Surface tension of cavitation bubbles.

Area of Science:

• Thermodynamics
• Fluid Dynamics
• Materials Science

Background:

• Homogeneous cavitation is a fundamental phenomenon in fluid physics.
• Understanding cavitation in cryogenic fluids like liquid nitrogen and helium is crucial for various applications.
• Classical Nucleation Theory (CNT) provides a framework for studying bubble formation.

Purpose of the Study:

• To investigate homogeneous cavitation in liquid nitrogen and liquid helium.
• To compare experimental results with Classical Nucleation Theory (CNT).
• To explore the influence of temperature and bubble size on cavitation pressure and nucleation rates.

Main Methods:

• Monitoring fluid content in mesopores under controlled pressure changes.
• Studying cavitation in liquid nitrogen and normal liquid helium near their critical points and down to the triple point.
• Measuring nucleation rates as a function of liquid pressure for nitrogen.

Main Results:

• Cavitation pressure thresholds agree with CNT near the critical point for both fluids.
• Deviations from CNT at lower temperatures indicate reduced surface tension for bubbles < 2 nm.
• CNT holds for nitrogen down to the triple point when curvature dependence of surface tension is included.

Conclusions:

• Classical Nucleation Theory (CNT) is applicable to homogeneous cavitation in liquid nitrogen and helium, especially near the critical point.
• The study confirms the importance of considering surface tension's curvature dependence for nanoscale bubbles.
• Experimental findings support theoretical calculations for Lennard-Jones fluids regarding nucleation corrections.