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How to perform the Aeroacoustics analysis for Air flow in Pipe?

Hi Good Day!

I have an air blower model, and I want to perform an analysis to determine the sound levels at the inlet and outlet.

Before working on the actual case, I’d like to start with a simpler scenario — air flowing through a pipe.

Let’s consider a 1-meter pipe, where I know the mass flow rate at the outlet and assign the stagnation pressure at the inlet.

Using this example, could you guide me on how to set up the analysis in AcuSolve with SimLab? Also, is any co-simulation required for this, such as involving AcuSolve with OptiStruct or other tools?
Additionally, if there are any best practices or similar tutorials available for this type of analysis, I would greatly appreciate if you could share them.

Thanks & Regards,
Sivaprakash V.

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HyperMesh CFD

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Accepted answers

ydigit

We are talking about high end GPUs, like A100/H100 (with 80 GB GPU RAM, not CPU-RAM). Plus to get any realistic results (not just Color For Directors) you would need at least 4 of those GPU cards.

I doubt, given your hardware it would be possible to get anything realistic.

Altair does provide cloud options, to run such examples on high end GPUs.

Although the site does not mention uFX for free trial, please contact your Account Manager for detailed discussions on this topic.

Altair Unlimited - Request a Trial

ydigit

Plus uFX runs only on Linux.
Windows is currently not an option, due to CUDA restrictions on Windows for MPI (AFAIK).

All comments

ydigit

Hi,

ultraFluidX is the CFD solver for fan noise. See following for overview:

Webinar: Fan Acoustics using Altair ultraFluidX

Article: Reducing Fan Noise With Altair’s CFD Acoustics - AEM | Association of Equipment Manufacturers

Customer presentation: ATCx_2023_VALEO_Petr_Nekolny_nFX_Aero_Acoustic_Simulation.pdf

Note, you would need high end GPUs like A100 or H100, with Linux, to run a realistic simulation, due to high fidelity of such simulations.

Please contact your Account Manager, to plan a meeting with an Altair expert on the topic.

Sivaprakash_V

Hi,

Thank you for your response.

Unfortunately, we don’t have access to high-end GPUs on our Linux systems.

Is such hardware really necessary for running a simple simulation like airflow through a pipe without a fan?

Thanks & Regards,
sivaprakash v.

GabrielP

Hi @Sivaprakash_V ,

ultraFluidX solver is only working on Nvidia GPUs.

For a successful Aeroacoustics simulation, there are 2 sets of phenomena that need to be resolved properly:
1) Sound generation: for aeroacoustics we are speaking about flow-induced pressure disturbances that are due to either turbulent structures, flow impigements, vortice induced, strong shear layers, rotating devices pushing air against a static structures, cavity oscillations…. there are a full array of different flow mechanisms which are responsible for pressure disturbances generating sound waves. And you need to make sure that the simulation is capturing reliably these phenomena

2) the sound propagation. Once created, the pressure disturbance is generating a spherical wave travelling at the speed of sound. This wave will travel, reflect, refract on wall surfaces before reaching a listening surface or a microphone to extract noise level from. This requires to have a fine enough mesh to resolve the propagation of the smallest wavelength of interest.

Even if the case seems simple in geometry and flow, it needs to capture accurately the point 1 otherwise there are nothing to be propagated to the listeners and reversely if the propagation is not done properly, no sound wave will reach the listener. Unfortunately there are no shortcuts and simple aeroacoustic cases, and this is why I find it so interesting.

In summary, aeroacoustic simulation needs a careful and thoughtful setup not allowing for a lot of shortcuts, this is why we are using uFX which is allowing the adequate level of flow details, but it is only based on computational GPUs.

I hope you'll find this interesting and if you want to know more, please feel free to contact your Altair account manager to arrange a meeting.

All the best,
Gabriel

Sivaprakash_V

Hi Gabriel,

Thank you for your insightful reply.

Yes, we have access to a system equipped with a decent NVIDIA graphics card running Windows, along with 64 GB of RAM and 32 cores.

Would it be feasible to perform the analysis using this setup?

Additionally, as I’m completely new to this type of analysis, could you suggest where to begin from a beginner’s level? I’d also appreciate any recommendations for tutorials or books related to this analysis using Altair.

Thanks and regards,
Sivaprakash V.

ydigit

We are talking about high end GPUs, like A100/H100 (with 80 GB GPU RAM, not CPU-RAM). Plus to get any realistic results (not just Color For Directors) you would need at least 4 of those GPU cards.

I doubt, given your hardware it would be possible to get anything realistic.

Altair does provide cloud options, to run such examples on high end GPUs.

Although the site does not mention uFX for free trial, please contact your Account Manager for detailed discussions on this topic.

Altair Unlimited - Request a Trial

ydigit

Plus uFX runs only on Linux.
Windows is currently not an option, due to CUDA restrictions on Windows for MPI (AFAIK).