Boundary Element Method for Acoustics and Electromagnetics Comes to COMSOL
Shawn Wasserman posted on December 14, 2017 | | 4815 views
COMSOL has sped up many of its solvers, enabling engineers to write up their reports faster.

COMSOL has sped up many of its solvers, enabling engineers to write up their reports faster.

Many computer-aided engineering (CAE) companies have been focusing on improving their user interfaces (UIs), solver speeds and functionality to ensure that engineers get their simulations faster.

The aim is to move away from those simulations that take the night, weekend or, heaven forbid, week to converge. Because if they don’t converge, you have problems.

With its latest release, COMSOL 5.3a, COMSOL has been busy focusing on the usability and speed of its core simulation software, with one solver improving its computational time by 40 percent.

Though it hasn’t been long since its spring release, COMSOL has not only sped up its platform, it has also added new electromagnetics, acoustics and plasma simulation techniques. The release also includes new hybrid boundary element method (BEM) compatibilities. And to cap it off, the software will greatly improve the workflow for chemical engineering users.

Solver Boosts Available in COMSOL 5.3a

COMSOL reports that its series of solvers has received an impressive speed boost since the 5.3 release. First, computational fluid dynamics (CFD) experts will be excited to see that the biggest improvement comes from the algebraic multigrid (AMG) solver.

“This is an iterative linear solver that can be used for a number of different applications—perhaps the most important is CFD,” confirmed Bjorn Sjodin, VP of Product Management, COMSOL. “Since the last release, we have seen up to 40 percent performance improvements for larger problems. And the larger the problem, the more significant the improvement.”

As for the geometric multigrid (GMG) solver, Sjodin explains that it has seen a performance boost of 20 percent for larger models.

So, what about users working with nonlinear problems? Here Sjodin notes that users can choose between a direct linear solver or an iterative linear solver. CAE specialists working with a direct linear solver should expect to see a 30 percent performance improvement for large models. This performance improvement comes from COMSOL now storing the information about the reordering of the matrices. This information is then reused between the nonlinear iterations, which leads to the improved solver efficiency.

Model Creation Improvements in COMSOL 5.3a

Figure 1. Comparison of transmission loss results from an automotive muffler using finite element analysis (blue) and a model reduced using modal analysis with 20 eigenmodes. (Image courtesy of COMSOL.)

Figure 1. Comparison of transmission loss results from an automotive muffler using finite element analysis (blue) and a model reduced using modal analysis with 20 eigenmodes. (Image courtesy of COMSOL.)

COMSOL 5.3a also comes with a handful of UI and functionality tweaks that are designed to improve preprocessing and model setup.

For example, users are now able to employ a user-defined function to govern the value of a parameter. If you define an interpolation function and parameterize the geometry, for example, you can then control the geometry based on that function.

“This would previously cause an error message in earlier versions,” noted Sjodin. “You can also access user-defined functions in a parametric sweep.

Engineers will also have a new way to reduce their models using modal analysis and asymptotic waveform evaluation (AWE). Using these tools, engineers can simplify their models without sacrificing accuracy. These simplified models are well suited for the faster compute cycles of systems simulations. This is why the tools are ideal for exporting with COMSOL’s LiveLink for MATLAB. However, these models can also be exported as a file if needed.

As shown in Figure 1, COMSOL has reduced the order of the transmission loss from an automotive muffler finite element (FE) analysis. The reduction was achieved using a 20 eigenvalue modal analysis. The frequency sweep chart shows that the results of both models are quite similar until high frequencies are reached.

Figure 2. Model Methods are now available in the model tree instead of in the developer tab. A similar change has been made with the Moving Mesh function, which is now in the model tree by default. (Image courtesy of COMSOL.)

Figure 2. Model Methods are now available in the model tree instead of in the developer tab. A similar change has been made with the Moving Mesh function, which is now in the model tree by default. (Image courtesy of COMSOL.)

One change to the COMSOL UI that should help with model creation is the move of the Model Methods function into the model tree. Previously, these functions were only available in the developer tab.

Model Methods are used to call COMSOL’s application programming interface (API). The API is a coding system that engineers can use to get COMSOL to perform certain tasks that would otherwise be difficult or impossible to perform with the UI. For instance, an API could call for data from third-party software. Previously, these Model Methods didn’t include input arguments, but now this functionality is available in 5.3a.

Another UI change to COMSOL is that Moving Mesh functionality is now located in a new position in the model tree, under “Definitions.” This function is still available as a separate physics interface; however, this move will make the function more accessible to various multiphysics models that require a Moving Mesh.

Other Model Methods creation improvements include the addition of:

  • 150 new materials and 1,300 new material properties to the library
  • 60 microwave and circuit substrates from Rogers Corporation to the Radiofrequency module 

Chemical Engineering and Heat Transfer Additions to COMSOL

Figure 3. The new thermodynamic property libraries and moisture flow multiphysics coupling can help engineers simulate the moisture coming from this coffee cup. (Image courtesy of COMSOL.)

Figure 3. The new thermodynamic property libraries and moisture flow multiphysics coupling can help engineers simulate the moisture coming from this coffee cup. (Image courtesy of COMSOL.)

Chemical engineers will greatly appreciate some new thermodynamic property libraries that have been added to COMSOL 5.3a.

These libraries include thermodynamic data such as:

  • Transport properties
  • Heat of formation
  • Heat of evaporation
  • Heat of mixing

These values will be invaluable to those simulating chemical reactions and equilibria. Traditionally, engineers needed to look up these numbers and input them into COMSOL. Now, this data is all built in, speeding up the workflow considerably.

Another interesting chemical engineering and heat transfer addition to COMSOL is the moisture flow multiphysics coupling model. Using this tool, one could simulate the moisture coming off a coffee cup as shown in Figure 3, or assess the safety of electronics in a moist environment, or even check a leaking HVAC system.

Other heat transfer and chemical engineering improvements to COMSOL include:

  • New realizable k-ε model for turbulence simulations
  • Temperature distribution inlet streams
  • New Beer-Lambert law interface for light and laser absorption in weakly absorbing media

Hybrid BEM for Electromagnetics and Acoustics Added to COMSOL 5.3a

Figure 4. Magnetic field at 1 km from a submarine. This simulation is calculated using BEM. (Image courtesy of COMSOL.)

Figure 4. Magnetic field at 1 km from a submarine. This simulation is calculated using BEM. (Image courtesy of COMSOL.)

COMSOL has added quite a lot of BEM compatibility into its 5.3a release. Previously, BEM was compatible with electrostatics, electrodeposition and corrosion. Now, BEM has been expanded to work with magnetostatics and acoustics simulations.

“BEM for magnetostatics is a good complement to the FE method,” said Sjodin. “BEM allows you to just mesh the surface of a model in order to evaluate the magnetic field anywhere outside of that surface. So, even if you just mesh the surface, you can evaluate the magnetostatics in the volume in the near, medium and far field with the same amount of analysis time.”

Sjodin notes that this can be a great tool to help assess where you might need to add magnetic field sensors. With the tool, you will know which areas are supposed to have low and high magnetic fields. As a result, you can place sensors in areas of low interference.

Previously, engineers could use BEM in COMSOL to assess a magnetic field on which they had to mesh their targeted domain and run an Finite Element Method (FEM) analysis. If that field was enlarged or shrunk, as design criteria changed, then they would need to calculate it all over again. With BEM, this process is simplified.

“Once you compute your field outside your objects with BEM, you can compute [the field] everywhere as [BEM analysis goes] off to infinity,” said Sjodin. “The behavior is already computed, so you can post-process anywhere outside your model without recalculating. With FE, you would have to expand your domain and recompute your model.”

Sjodin explains that the BEM model can also be linked to an FEA model in a hybrid approach. This can be useful if you are modeling something anisotropic or nonlinear that would require FEA, and then assess how that model would affect the far field, which would be best assessed using BEM.

Figure 5. Hybrid FEA and BEM simulation to assess a speaker system. (Image courtesy of COMSOL.)

Figure 5. Hybrid FEA and BEM simulation to assess a speaker system. (Image courtesy of COMSOL.)

Figure 6. Combining BEM, FEA and ray acoustics allows engineers to simulate a large range of audio setups. (Image courtesy of COMSOL.)

Figure 6. Combining BEM, FEA and ray acoustics allows engineers to simulate a large range of audio setups. (Image courtesy of COMSOL.)

A similar scenario to the hybrid FEA/BEM for electromagnetics can also now be applied to acoustics.

As an example, take a speaker. In this scenario, engineers can combine a structurally vibrating domain, which was modeled using a shell or finite element, with BEM to assess the speaker’s far-field acoustics.

This is all possible, thanks to the added BEM acoustics functionality in 5.3a.

“Inside the speaker, we would use FEA for the pressure simulation as FE is best in enclosed spaces that are affected by resonance,” noted Sjodin. “But BEM is best for unbound domains where objects are separated by large distances.”

So, what future BEM compatibility should engineers be looking out for in COMSOL?

Well, Sjodin hints that in future releases, DC currents and heat transfer might be some great options.

Other electromagnetic improvements to COMSOL 5.3a include:

  • Soft-magnetic material model to assess demagnetization
  • Study type for adaptive frequency sweeps using an asymptotic wave form evaluations solver

Another acoustics improvements to COMSOL 5.3a is compute impulse response for ray acoustics.

COMSOL 5.3a Adds Capacitively Coupled Plasmas

Figure 7. Simulation of the period-averaged electric potential in an asymmetric CCP reactor. The reactor’s asymmetry creates a negative DC self-bias at the powered electrode. (Image courtesy of COMSOL.)

Figure 7. Simulation of the period-averaged electric potential in an asymmetric CCP reactor. The reactor’s asymmetry creates a negative DC self-bias at the powered electrode. (Image courtesy of COMSOL.)

COMSOL’s 5.3a release has a few improvements that will catch the attention of engineers working to design a capacitively coupled plasma (CCP) reactor.

Traditionally, simulating these industrial plasma sources was tricky. In fact, Sjodin suggests that these simulations couldn’t be performed natively in COMSOL at all.

“If you did manage to set one up, you were still looking at solution times of weeks for a 2D model,” said Sjodin.

In the 5.3a release, COMSOL has created a model for CCP that is based on a nonlinear time periodic function.

“Now we are looking at solution times of hours, so orders of magnitude faster. But for most users, it’s a matter of being able to simulate CCPs at all,” Sjodin added.

For more plasma simulations from COMSOL, watch this webinar.

This article is just scratching the surface of what you can expect in the latest COMSOL update. We didn’t even get to any structural, COMSOL Server of Application Builder News. There is even some interesting shape memory alloy news for those using these revolutionary materials.

To learn more about COMSOL 5.3a, watch the webinar here.

COMSOL has sponsored this post. They have no editorial input to this post. Unless otherwise stated, all opinions are mine. —Shawn Wasserman

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