Large-eddy simulation of hydrodynamic noise from turbulent flows past an axisymmetric hull using high-order schemes

TL;DR

This study employs high-order wall-modeled large-eddy simulation combined with acoustic analogy to analyze hydrodynamic noise from turbulent flows around an axisymmetric hull, validating the approach with benchmark tests and applying it to complex flow scenarios.

Contribution

The paper develops and validates a high-order numerical model for simulating turbulent flow and hydrodynamic noise around an axisymmetric hull at high Reynolds numbers, improving accuracy over previous methods.

Findings

Accurately predicts pressure coefficients and velocity fluctuations around the hull.

Identifies low-frequency broadband pressure spectra on the hull surface.

Reveals the acoustic directivity pattern with a dipole shape in the far field.

Abstract

In this paper, wall-modeled large-eddy simulation (WMLES) is carried out with Ffowcs-Williams and Hawkings (FW-H) acoustic analogy to investigate the turbulent flow and hydrodynamic noise of an axisymmetric body of revolution. We first develop the numerical model based on high-order schemes and validate it by benchmark test of the turbulent flow around a circular cylinder at Re=10000. It demonstrates the capability of the present scheme to capture the primary flow patterns and the acoustic noise in the far field. Then, we conduct the numerical simulation for the turbulent flows around the DARPA SUBOFF without appendages at the Reynolds number of Re=1.2*10^7. The numerical results such as pressure coefficients and velocity fluctuations, are accurately predicted by the present model, which shows closer agreement with the experimental data than available WMLES solutions in the literature. For the parallel midbody of the hull, the wall pressure fluctuation reveals a low-frequency broadband spectrum with the majority of signal energy. The surface fluctuating pressure spectrum scales to the power of Strouhal number at the different locations, which is consistent with those in the turbulent boundary layer of the plate flows and airfoils. Moreover, the acoustic signature in the far field is investigated where the lowest sound pressure level (SPL) occurs in the upstream and downstream directions while the highest is found in the mid-parallel plane. SPLs are relatively close in the region of high acoustic pressure at the transverse plane of x/D=0, which exhibits a maximum difference of 1.2 dB between locations at different angles. In the vertical plane at z/D=0, the directivity plot reveals a symmetrical dipole pattern with vertical fluctuations stronger than the streamwise fluctuations.