COMSOL is a company that offers various multiphysics modelling and simulation solutions to a number of industries, including the automotive industry. Within the sphere of modelling, acoustics analysis is playing a major role in designing components and various features of a vehicle in order to enhance the overall driving experience. In conversation with Dr Mads J Herring Jensen, Technical Product Manager, Acoustics, COMSOL, we find out the typical areas where acoustics analysis is employed in design, along with its integration with other modelling areas.
INTERGRATION OF CFD IN ACOUSTICS
The integration of computational fluid dynamics (CFD) in acoustics for the automotive industry is used in several places. One of these is exhaust systems where there is a muffler that has specific acoustics characteristics. However, when a flow is introduced into the muffler, its acoustic characteristics are modified. Intake systems are another area in the automotive sphere where there is an interaction of CFD and acoustics, for which COMSOL offers solutions, said Dr Jensen.
He explained that until recently, muffler systems were modelled without any flow characteristics, but now companies are also solving the flow dynamics inside the muffler with CFD and then solving acoustics on top of it. One of COMSOL’s tools relating to full linearised navier-stokes equations has been improved to model the interaction of flow and acoustics, Dr Jensen noted.
Another topic of interest in the automotive industry is that of flow-induced noise, which is typically created by outside rear-view mirrors. But that area is one which the company is currently not focusing on, said Dr Jensen, adding that the company is aware of the interest from the automotive industry to address this topic, which may be the focus of future releases, after attaining more technical knowledge on the same.
AUTOMOTIVE ACOUSTIC SYSTEMS
Large suppliers of automotive components need to ensure that audio systems are an integrated part of the design of the vehicle, and require the sound output to be of high quality. This is a very good area for COMSOL because the company has multiphysics tools for transducer (large speakers), which integrate electrical systems, mechanical systems and acoustics. Additionally, there is the coupling of the transducer and where it is mounted on the car door, where the vibrations of the car door come into play. All this information can then help in assessing the best points of placing speakers and enhancing the audio quality inside the vehicle. This is a typical multiphysics application, where companies use COMSOL solutions to test and optimise their audio systems, said Dr Jensen.
Another area of use within the vehicle is in COMSOL’s solutions to create models of acoustics for interiors of the vehicle that contain various types of materials. These include different porous materials, as well as various woods or plastics. The company also offers built-in functionalities with varied levels of detail for these materials. This is especially important, since in order to get the desired sound staging inside the car, surfaces and materials need to be characterised correctly.
Dr Jensen said that COMSOL has recently released a new tutorial model of a full gearbox (with all vibro-acoustic details), from which the radiated sound of the gearbox can be calculated. This model helps in identifying specific frequencies of sound from the gearbox, and incorporates multi-body dynamics, gears, structural mechanics and acoustics. These models can help with design elements such as putting sound barriers between the engine and the cabin, as well as in enhancing the in-cabin experience.
COMSOL’s acoustic analysis tools are also used in automotive safety systems like parking sensors, Dr Jensen noted. He explained that parking sensors in cars are ultrasound transducers, which emit ultrasound signals that are used to record the time of flight, and then characterise the distance of an obstacle. Customers use COMSOL to model transducers, and then also model how the sound field reacts to different objects.
Customers in India have increasingly started to look at solutions like acoustics analysis in the development of new products and systems. It must be noted that the potential of what customers want to model is much bigger that what it was earlier, with the systems being more realistic, said Dr Jensen. Coupling of acoustics with other physics models are also said to be helping customers develop better systems. Earlier, customers used simulation software to identify the problems already present in a system. Nowadays, software is used to identify possible defects/issues while developing and designing a system, and optimise it before production. This leads to virtual prototyping, with most of the errors identified and ironed out before the system is built.
Dr Jensen said that COMSOL offers not only multiphysics modelling, but its software is also multi-method in nature. The software uses methods of infinite elements, finite elements, boundary elements, discontinuous Galerkin methods, ray tracing methods, and finite volumes, with the philosophy of everything being coupled together. This sometimes means that a tool would take a longer time to be developed, since the coupling feature would take up more development time. This is the also the case with the development of acoustic analysis tools, which are gaining prominence in the automotive industry in India for the development of various systems.
TEXT: Naveen Arul