Fluid wetting and penetration characteristics in T-shaped microchannels

TL;DR

This study investigates fluid wetting and penetration in T-shaped microchannels, revealing how geometry and flow velocity influence interface pinning and fluid distribution, with implications for improving microfluidic device design.

Contribution

It provides experimental insights into wetting mechanisms in microchannels, highlighting the effects of geometry on fluid behavior and introducing a novel image processing method.

Findings

Smaller crevice width enhances interface pinning.

Sharper edges increase fluid interface pinning.

Larger flow velocity promotes fluid penetration.

Abstract

A thorough understanding of media tightness in automotive electronics is crucial for ensuring more reliable and compact product designs, ultimately improving product quality. Concerning the fundamental characteristics of fluid leakage issues, the dynamic wetting and penetration behavior on small scales is of special interest and importance. In this work, four T-shaped microchannels with one inlet and two outlets are experimentally investigated in terms of contact angle dynamics and interface movement over time, generating novel insight into the wetting mechanisms and fluid distribution. With a main channel width of 1 mm, a crevice width of w = 0.3 mm, 0.4 mm and a rounding edge radius of r = 0.1 mm, 0.2 mm, the geometrical effects on the fluid penetration depth in the crevice and the interface edge pinning effect are analyzed quantitatively using an automated image processing procedure. It is found that the measured dynamic contact angles in all parts can be well described by molecular kinetic theory using local contact line velocities, even with local surface effects and abrupt geometry changes. Moreover, a smaller crevice width, a sharper edge and a larger flow velocity tend to enhance the interface pinning effect and prevent fluid penetration into the crevice. The rounding radius has a more significant effect on the interface pinning compared with crevice width. The experimental data and image processing algorithm are made publicly available.