Numerical Mesh Sensitivity Study of Flow-induced Acoustic Resonance in Closed Side-Branches

Abstract

Flow-induced acoustic resonance in closed side branches represents an important aeroacoustic phenomenon occurring in many industrial piping systems. Since the prediction of such coupled hydrodynamic–acoustic behavior is highly sensitive to numerical discretization, the present study investigates the influence of mesh resolution, near-wall treatment, and inlet velocity profile generation on the accuracy of CFD simulations of closed side-branch resonance. A precursor-pipe approach was used to generate a sufficiently developed inlet velocity profile prior to the main simulations, while several precursor meshes with progressively refined cell sizes and near-wall resolution were evaluated to assess profile convergence. The main simulations were performed on four computational meshes with increasing refinement, including a locally adapted mesh in the shear-layer region, for inlet velocities of 10 m/s, 14 m/s, and 18 m/s. Pressure signals were monitored at the closed end of the branch and at multiple locations within the shear layer to identify dominant oscillation modes and evaluate the coupled resonance behavior. The results highlight the importance of consistent inlet profile generation, adequate near-wall resolution, and local shear-layer refinement for accurate prediction of flow-induced resonance phenomena in closed side-branch configurations.