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Burlington, MA, October 2000The real world is three-dimensional. Therefore, if a software package is to let users model any problem in science or engineering, it must offer 3-D capabilities. In addition, users demand quick, easy access to these features. The newest release of FEMLAB, Version 2.0, takes an enormous leap in functionality to reach this goalit now handles virtually any model a scientist or engineer can describe with partial differential equations (PDEs), in any dimension. These users can create and analyze models in full 3-D, and by employing the software's dynamic solvers they can even augment their analyses with the added dimension of time.
Furthermore, COMSOL is particularly proud of the upgrade's significantly enhanced graphical user interface. It adds tools that make 3-D multiphysics modeling easier than with any other software of its type. This interface, combined with FEMLAB 2.0's underlying solvers and multidimensional visualization tools, allow users to create model geometries and solve them on desktop machines in a fraction of the time they would need with other tools. Thanks to this major upgrade, they can now tackle tasks that just a few years ago would have required at least a powerful workstation if not a mainframe.
This functionality integrates tightly with the package's outstanding multiphysics capability, whereby users can solve a problem while employing PDEs from multiple branches of physics, and the software solves them all simultaneously and automatically without any user intervention. For instance, an electromagnetics problem will generally involve heat flow due to the currents running through various components, and that heat in turn could have an effect on the physical structure of the device or subsystem under analysis. FEMLAB handles all these aspects simultaneously and with ease, and now in three dimensions. Users have never had this amount of analysis power so handy and easy to use.
"Obviously, Version 2.0 allows our users to model problems that they could never dream of tackling before," comments Lars Langemyr, COMSOL's Vice President of R&D. What many people might not appreciate, though, is that this release also takes a considerable burden off people who have been trying to use available 2-D packages to tackle some of the more complex real-world applications. Certainly, 2-D multiphysics modeling software can prove quite useful for certain classes of problems. Further, users are able to make appropriate assumptions and simplifications could also do a reasonable job of approximating a 3-D problem with existing packages. But making these assumptions correctly and intelligently sometimes takes considerable knowledge, skill and experience. For instance, users might have to ask themselves, ´Where in the model should I take a 2-D cross-section? How do I handle boundary conditions?´
"With the release of FEMLAB 2.0, users no longer need worry about such issues," adds Langemyr, "because they can create a full 3-D model in a fraction of the time it would take them to make intelligent decisions about the simplifications and assumptions involved in setting up a 2-D model."
1. Draw the geometryThe first step in a modeling session is to describe the physical system with the package's built-in CAD tools. Although the software can work with 3-D objects, the PC's screen remains a 2-D display. Thus users build and modify problem geometries in 2-D work planes that the software afterwards joins into composite 3-D objects. It's thus as easy to draw 3-D objects as it has always been to draw a 2-D object.
To ease the development of geometries, FEMLAB 2.0 introduces a new class of 3-D primitive objects including blocks, spheres, ellipsoids, cones, and cylinders. In addition, special commands and functions such as Extrude, Revolve, and Embed make it a breeze to build 3-D objects from their 2-D counterparts. Yet other commands allow the software to take a 3-D solid and coerce it to a 3-D face object or vice versa.
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A toolbar dedicated to Draw mode makes it easier than ever to create and manipulate 3-D geometries. |
For users who wish to define or manipulate certain subdomains of a 3-D object, FEMLAB features a new array of interface capabilities and toolbars. They make it easier to select objects or subdomains in 3-D than with any other multiphysics package on the market, some of which require users to traverse deep into a menu tree for a simple operation. With FEMLAB, users can take the mouse and interactively select one or more faces, edges, or vertices. They can additionally highlight any combination of them, select all adjacent objects or cycle through them with a mouse click.
In creating a complex 3-D object it's not unusual to want to change how various objects appear or modify the viewpoint. For this purpose, FEMLAB allows users to suppress the display of geometry objects, boundaries or subdomains. They can also view a model from a different perspective by orbiting, panning, zooming or dollying the viewpoint.
2. Solve the modelAs before, users interact with modal dialog boxes to define the properties and characteristics of the solids they've drawn. Then a click on a button in the graphical user interface instructs FEMLAB to create the mesh and solve the problem. The package's new 3-D Delaunay-based mesh generator either runs with default settings or allows the user to control mesh size explicitly, either globally or selectively by subdomain, face, edge, or vertex.
Now the solvers come into play, and this upgrade's vastly improved iterative solvers consume less memory and therefore can handle larger models with more tetrahedrons in the mesh, thereby leading to higher accuracy in the results. Specifically, the package handles between 5x and 10x more mesh elements within the same amount of PC memory compared to software not using iterative solvers.
Note also that the package supplies state-of-the-art iterative solvers based on sophisticated algorithms and preconditioners that model two general types of problems:
and they all operate in any number of dimensions. The package can select a default it deems most appropriate to a given problem or users can specify which solver it should employ.
3. Visualization and post-processing of resultsIt's much easier to understand a system or analyze its performance if you can visualize various properties of the solution for different parameter values. Here FEMLAB 2.0 adds yet more functions to its already considerable array of existing visualization options.
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When you enter FEMLAB 2.0's Plot mode, a dedicated toolbar appears in the graphical user interface. With a click of a button you can perform sophisticated visual analyses. |
The click of a button can, for instance, call up a color-coded slice plot, an isosurface plot, a tube plot or a 3-D plot with cones or arrows. As before, the software can automatically create an animation that displays frames of a movie to illustrate dynamic effects.
It's also important to note that the mesh generator and solvers all employ MATLAB as their computational engine. Thus, as before, users can create a model exclusively with the graphical user interface, yet later export it as a series of command-line functions. In that way they can create instant documentation as well as access all of the sophisticated power of MATLAB to meet even the most demanding post-processing requirements.
It's important to note, though, that FEMLAB 2.0 also considerably improves the results for models that users could handle in 2-D. Briefly examine the case of an electrostatic precipator, which cleans particulates from dust-laden air. It consists of electrodes situated between parallel plates. The electrode is often helix shaped, making the precipator's geometry inherently 3-D. However, a 2-D model of the system can give vital qualitative information that in turn allows an engineer to build a simplified 3-D model that focuses on the most critical parts of the design.
COMSOL Inc is the US subsidiary of COMSOL AB, with headquarters in Stockholm, Sweden. The privately held firm was initially founded in 1986 by Svante Littmarck and Farhad Saeidi as a software distributor specializing in products from The MathWorks Inc (Natick, MA). In 1995 the principles started writing and distributing specialized add-ons for MATLAB, chief among them the PDE Toolbox. Most recently the company introduced FEMLAB, a MATLAB-based tool for the graphical modeling of complex problems built around partial differential equations.
"I was impressed with how smoothly the program operated from start to finish."
"The flexibility and generality of FEMLAB is unique, and it has allowed us to solve problems that were almost impossible or extremely time-consuming to solve with other packages."
"Without this package we'd have to purchase dedicated programs for each task and struggle to get them to work together"
"I can't live without it!"
Making it even easier to develop applications, FEMLAB bundles a Model Library that shows ready-to-run examples for common situations in multiple application areas. Thus users aren't required to have in-depth knowledge of mathematics or numerical analysis. In fact, they can build many models by means of the physical quantities involved rather than by writing the equations that describe them. Examining these models is also an excellent way of learning how to exploit the full power of FEMLAB within the various application areas.