Research data supporting "Cleaning of thick viscoplastic soil layers by impinging water jets"

The data set shows videos from experiments described in the paper, where water jets (2 mm or 3 mm diameter) impinge vertically downwards on to a Perspex or glass plate coated with a layer of a soft solid soil. The jet impinges normally, so the soil is removed in a roughly cricular pattern. The plates are transparent. Removal of the soil was monitored from above using a Go Pro Hero digital camera operating in video mode: removal of the soil was monitored from below using a Canon digital SLR, again operating in video mode, focused on a mirror located beneath the target plate and angled at 45 degrees to the horizontal. These videos were used to characterise removal behaviour, and to calculate the size of the cleared area. For the latter, individual frames were digitised in Matlab and the average radius of the cleared region calculated. The average radius viewed from above was labelled 'b' and that from below was labelled 'a': the labels were chosen for consistency with previous studies which only considered removal monitored from below. The three sets show examples of different removal behaviour: in 'cratering', material is cleared away from the point of impingement with well defined top and bottom boundaries. In 'blistering', observed with thick layers, the liquid initially penetrates the soil layer and generates a cavern, with a confining shell of removed soil - this 'blister' grows with time and eventually the confining shell ruptures. In 'walling', following blister rupture, the confining shell retains its coherence and moves outwards with the removal front.

本数据集收录了某学术论文中所述实验的视频素材。实验中，直径为2毫米或3毫米的水流射流垂直向下冲击覆盖有软固体土壤层的有机玻璃（Perspex）或玻璃板。射流垂直冲击靶板，使得土壤以近似圆形的模式被清除。靶板为透明材质。实验采用两种方式监测土壤清除过程：一是通过工作于视频模式的GoPro Hero数码相机从上方拍摄记录；二是通过佳能（Canon）数码单反相机以视频模式从下方拍摄，该相机对准位于靶板下方、与水平面成45度角的反射镜取景。上述视频用于表征土壤清除行为，并计算清除区域的尺寸。针对尺寸计算环节，研究人员在Matlab中对单帧图像进行数字化处理，并计算清除区域的平均半径：从上方观测得到的平均半径标记为`b`，从下方观测得到的平均半径标记为`a`，该命名规则与此前仅针对下方监测清除过程的相关研究保持一致。本次数据集包含三类不同清除行为的示例：1. 凹坑型（cratering）：冲击点处的物料被清除，形成边界清晰的顶面与底面；2. 鼓泡型（blistering）：在较厚土层中可观察到该现象，液体首先穿透土层形成空腔，同时周围土壤被移除形成约束壳层——该“鼓泡”随时间不断扩大，最终约束壳层发生破裂；3. 护壁型（walling）：该现象出现在鼓泡破裂后，约束壳层保持结构完整性，并随清除前沿向外移动。