arXiv subjects

Taiyang Wang

Publications and source records attributed to Taiyang Wang.

4 recordsLinked to original sources

arXiv2026

Direct numerical simulation of particle-laden flow in a linear compressor cascade: Unsteady boundary-layer effects on blade erosion

We perform point-particle direct numerical simulations (PP-DNS) of particle-laden flow through a linear compressor cascade subjected to synthetic freestream turbulence. Monodisperse particles are advanced in a one-way coupled Eulerian-Lagrangian framework with drag-only dynamics. We quantify blade-particle collisions and resulting blade erosion based on high-fidelity data, and the erosion hotspots are predicted near the leading edge and over the pressure side. On the pressure side, for intermediate Stokes numbers, the onset of collisions correlates with elevated boundary-layer intermittency associated with bypass transition, whereas for larger particles impacts occur farther upstream with a higher probability of multiple rebounds. On the suction side, sparse collisions appear only for the smallest particles and are phase-modulated by separation-induced vortex shedding. Joint distributions of impact velocity and angle show that leading-edge impacts are faster and span wider angles than pressure-side impacts, explaining their greater erosive severity. The present results highlight the role of unsteady boundary-layer dynamics in affecting erosion in compressor cascades.

physics.flu-dyn↗

arXiv2026

Asymmetric particle transport in turbulent flows within concentric annular ducts

We present the first direct numerical simulations of particle-laden turbulent flow in concentric annuli to investigate the effects of transverse curvature over a range of Stokes numbers. The results demonstrate that transverse curvature induces asymmetric radial transport, with particles preferentially drifting toward the outer wall. Unlike canonical planar flows where turbophoresis universally drives near-wall accumulation, the present study identifies a distinct physical regime at the convex inner wall where centrifugal effect competes with turbophoresis. As a consequence, significant particle depletion is observed near the inner wall under strong curvature, and the transient concentration field exhibits a non-monotonic evolution, with the overshoot generally being more evident at higher Stokes numbers. By deriving a transport equation and applying Sturm-Liouville modal analysis, we identify the competition between asymmetric transport modes with different decay rates as the physical mechanism driving this non-monotonic evolution, and establish a reduced-order model that captures the dynamics of the particle concentration near the walls.

physics.flu-dyn↗

arXiv2026

Low-wavenumber wall pressure fluctuations in turbulent flows within concentric annular ducts

Compressible direct numerical simulations of turbulent channel flows in concentric annular ducts of height $2\delta$ are performed to study the low-wavenumber wall pressure fluctuations (WPF) over cylindrical walls at a bulk Mach number $M_b = 0.4$ and bulk Reynolds number $Re_b=3000$. The radius of the inner cylinder $R$ is varied between $0.2\delta$, $\delta$, $2\delta$ and $\infty$. As $R$ decreases, the one-point power spectral density of the WPF decreases at intermediate but increases at high frequencies. When $R$ decreases, the 1D (streamwise) wavenumber-frequency spectrum of the WPF decreases at high wavenumbers. At low wavenumbers, however, as $R$ reduces to $0.2\delta$ the 1D wavenumber-frequency spectrum exhibits multiple spectral peaks whose strengths increase with frequency. Examination of the 2D wavenumber-frequency spectra shows that these represent acoustic duct modes that closely match theoretical predictions. The acoustic modes of higher radial orders exhibit increasingly high amplitude on the inner than on the outer walls. The low-wavenumber components of the $0$th-order (azimuthal) 2D wavenumber-frequency spectrum are of great importance in practice, and their magnitude increases as $R$ reduces; this increase is increasingly pronounced at higher frequencies. Analytical modelling and numerical validation show that this increase appears to arise from the ``geometric'' effects connected with the Green's function, and they are generated mainly by radial and azimuthal disturbances. Disturbances closer to the wall are shown to be increasingly important in WPF generation as $R$ reduces, which highlights a potential in WPF control using wall treatment on thin cylinders.

physics.flu-dyn↗

arXiv2025

A high-fidelity and efficient framework for point-particle direct numerical simulation based on multi-block overset grids

In this work, we present a high-fidelity and efficient point-particle direct numerical simulation framework based on a multi-block overset curvilinear grid system, enabling large-scale Lagrangian particle tracking in complex geometries with high-order accuracy and low computational cost. To handle the multi-domain topological challenges inherent in such configurations, we develop an efficient particle storage and redistribution framework leveraging overset grid techniques. In particular, two optimization strategies have been proposed for particle redistribution: one is an innovative inter-block mapping within overlapping zones, and the other is a fast search-locate algorithm based on particle velocity. Together, these approaches significantly reduce the particle tracking overhead, especially for particles passing through interfaces between overlapping grid blocks. Moreover, the accuracy and robustness of the present framework are rigorously validated through various cases, including massless particle trajectories, one- and two-way coupled simulations. Specifically, we demonstrate the framework's applicability to the direct numerical simulation of particle-laden flow in a linear compressor cascade at engine-relevant conditions, showcasing its capability to resolve complex particle dynamics in turbomachinery configurations with low computational costs.

physics.flu-dyn↗