Kim, Jungchul Moon, Myoung-Woon Lee, Kwang-Ryeol Mahadevan, L. Kim, Ho-Young 2024-01-20T15:34:42Z 2024-01-20T15:34:42Z 2021-09-05 2011-12-20 0031-9007 https://pubs.kist.re.kr/handle/201004/129708 Writing with ink involves the supply of liquid from a pen onto a porous hydrophilic solid surface, paper. The resulting linewidth depends on the pen speed and the physicochemical properties of the ink and paper. Here we quantify the dynamics of this process using a combination of experiment and theory. Our experiments are carried out using a minimal pen, a long narrow tube that serves as a reservoir of liquid, which can write on a model of paper, a hydrophilic micropillar array. A minimal theory for the rate of wicking or spreading of the liquid is given by balancing the capillary force that drives the liquid flow and the resistance associated with flow through the porous substrate. This allows us to predict the shape of the front and the width of the line laid out by the pen, with results that are corroborated by our experiments. English AMER PHYSICAL SOC RADIAL CAPILLARY IMBIBITION SURFACES LIQUID Hydrodynamics of Writing with Ink Article 10.1103/PhysRevLett.107.264501 1 PHYSICAL REVIEW LETTERS, v.107, no.26 PHYSICAL REVIEW LETTERS 107 26 scie scopus 000298607400004 2-s2.0-84455207869 Physics, Multidisciplinary Physics Article RADIAL CAPILLARY IMBIBITION SURFACES LIQUID Ink Writing Hydrophilic DLC