Drop impact on thin powder layers: pattern formation by air entrapment

Impact of drops on thin powder layers displaces the powder particles radially outward producing shallow craters with thick rims, for example, as observed on dust layers on the floor. Here, we report that the patterns formed on thin powder layers by drop impact are not limited to such crater-like one...

Full description

Saved in:
Bibliographic Details
Published in:Soft matter 2020-02, Vol.16 (5), p.1342-1348
Main Authors: Sharma, Meenakshi, Gopu, Maheshwar, George, Jijo Easo, Gupta, Saumya, Mampallil, Dileep
Format: Article
Language:English
Subjects:
Entrapment
Pattern formation
Powder
Thin films
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Impact of drops on thin powder layers displaces the powder particles radially outward producing shallow craters with thick rims, for example, as observed on dust layers on the floor. Here, we report that the patterns formed on thin powder layers by drop impact are not limited to such crater-like ones. Instead, depending upon the layer properties, disc or disc-plus-ring shaped patterns are formed at the impact point. We show that air entrapment and micro-bubble formation during the drop impact result in the formation of such patterns. Based on high-speed imaging, scaling analyses, and measurements with various liquids and powder layers, we propose a mechanism for the formation of such patterns. The phenomenon that we report can open further investigations on drop impact on the granular matter. Drops impacting on thin powder layers can form fascinating patterns of powder particles by the interplay of processes such as micro-bubble generation and large air-disc entrapment.
ISSN:1744-683X
1744-6848
DOI:10.1039/c9sm01887e