COMSOL Multiphysics 4.4 [HOT]
Watch the release highlights video to find out what multiphysics modeling news COMSOL 4.4 brings you.With this version of COMSOL Multiphysics, we present you with a brand new user interface (UI) to redefine your modeling process, streamline your workflow, and enhance your modeling experience. The Windows UI of the COMSOL Desktop includes a ribbon for easier access to your modeling tools and a clearer view of your simulation workflow. A new Mixer Module has also been added to the product suite as an add-on to the CFD Module, and new functionality has been added to the Electrical, Mechanical, Fluid, Chemical, Multipurpose, and Interfacing products.After viewing the video, explore the complete details of COMSOL 4.4 on theRelease Highlights page.
COMSOL Multiphysics 4.4
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A model of a heating circuit was developed using COMSOL Multiphysics, the AC/DC Module, the Heat Transfer Module, and the Structural Mechanics Module. Results show the DC-induced Joule heating, heat transfer, and structural mechanics analysis of the thin resistive layer on a solid glass plate. When multiphysics phenomena such as thermal expansion is added to a model, the coupled physics is defined under the Multiphysics node in the Model Tree.
The new version offers a new ribbon design user interface that groups commands and displays them as needed, making it easier for users to find and use the tools available and get work done faster. Commands are grouped and ordered according to the main modeling tasks, which are themselves grouped under dedicated tabs for definitions, geometry, physics, mesh, study, and results. The COMSOL Desktop brings several additional workflow improvements, such as a one-click select feature that enables faster selections in the graphics window. Using this feature, users can now hover over a boundary or domain to highlight it, and then select it with a single click. Another noteworthy feature is the new auto-complete search function, which allows you to quickly find the postprocessing variables you need among the many that are created when working with multiphysics models.
A completely new Multiphysics node is now available in the model tree, enabling streamlined setup of multiphysics models. It allows users to easily expand upon combinations of single-physics interfaces by choosing from a list of relevant multiphysics couplings. The Multiphysics node provides the user with a comprehensive overview of the available couplings in the model so they can then control how to account for multiphysics phenomena by deciding how the physics included in your simulation interact with one another.
A ribbon design has been introduced to the COMSOL Desktop environment, when run on Windows platforms, to provide easier navigation and an enhanced user experience. By grouping commands and displaying them as needed, the ribbon makes it easier to find and use the tools available to let you get your work done faster. Commands are grouped and ordered according to the main modeling tasks, which are themselves grouped under dedicated tabs for definitions, geometry, physics, mesh, study, and results. The COMSOL Desktop brings several additional workflow improvements, such as a one-click select feature that enables faster selections in the graphics window. Using this feature, users can now hover over a boundary or domain to highlight it, and then select it with a single click. Another noteworthy feature is the new auto-complete search function, which allows you to quickly find the postprocessing variables you need among the many that are created when working with multiphysics models.
About COMSOLCOMSOL provides simulation software for product design and research to technical enterprises, research labs, and universities through 18 offices and a distributor network throughout the world. Its flagship product, COMSOL Multiphysics, is a software environment for modeling and simulating any physics-based system. A particular strength is its ability to account for coupled or multiphysics phenomena. Add-on products expand the simulation platform for electrical, mechanical, fluid flow, and chemical applications. Interfacing tools enable the integration of COMSOL Multiphysics simulation with all major technical computing and CAD tools on the CAE market.
The optical properties of metallic nanoparticles are well known,but the study of their thermal behavior is in its infancy. However the localheating of surrounding medium, induced by illuminated nanostructures, opensthe way to new sensors and devices. Consequently the accurate calculation ofthe electromagnetically induced heating of nanostructures is of interest. Theproposed multiphysics problem cannot be directly solved with the classicalrefinement method of Comsol Multiphysics and a 3D adaptive remeshing processbased on an a posteriori error estimator is used. In this paper theefficiency of three remeshing strategies for solving the multiphysics problemis compared. The first strategy uses independent remeshing for each physicalquantity to reach a given accuracy. The second strategy only controls theaccuracy on temperature. The third strategy uses a linear combination of thetwo normalized targets (the electric field intensity and the temperature).The analysis of the performance of each strategy is based on the convergenceof the remeshing process in terms of number of elements. The efficiency ofeach strategy is also characterized by the number of computation iterations,the number of elements, the CPU time, and the RAM required to achieve a giventarget accuracy.
In the following, we present the partial derivative equationsassociated with the multiphysics coupled problem. The interaction betweenlight and matter is governed by the Helmholtz equation derived from theMaxwell equations . The thermic problem is governed by the stationaryheat equation . The term of coupling between the electromagnetic andthermal problems is proportional to the square of the electric field insidethe metal [[parallel]E[parallel].sup.2]. Let us consider both mediasuccessively:
3.1. The Adaptive Remeshing Process. The finite element method isused to solve multiphysics problems in complex geometries . It is basedon the subdivision of the computational domain into elements, constitutingthe mesh. The accuracy of the solution depends on both the shape and thequality of the meshing of the domain. To reach a given accuracy of thesolution, a remeshing loop increases the number of elements in regions of[OMEGA] where the physical solution exhibits high gradients. At the sametime, the density of elements decreases in regions of slight variations ofthe solution. Nevertheless the total number of elements is always increasingfrom a step of remeshing to the next one, the minimum size of elements beingfixed to capture the variations of the solution. For example, inelectromagnetism, the minimum size of elements must be smaller than afraction of the wavelength. However the calculation on a heavier meshingrequires more memory and more computational time. Hence, the number ofremeshing steps required to reach a given accuracy is a critical parameter.Therefore the stop criterion for the remeshing loop is the stability of thenumber of elements: the calculation stops when the relative evolution [delta]of the number of elements [N.sub.i] from a step i to the next one is notgreater than 10%:
On the other side, if the computation of temperature must berepeated for the optimization of structures  or in an inverse problem, the computational time is critical. The cumulative time of computationis linked to the number of steps to reach the convergence criterion. Indeedit is typically about 11 hours for [A.sub.1], 2 hours for [A.sub.2], and 3hours for [A.sub.3]. Consequently, in case of massive use of the multiphysicsmodel, strategy [A.sub.2] could be the best candidate, even if the accuracyon the temperature is slightly relaxed. 350c69d7ab