defect states of liquid surface waves in non-Bragg periodic structures are investigated experimentally and validated numerically using the finite element method. Two parameters are considered, one is the position of the defect along the full length of the structure and the other is the filling fraction achieved by calibrating the length of the structures as a factor of the periodic length. It is well known that defects in periodic structures always cause the transparency modes inside the stopbands and may localize the wave energy in the nearfield of the defect element. Here, we examine the interplay between the structure transmission in the defect mode and the localization around the defect element. The experimental and numerical results show that the magnitude of the transmission coefficient of the defect mode can be affected by the position of the defect in the overall structure. However, the frequency of the defect mode is found to be independent of the defect location. It is further established that the mode frequency can be controlled via the manipulation of the effective filling fraction of the periodic structures with a positive gradient. These findings enrich our knowledge of defect mode parameters for liquid surface waves and due to the universal nature of wave phenomena, the findings would open new avenues of wave energy control and manipulation applications.

实验研究了非布拉格周期结构中液体表面波的局部缺陷状态，并使用有限元方法进行了数值验证。考虑了两个参数，一个是缺陷在结构全长上的位置，另一个是通过将结构的长度作为周期长度的一个因素进行校准而达到的填充率。众所周知，周期性结构中的缺陷总是会引起阻带内的透明模式，并且可能会将波能局域在缺陷元素的近场中。在这里，我们检查缺陷模式下的结构传输与缺陷元素周围的定位之间的相互作用。实验和数值结果表明，缺陷模式的透射系数的大小会受到整个结构中缺陷位置的影响。但是，发现缺陷模式的频率与缺陷位置无关。进一步确定的是，可以通过以正梯度对周期结构的有效填充率进行控制来控制模式频率。这些发现丰富了我们对液面波缺陷模式参数的了解，并且由于波现象的普遍性，这些发现将为波能控制和操纵应用开辟新的途径。进一步确定的是，可以通过以正梯度对周期结构的有效填充率进行控制来控制模式频率。这些发现丰富了我们对液面波缺陷模式参数的了解，并且由于波现象的普遍性，这些发现将为波能控制和操纵应用开辟新的途径。进一步确定的是，可以通过以正梯度对周期结构的有效填充率进行控制来控制模式频率。这些发现丰富了我们对液面波缺陷模式参数的了解，并且由于波现象的普遍性，这些发现将为波能控制和操纵应用开辟新的途径。