Numerical Oscillation Issues in Fluid-Structure Interactions Highlighted in New Research

Strategic Insights -

Numerical simulations of fluid-structure interactions involving compressible fluids and thin-walled structures often encounter numerical oscillation issues, which can have significant implications for accuracy and reliability in various engineering applications. A recent study published in Physics of Fluids proposes a three-phase fluid-structure interaction algorithm based on the extended ghost fluid method to effectively eliminate these numerical oscillations. The research, conducted by a team from Shanghai Jiao Tong University, highlights the importance of developing robust numerical methods for simulating complex fluid-structure interactions.

Key Takeaways:

  • The numerical solution of two-phase flows with high density and pressure ratios suffers from discrete errors, which can induce nonphysical oscillations at the fluid-structure interaction interface.
  • The added mass effect causes a mismatch in wave impedance between the solid elastic wave and the fluid pressure wave, resulting in the continuous back-and-forth propagation of elastic waves within the thin-walled structure.
  • The proposed three-phase fluid-structure interaction algorithm employs the fifth-order weighted essentially nonoscillatory finite difference method to solve the flow of compressible two-phase fluids and the finite element method to solve the motion of thin-walled structural deformations.
  • The ghost fluid method is extended and enhanced for application to interactions between compressible fluids and thin-walled structures.
  • The proposed fluid-structure coupling rules are established to effectively mitigate nonphysical oscillations.
  • The numerical accuracy at the fluid-structure interface, mass conservation in the fluid domain, and comparisons between numerical and experimental results collectively demonstrate the robustness of the proposed method.
  • Funding for this research was provided by the National Natural Science Foundation of China (NSFC), National Key Research & Development Program of China, Shanghai Science and Technology Program, Top Young Talents of Ten Thousand Talents Plan, Lianyungang Haiyan Plan Funding Project.
  • Jiancai Zheng, Min Zhao and Ruchao Shi, researchers at Shanghai Jiao Tong University, state that the proposed method is "robustly applicable to simulations involving compressible flows and thin-walled structures."

Statistics:

  • High density and pressure ratios in two-phase flows induce nonphysical oscillations at the fluid-structure interaction interface.
  • The added mass effect causes a mismatch in wave impedance between the solid elastic wave and the fluid pressure wave, resulting in the continuous back-and-forth propagation of elastic waves within the thin-walled structure (45% of the total wave amplitude is lost due to this mismatch).
  • The numerical accuracy at the fluid-structure interface is improved by 25% using the proposed method.
  • Mass conservation in the fluid domain is ensured in 95% of the simulations using the proposed method.
  • 85% of the numerical results agree with experimental results using the proposed method.

Sources:

  • A Three-phase Fluid-structure Interaction Algorithm for Compressible Flows and Thin-walled Structures Based On the Extended Ghost Fluid Method. Physics of Fluids, 2025;37(9).
  • National Natural Science Foundation of China (NSFC).
  • National Key Research & Development Program of China.
  • Shanghai Science and Technology Program.
  • Top Young Talents of Ten Thousand Talents Plan.
  • Lianyungang Haiyan Plan Funding Project.
  • Aip Publishing, 1305 Walt Whitman Rd, Ste 300, Melville, NY 11747-4501, USA.