@unpublished{yu2025transmission,
  author = {Yu, Haocheng and Ahuja, Krishan K and Sankar, Lakshmi N and Bryngelson, Spencer H},
  title = {Transmission of high-amplitude sound through leakages of ill-fitting earplugs},
  note = {arXiv preprint arXiv:2510.16355},
  year = {2025},
  doi = {2510.16355},
  file = {}
}

High sound pressure levels (SPL) pose notable risks in loud environments, particularly due to noise-induced hearing loss. Ill-fitting earplugs often lead to sound leakage, a phenomenon this study seeks to investigate. To validate our methodology, we first obtained computational and experimental acoustic transmission data for stand-alone slit resonators and orifices, for which extensive published data are readily available for comparison. We then examined the frequency-dependent acoustic power absorption coefficient and transmission loss (TL) across various leakage geometries, modeled using different orifice diameters. Experimental approaches spanned a frequency range of 1–5 kHz under SPL conditions of 120–150 dB. Key findings reveal that unsealed silicone rubber earplugs demonstrate an average TL reduction of approximately 18 dB at an overall incident SPL (OISPL) of 120 dB. Direct numerical simulations further highlight SPL-dependent acoustic dissipation mechanisms, showing the conversion of acoustic energy into vorticity in ill-fitting earplug models at an OISPL of 150 dB. These results highlight the role of earplug design for high-sound-pressure-level environments.

@unpublished{yu2025energy,
  author = {Yu, Haocheng and Chu, Tianyi and Bryngelson, Spencer H},
  title = {Energy dissipation mechanisms in an acoustically-driven slit},
  note = {arXiv preprint arXiv:2512.19507},
  year = {2025},
  doi = {2512.19507},
  file = {}
}

We quantify how incident acoustic energy is converted into vortical motion and viscous dissipation for a two-dimensional plane-wave passing through a slit geometry. We perform direct numerical simulations over a broad parameter space in incident sound pressure level (ISPL), Strouhal number (St), and Reynolds number (Re). Spectral proper orthogonal decomposition (SPOD) yields energy-ranked coherent structures at each frequency, from which we construct mode-by-mode fields for spectral kinetic energy (KE) and viscous loss (VL) components to examine the mechanisms of acoustic absorption. At ISPL=150dB, the acoustic-hydrodynamic energy conversion is highest when the acoustic displacement amplitude is comparable to the slit thickness, corresponding to a Keulegan-Carpenter number of order unity. In this regime, the oscillatory boundary layer undergoes periodic separation, resulting in vortex shedding that dominates acoustic damping. VL accounts for 20-60% of the KE contribution. For higher acoustic frequencies, the confinement of the Stokes layer produces X-shaped near-slit modes, reducing the total energy input by approximately 50%. The influence of Re depends on amplitude. At ISPL=150dB, larger Re values correspond to suppressed broadband fluctuations and sharpened harmonic peaks. At ISPL = 120dB, the boundary layers remain attached, vortex shedding is weak, absorption monotonically scales with viscosity, and the Re- and St-dependencies become comparable. Across all conditions, more than 99% of the VL is confined to a compact region surrounding the slit mouth. The KE-VL spectra describe parameter regimes that enhance or suppress acoustic damping in slit geometries, providing a physically interpretable basis for acoustic-based design.

@article{wilfong2026mfc,
  title = {MFC 5.0: An exascale many-physics flow solver},
  author = {Wilfong, Benjamin and Le Berre, Henry A and Radhakrishnan, Anand and Gupta, Ansh and Vickers, Daniel J and Vaca-Revelo, Diego and Adam, Dimitrios and Yu, Haocheng and Lee, Hyeoksu and Chreim, Jose Rodolfo and others},
  journal = {Computer Physics Communications},
  volume = {322},
  number = {},
  pages = {110055},
  year = {2026},
  doi = {10.1016/j.cpc.2026.110055},
  publisher = {Elsevier}
}

Many problems of interest in engineering, medicine, and the fundamental sciences rely on high-fidelity flow simulation, making performant computational fluid dynamics solvers a mainstay of the open-source software community. Previous work MFC 3.0 was made a published, documented, and open-source solver via Bryngelson et al. Comp. Phys. Comm. (2021) with numerous physical features, numerical methods, and scalable infrastructure. MFC 5.0 is a significant update to MFC 3.0, featuring a broad set of well-established and novel physical models and numerical methods, as well as the introduction of GPU and APU (or superchip) acceleration. We exhibit state-of-the-art performance and ideal scaling on the first two exascale supercomputers, OLCF Frontier and LLNL El Capitan. Combined with MFC’s single-accelerator performance, MFC achieves exascale computation in practice, and achieved the largest-to-date public CFD simulation at 200 trillion grid points as a 2025 ACM Gordon Bell Prize finalist. New physical features include the immersed boundary method, N-fluid phase change, Euler–Euler and Euler–Lagrange sub-grid bubble models, fluid-structure interaction, hypo- and hyper-elastic materials, chemically reacting flow, two-material surface tension, magnetohydrodynamics (MHD), and more. Numerical techniques now represent the current state-of-the-art, including general relaxation characteristic boundary conditions, WENO variants, Strang splitting for stiff sub-grid flow features, and low Mach number treatments. Weak scaling to tens of thousands of GPUs on OLCF Summit and Frontier and LLNL El Capitan achieves efficiencies within 5% of ideal to over 90% of their respective system sizes. Strong scaling results for a 16-times increase in device count show parallel efficiencies over 90% on OLCF Frontier. MFC’s software stack has undergone further improvements, including continuous integration, which ensures code resilience and correctness through over 300 regression tests; metaprogramming, which reduces code length while maintaining performance portability; and code generation for computing chemical reactions

@article{goldstein2026,
  author = {Goldstein, Bailey and Ramsey, David N and Yu, Haocheng and Bryngelson, Spencer H and Ahuja, Krishan K},
  year = {2026},
  title = {Performance of Sharply Bent Acoustic Resonators at High Sound Levels},
  journal = {AIAA Journal},
  pages = {In-press}
}

We present a numerical investigation of high-pressure sound waves through small orifice openings, focusing on earplug leakage. Our long-term goal is to improve earplug design in loud environments. Our contribution to earplug leak mechanics builds upon prior art that identifies the conversion of high-amplitude sound when passing through small openings into vorticity as a dominant dissipation mechanism in resonant acoustic liners. This quantifies the rate of kinetic energy transfer to the shed vortices, which can exceed the acoustic viscous dissipation rate. This provides a detailed understanding of the energy dissipation mechanisms when high-pressure sound waves propagate through small leaks.

@inproceedings{goldstein2025,
  author = {Goldstein, Bailey and Ramsey, David N and Yu, Haocheng and Bryngelson, Spencer H and Ahuja, Krishan K},
  year = {2025},
  title = {Performance of Sharply Bent Acoustic Resonators at High Sound Levels},
  booktitle = {AIAA AVIATION FORUM AND ASCEND 2025},
  address = {Las Vegas, NV},
  pages = {3748}
}

We present a numerical investigation of high-pressure sound waves through small orifice openings, focusing on earplug leakage. Our long-term goal is to improve earplug design in loud environments. Our contribution to earplug leak mechanics builds upon prior art that identifies the conversion of high-amplitude sound when passing through small openings into vorticity as a dominant dissipation mechanism in resonant acoustic liners. This quantifies the rate of kinetic energy transfer to the shed vortices, which can exceed the acoustic viscous dissipation rate. This provides a detailed understanding of the energy dissipation mechanisms when high-pressure sound waves propagate through small leaks.

@inproceedings{yu2024,
  author = {Yu, Haocheng and Ahuja, Krishan K and Sankar, Lakshmi N and Bryngelson, Spencer H},
  year = {2024},
  title = {Numerical investigation of leakage of high-amplitude sound in ill-fitting earplugs},
  booktitle = {AIAA AVIATION FORUM AND ASCEND 2024},
  address = {Las Vegas, NV},
  pages = {4391}
}

We present a numerical investigation of high-pressure sound waves through small orifice openings, focusing on earplug leakage. Our long-term goal is to improve earplug design in loud environments. Our contribution to earplug leak mechanics builds upon prior art that identifies the conversion of high-amplitude sound when passing through small openings into vorticity as a dominant dissipation mechanism in resonant acoustic liners. This quantifies the rate of kinetic energy transfer to the shed vortices, which can exceed the acoustic viscous dissipation rate. This provides a detailed understanding of the energy dissipation mechanisms when high-pressure sound waves propagate through small leaks.

@inproceedings{yu2022,
  author = {Yu, Haocheng and Filloon, Julia and Ramsey, David N and Ahuja, Krishan K and Sankar, Lakshmi N},
  year = {2022},
  title = {Modelling and testing sound leakage in ill-fitting earplugs},
  booktitle = {AIAA SCITECH 2022},
  address = {San Diego, CA},
  pages = {2562}
}

Safety earmuffs and earplugs are often worn by personnel exposed to high sound pressure levels, such as flight deck crews on aircraft carriers, in order to prevent noise-induced hearing loss. Personal protective equipment, specifically earplug-style hearing protection, are not typically molded to the ear of the wearer. As a result, small spaces, which serve as flanking paths or leakage for sound, can exist between the ear canal wall and earplug due to differences in geometry between individual ear canals. The purpose of this work is to model and study the frequency-dependent acoustic transmission loss (TL) of these flanking paths by varying their diameter and shape using quantified representative small orifices in 3D printed plates, and investigating how flanking paths can affect the noise blockage performance of three commercial earplugs made of silicone putty, soft foam, or rubber silicone sealed with and without a petroleum jelly (Vaseline). The frequency-dependent acoustic TL is measured utilizing a two-sided, two-microphone TL tube using an impulse method. Analytical modeling predictions based on circular axisymmetric models of the flanking paths are compared with computed COMSOL numerical modeling and experimental results.