{'fraction_non_alphanumeric': 0.011641443538998836, 'fraction_numerical': 0.0, 'mean_word_length': 4.8108108108108105, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Horizontal flow and surface patterns in a vertically vibrated annular granular layer.

A set of experiments was carried out on the motion of granular materials in a vertically vibrated annular system with a sawtooth-shaped base. We observed the coexistence of granular flow and surface patterns such as periodic subharmonic waves and kink pairs. Different patterns can transit each other as control parameters vary. The flow varies with space and time, and oppositely directed flows can occur at different levels and different moments. The magnitude and direction of the flow depend on the parameters defining the system in a complex manner. The motion of the patterns relates to the granular flow in a different way from that in which the wave in an ordinary fluid relates to the moving fluid. A preliminary explanation is given to our experimental findings.