An understanding in microfluidics is essential in aerospace engineering. The formation of and interactions between gas bubbles, which are generated through multiphase flows in microchannels, are especially relevant in aerospace applications. Due to microgravity conditions in space, however, controlling bubble formation remains a challenge. Parameters such as surface wettability can significantly alter bubble generation rates.

Recent research has shown interest in hybrid surfaces, such as those observed on the Namib beetle. Inspired by how the beetle uses its simultaneously superhydrophobic and hydrophilic surface to collect water, Mousavi et al. investigated bubble formation dynamics with a focus on hybrid wettability.

“In microgravity, the control of fluid behavior becomes significantly more complex and energy-consuming,” said author Bok Jik Lee. “By emulating the beetle’s efficient water collection method, we aim to create a system capable of effectively controlling the complexities of fluid behavior in space environments, thereby combining nature’s ingenious designs with advanced engineering techniques.”

The authors tracked the interface of a T-junction microchannel under microgravity conditions. By simulating scenarios ranging from hydrophobic to superhydrophobic conditions and observing the impact of different contact angles, they found that hybrid wettability can stabilize slug flow, reduce flow instability, and influence bubble generation rates.

The authors aim to continue improving the efficiency and reliability of space-based fluid systems.

“Future projects could include manipulating wall contact angles and employing suitable constant angle distributions to influence Taylor flow regimes at a constant mass flow rate ratio,” said Lee. “This approach suggests a suitable method for altering the dynamic behavior of fluids in microgravity and can lead to more precise control of multiphase flow systems in space environments.”

Source: “Bubble generation mechanisms in microchannel under microgravity and heterogeneous wettability,” by S. Mahmood Mousavi, Jongkwon Lee, Bok Jik Lee, Dorrin Jarrahbashi, Nader Karimi, and Salah A. Faroughi, Physics of Fluids (2024). The article can be accessed at https://doi.org/10.1063/5.0188262.