Inorganic precipitation reactions can self-organize a multitude of complex macroscopic patterns. The striking precipitate tubes in chemical gardens are a classic example which recently have been studied in the context of spatially confined, thin layers. Here, we introduce stationary, spatially periodic perturbations to this type of pattern formation by using computerized milling procedures for the production of nonplanar Hele-Shaw cells. The injection of NiCl₂ solutions into NaOH-filled cells forms precipitate patterns that include lobes, deformed circles, worms, and filaments. Of these structure types, lobes and deformed circles respond most strongly to the introduced height variations, whereas filaments—the closest analog of chemical garden tubes—are essentially unresponsive. The effect of the perturbations also strongly depends on the density difference between the injected and displaced fluids and involves preferred penetration directions for lowered regions. Our experimental technique and observations could be of relevance to research on fluid flow and precipitation reactions in sedimentary rock with inhomogeneous porosities.

中文翻译：

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正弦波高度变化小的Hele-Shaw单元中的沉淀模式

无机沉淀反应可以自组织许多复杂的宏观模式。化学园中引人注目的沉淀管是一个经典的例子，最近在空间受限的薄层环境中进行了研究。在这里，我们通过使用计算机化的铣削程序生产非平面Hele-Shaw细胞，将固定的，空间周期性的扰动引入到这种类型的图案形成中。NiCl ₂的注入溶液填充到充满NaOH的细胞中会形成沉淀图案，包括叶，变形的圆，蠕虫和细丝。在这些结构类型中，波瓣和变形的圆对引入的高度变化反应最强烈，而细丝（化学花园管的最接近的类似物）基本上没有反应。扰动的影响还强烈取决于注入和驱替流体之间的密度差，并且涉及较低区域的首选穿透方向。我们的实验技术和观察结果可能与研究非均质孔隙沉积岩中的流体流动和沉淀反应有关。