Spontaneous imbibition experiment in newspaper sheets

Area of Science:

• Physics of complex fluids
• Surface science
• Materials science

Background:

• Spontaneous imbibition is a fundamental process in porous media, crucial for applications like printing and fluid absorption.
• Understanding the ink-paper interface dynamics is key to controlling fluid spreading and pattern formation.

Purpose of the Study:

• To investigate the behavior of the ink-paper interface during spontaneous imbibition.
• To characterize the interface roughness as a function of time and paper orientation.
• To determine the multiaffine nature of the interface evolution.

Main Methods:

• Conducted spontaneous imbibition experiments with ink on paper.
• Quantified interface roughness using growth (beta) and Hurst (H) exponents derived from the root mean square interface width (W).
• Analyzed the qth order height-height correlation function to calculate the H{q} scaling exponent.

Main Results:

• The Hurst (H) and H{q} scaling exponents were found to be dependent on the orientation of the paper sheets.
• The growth exponent (beta) showed no dependence on paper orientation.
• The ink-paper interface consistently exhibited multiaffine characteristics throughout the imbibition process.

Conclusions:

• Paper orientation significantly influences the statistical properties of the ink-paper interface during spontaneous imbibition.
• The observed multiaffine behavior suggests complex, orientation-dependent growth dynamics at the interface.
• These findings contribute to a deeper understanding of fluid transport in anisotropic porous media.