In this study, a method for using arrays of mesoscale structures to modify the apparent optical properties of an opaque composite surface has been theoretically demonstrated to both raise and lower the apparent emissivity as compared to the intrinsic properties of the constitutive materials. For design problems where thermomechanical and optical material properties are both of importance, mesoscale surface structuring can greatly expand the design space. Analysis via the net radiosity method herein illustrates the ability to achieve a wide range of spectral apparent optical properties. Notably, a hexagonal array of spheres on a planar surface can raise the apparent emissivity of a planar surface by 50%. Conversely, a hexagonal enclosure of reradiating surfaces, realized by thin adiabatic walls, can reduce the apparent emissivity of a blackbody by half. As this method of modifying apparent optical properties utilizes structures much larger than the wavelengths of interest, the relationship between intrinsic planar emissivity, geometry, and apparent emissivity can be computed semi-analytically at low computational expense. Passive solar cooling, thermophotovoltaic cells, aerodynamic surfaces exposed to intense heating, and solar absorbers are presented as case studies that could benefit from the use of mesoscale structures on opaque surfaces to modify the apparent optical properties.

在这项研究中，一种使用中尺度结构阵列来改变不透明复合材料表面的表观光学特性的方法在理论上已被证明与本构材料的固有特性相比可以提高和降低表观发射率。对于热机械和光学材料特性都很重要的设计问题，中尺度表面结构化可以极大地扩展设计空间。通过本文中的净辐射度方法进行的分析说明了实现广泛的光谱表观光学特性的能力。值得注意的是，平面表面上的六边形球体阵列可以将平面表面的表观发射率提高 50%。相反，由薄绝热壁实现的再辐射表面的六边形外壳，可以将黑体的表观发射率降低一半。由于这种修改表观光学特性的方法使用的结构远大于感兴趣的波长，因此可以以低计算成本半解析地计算本征平面发射率、几何形状和表观发射率之间的关系。被动太阳能冷却、热光伏电池、暴露于强烈加热的空气动力学表面和太阳能吸收器作为案例研究提出，这些案例研究可以受益于在不透明表面上使用中尺度结构来修改表观光学特性。表观发射率可以以低计算成本进行半解析计算。被动太阳能冷却、热光伏电池、暴露于强烈加热的空气动力学表面和太阳能吸收器作为案例研究提出，这些案例研究可以受益于在不透明表面上使用中尺度结构来修改表观光学特性。表观发射率可以以低计算成本进行半解析计算。被动太阳能冷却、热光伏电池、暴露于强烈加热的空气动力学表面和太阳能吸收器作为案例研究提出，这些案例研究可以受益于在不透明表面上使用中尺度结构来修改表观光学特性。