Morphological evolution of splashing drop revealed by interpretation of explainable artificial intelligence

Abstract

This study reveals the morphological evolution of a splashing drop by a newly proposed feature extraction method, and a subsequent interpretation of the classification of splashing and non-splashing drops performed by an explainable artificial intelligence (XAI) video classifier. Notably, the values of the weight matrix elements of the XAI that correspond to the extracted features are found to change with the temporal evolution of the drop morphology. We compute the rate of change of the contributions of each frame with respect to the classification value of a video as an importance index to quantify the contributions of the extracted features at different impact times to the classification. Remarkably, the rate computed for the extracted splashing features of ethanol and 1 cSt silicone oil is found to have a peak value at the early impact times, while the extracted features of 5 cSt silicone oil are more obvious at a later time when the lamella is more developed. This study provides an example that clarifies the complex morphological evolution of a splashing drop by interpreting the XAI.