The 2024 PhD Seminar in Memory of Prof. Shmuel and Mrs. Noemi Merhav – Theoretical Thermodynamic and Hydrodynamic Study of Liquids Under Negative Pressures.
When a liquid is subjected to a pressure below absolute zero, the phase change becomes favorable; however, the attractive interactions between the liquid molecules may hinder the phase change process. From a mechanical standpoint, the liquid stretches as the internal tension stresses, or negative hydrostatic pressures, develop in the liquid bulk. Liquids subjected to negative pressure are abundant and could be utilized in several industrial and medical applications. Some promising industrial innovations harness this phenomenon, while others seek to control and direct the nucleation occurring as the liquid relaxes back to a stable state.
Huygens made the first experimental observations of liquids under negative absolute pressures as early as 1662. Since then, numerous experimental apparatuses have been developed to generate negative pressure in liquids. However, a significant discrepancy exists between the maximum negative pressure a liquid can sustain before nucleation onset, as reported in different experiments. This gap, which may exceed 100 MPa, is yet unexplained, raising fundamental questions about the nature of liquids under extreme thermodynamic states and limiting the reliable application of this phenomenon.
Aiming to bridge the gap in current knowledge, we first focus on the surface tension-controlled, near-equilibrium growth of vapor bubbles. We present a new analysis for the early stages of vapor bubble growth in superheated liquids capable of capturing the early stages of bubble growth. We extend the analytic investigation by an extensive numerical study, enabling a detailed analysis of vapor bubble dynamics under highly oscillating negative pressures. The presented theoretical model may reveal possible future research pathways for better understanding the elusive and fascinating nature of liquids under negative pressure.
Work towards PhD degree under the supervision of Asst. Prof. Yuval Dagan and Prof. Eran Sher
