Impact of Top Surface Boundary Conditions on Internal Solitary Waves

A new study on Physics - Fluids has been released, providing insights into the impact of top surface boundary conditions on internal solitary waves in numerical simulations. The research, conducted by a team from Dalian University of Technology, explores the effects of rigid-lid and free-surface boundary conditions on the dynamics of internal solitary waves. The study reveals that under certain conditions, the choice of boundary condition significantly alters the wave profiles, phase speeds, and flow fields of internal solitary waves.

Key Takeaways:

• The rigid-lid condition simplifies model setup and reduces computational cost by fixing the upper surface, but it may not accurately represent ocean surface physics.
• The free-surface condition more accurately represents ocean surface physics, but it requires higher computational costs.
• Under large density differences, the choice of boundary condition significantly alters internal solitary wave profiles, phase speeds, and flow fields.
• For a small density difference close to the real ocean (e.g., ρ(1)/ρ(2)=1000/1025), both rigid-lid and free-surface conditions yield indistinguishable results across key internal solitary wave characteristics.
• The Miyata-Choi-Camassa theory solution proves suitable as an initial wave profile condition, applicable for both small and large wave amplitudes.
• The rigid-lid condition achieves comparable accuracy to the free-surface condition in predicting internal solitary wave characteristics for oceanographically relevant scenarios.

Statistics:

• Large density differences: 1000/1025
• Small density difference: 1000/1025
• Initial wave amplitudes: small and large
• Depth ratios: varying

Sources:

• The Effect of Top Surface Boundary Conditions On Internal Solitary Waves In Numerical Simulations. Physics of Fluids, 2025;37(9).
• Dalian University of Technology. School of Naval Architecture and State Key Lab Struct Anal Optimizat & Cae Software.
• National Natural Science Foundation of China (NSFC).
• National Key Research & Development Program of China.