Aeroacoustic simulation of broadband sound generated from low-Mach-number flows using a lattice Boltzmann method

Kusano, Kazuya; Yamada, Kazutoyo; Furukawa, Masato

doi:10.1016/j.jsv.2019.115044

Cited by 25 publications

(10 citation statements)

References 39 publications

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“…Furthermore, to avoid the sound reflection from the inlet and outlet boundaries, the absorbing regions were installed near the inlet and outlet boundaries. In these regions, pressure fluctuations were dumped artificially [7]. Stationary walls, such as the casing, were considered based on the bounce-back rule.…”

Section: Boundary Conditionsmentioning

confidence: 99%

“…The interpolated bounce-back (IBB) method [6] is often used to simulate flows around complex geometries at rest owing to its easy implementation. For example, the broadband sound generated from turbulent flow over an isolated airfoil was successfully predicted using the IBB method [7]. However, in cases involving moving boundaries such as fans, the IBB method suffers from unphysical pressure oscillations when the fluid and solid regions are switched [8].…”

Section: Introductionmentioning

confidence: 99%

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Aeroacoustic simulation of broadband sound generated from a cross-flow fan using immersed boundary-lattice Boltzmann method

Kusano

Furukawa

Sakoda

et al. 2022

J. Phys.: Conf. Ser.

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In this study, we investigated the capability of the immersed boundary-lattice Boltzmann method (IB-LBM) in simulating the broadband sound generated from a cross-flow fan. The present method is based on the lattice Boltzmann equation with the D3Q27 particle velocity model, and the cascaded collision operator was used to stably simulate high-Reynolds-number flows. Furthermore, the direct-forcing approach was used to consider rotating blades in the regular lattice. To capture turbulence eddies in the rotor, we used a high-resolution grid that contained approximately 340 million nodes. The simulation successfully captured the fundamental flow features of the cross-flow fan such as the eccentric vortex, and the simulation results were consistent with the experimental results in terms of the time-averaged velocity distribution at the outlet of the fan. In addition, by resolving turbulent eddies in the impeller, the simulation successfully predicted the broadband sound spectrum in the frequency range of 2 kHz or less.

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Section: Boundary Conditionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Aeroacoustic simulation of broadband sound generated from a cross-flow fan using immersed boundary-lattice Boltzmann method

Kusano

Furukawa

Sakoda

et al. 2022

J. Phys.: Conf. Ser.

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show abstract

“…Recently, the rapidly developing lattice Boltzmann method (LBM) 14,15 is a new method for aeroacoustic simulation 16–21 . Based on the molecular dynamics theory, LBM abstracts the fluid into a large number of microscopic particles, which migrate and collide on discrete lattices according to simple motion rules, and obtains the macroscopic motion characteristics of the fluid by counting the particles.…”

Section: Introductionmentioning

confidence: 99%

Acoustic multipole source–simplified lattice Boltzmann method for simulating acoustic propagation problems

Chen

Cao

Liu

et al. 2023

Numerical Methods in Fluids

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Combining the advantages of the acoustic multipole source (AMS) method and the simplified lattice Boltzmann method (SLBM), a method called AMS-SLBM is proposed for simulating the propagation of acoustic multipole sources in fluids. A particle source term is introduced to the right-hand side of the lattice Boltzmann equation using the AMS method, and the macroscopic equations with source terms are derived via the Chapman-Enskog expansion analysis. Employing the fractional step technique, the solving process of the macroscopic equations can be divided into three steps: the predictor, corrector, and supplement steps. In the predictor and corrector steps, macroscopic equations without source terms are solved by SLBM, and in the supplement step, the time advancement of the source terms is solved using the finite difference method.AMS-SLBM uses SLBM to simulate the propagation of sound waves by directly evolving the macroscopic variables, which evades the evolution and storage of the distribution function, and the computational process is simpler and memory can be reduced compared to the standard LBM. Moreover, since the acoustic source term is introduced to the right-hand side of the lattice Boltzmann equation by the AMS method, AMS-SLBM avoids the disadvantage that the traditional forced equilibrium distribution function method will interfere and cover the original flow field during the calculations. Several cases including the propagation of a plane wave, a Gaussian pulse and acoustic monopole, dipole, and quadrupole sources are simulated to validate the robustness and accuracy of the present method. The results show that AMS-SLBM can well simulate acoustic multipole sources propagation, and it affords second-order accuracy.

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“…The LBM has another feature that its scheme is lowdissipative enough to capture weak acoustic waves in low Mach number flows without any special treatment. In fact, the potential of LBM in application to aeroacoustic computations for low Mach number flows has been reported [8][9][10]. Moreover, the LBM begins to be actually applied to the simulation of low speed fans [11][12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Lattice Boltzmann simulation of flow and sound fields around an axial flow fan

Okuyama

Yamada

2022

J. Phys.: Conf. Ser.

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In this study, not only the flow field but the aerodynamic sound field around the axial flow fan were directly simulated using the lattice Boltzmann method (LBM). To validate the LBM results obtained in this study, they were compared with the experimental results in terms of the pressure rise performance characteristics. In order to investigate the change in the flow and sound fields due to different operating points, calculations were conducted at two operating points; one is the low flow rate point where the fan is stalled and the other is the high flow rate point where the flow field in the fan is sound. In the comparison of the performance characteristics, the calculation results showed good agreement with the experimental results, and the flow fields were well reproduced with high accuracy. The analysis in terms of the vortical flow structures and the relative velocity distributions showed that the tip vortex was generated by the pressure difference between both sides of the fan blade at the high flow rate point while at the low flow rate point the flow field near the fan tip was covered with the low velocity region and the leading edge separation occurred on the tip side of the fan blade. Therefore, it was confirmed from the flow field as well as the performance that the fan blade was stalled with the blade loading lost at the low flow rate point. Large pressure fluctuations on the fan blade surface were caused by the interaction with the tip vortex from the adjacent blade at the high flow rate point and the occurrence of leading edge separation at the low flow rate point. With regard to the comparison of the far field sound spectrum, the calculation results for both two flow rate points were in good agreement with the experimental results in a low frequency range, and the aerodynamic sounds generated from the fan were predicted well with the LBM simulation.

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Aeroacoustic simulation of broadband sound generated from low-Mach-number flows using a lattice Boltzmann method

Cited by 25 publications

References 39 publications

Aeroacoustic simulation of broadband sound generated from a cross-flow fan using immersed boundary-lattice Boltzmann method

Aeroacoustic simulation of broadband sound generated from a cross-flow fan using immersed boundary-lattice Boltzmann method

Acoustic multipole source–simplified lattice Boltzmann method for simulating acoustic propagation problems

Lattice Boltzmann simulation of flow and sound fields around an axial flow fan

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