{"id":7878,"date":"2019-10-04T13:16:40","date_gmt":"2019-10-04T17:16:40","guid":{"rendered":"https:\/\/blogs.sw.siemens.com\/simcenter\/?p=7878"},"modified":"2026-03-26T06:07:43","modified_gmt":"2026-03-26T10:07:43","slug":"3-validated-aero-vibro-acoustic-scenarios-to-solve-flow-induced-noise","status":"publish","type":"post","link":"https:\/\/blogs.sw.siemens.com\/simcenter\/3-validated-aero-vibro-acoustic-scenarios-to-solve-flow-induced-noise\/","title":{"rendered":"3 aero-(vibro)-acoustic scenarios to solve flow-induced noise"},"content":{"rendered":"\n

Inside the car\u2019s cabin, and especially for a hybrid or an electric vehicle, the overall noise level is primarily dominated by HVAC, cooling and wind noise. These are usually simulated using FEM models. Yet, there are FE models and FEM models. What is meant with \u2018lean\u2019 FEM models? And how can you benefit from these lean FE models to facilitate the prediction of flow-induced noise? <\/p>\n\n\n\n

The supremacy of lean FEM models to solve flow-induced noise<\/h2>\n\n\n\n

Finite Element Model Adaptive Order, or FEMAO, does the trick. Adaptive models contain the right number of Degrees of Freedom (DOFs) at whichever frequency of interest. They offer the same accuracy and level of detail, but much faster than standard FEM simulations.<\/p>\n\n\n\n

How? Well, unlike standard FEM simulations which need to use very small FE elements to capture pressure fields at higher frequencies. FEMAO uses a coarse mesh to represent an acoustic domain, while the solver automatically adapts the order of the polynomials that were used to describe the pressure field within the FEM elements. Hence, the mesh is not refined with frequency. Yet the number of shape functions and their polynomial order is increased per element and per frequency. Moreover it is fully automatic, based on accuracy criteria. 1-0 for lean FEM models!<\/p>\n\n\n\n

OK. Back to solving aero-acoustic and aero-vibro-acoustic source\ngeneration and propagation. Typically, this simulation solution supports three\ntypes of scenarios. These are described and demonstrated during the free\nwebinar: 3\nvalidated aero-(vibro)-acoustic scenarios to predict noise levels<\/a>. We give\nyou a glimpse hereunder.<\/p>\n\n\n\n

1. Wind noise<\/h2>\n\n\n\n

Wind noise originating from a flow around a side mirror and\nA-pillars is emitted towards the car interior from side-window vibrations due\nexternal fluid loading. Logically, we need to compute acoustic pressure levels\nat driver’s ear. <\/p>\n\n\n\n

To solve wind noise, we start with accurately analyzing the naked\nexternal aerodynamic loading on the CFD mesh boundaries. Next, we prepare wind\nloads for the vibro-acoustic model via advanced mapping. Eventually, we compute\nefficient FEM vibro-acoustic simulations<\/a> using single coarse physical mesh for\nall frequencies of interest of the\nside-window and car interior using wind loads.<\/p>\n\n\n\n

\"\"
Example of how to solve aero-vibro-acoustic source generation and propagation at Hyundai Motor Company<\/em> <\/figcaption><\/figure>\n\n\n\n

2. HVAC noise<\/h2>\n\n\n\n

As there is no masking noise from an internal combustion\nengine, flow induced acoustic sources on static components, such as HVAC noise\nis more prominent in electric and hybrid electric vehicles. There are various\nalternatives to handle the flow induced noise from duct components; with\nSimcenter STAR-CCM+ only, or by coupling Simcenter 3D with Simcenter STAR-CCM+\nsoftware. Both provide accurate results with different assumptions in\nfree-field, while the hybrid solution also provides the acoustic response in presence\nof installation effects (including absorbing and reflective surfaces in the\ncabin).<\/p>\n\n\n\n

\"\"
Academic example of noise generated by a flap in a simplified HVAC duct<\/em> <\/figcaption><\/figure>\n\n\n\n

3. Fan noise<\/h2>\n\n\n\n

Depending on the user\u2019s application, flow induced acoustic sources on rotating bladed components that generate fan noise, is addressed by either deploying the workflow with Simcenter STAR-CCM+ or by combining Simcenter STAR-CCM+ and Simcenter 3D solutions. Both methods rely on transient CFD simulation<\/a> and provide the same results in free-field for tones and broadband levels (when there are no reflective or absorbing surfaces in the environment of the fan). In case you want to compute the acoustic propagation in presence of so-called installation effects such as walls, filters, heat exchangers, we couple both software solutions. <\/p>\n\n\n\n

\"\"
Academic example of noise generated by a flap in a simplified HVAC duct<\/em> <\/figcaption><\/figure>\n\n\n\n

Interested to hear more? Watch the on-demand webinar: 3 validated aero-(vibro)-acoustic scenarios to predict noise levels<\/a> and discover how to predict and address flow-induced noise at an early stage of the design cycle. <\/p> Korcan Kucukcoskun <\/cite><\/blockquote>\n\n\n\n

This aero-acoustic<\/a> modelling approach for flow-induced noise enables lean, surface pressure-based source creation for stationary or rotating surfaces. It requires minimized input data from CFD solution for source generation. Coupling the FEM structural solver with FEMAO acoustic solutions also allows to account for installation effects in sound propagation. <\/p>\n\n\n\n