COMSOL Multiphysics^{®}
COMSOL Multiphysics^{®}
The Platform for Physics-Based Modeling and Simulation
- COMSOL Desktop^{®}: A mechanical simulation of a wrench computing the effective stress and deformation.
- COMSOL Desktop^{®}: A fluid flow and chemical transport simulation of a micromixer with fluid velocity field and species concentration.
- COMSOL Desktop^{®}: An electrical simulation of a pacemaker electrode with computed voltage and current distribution.
The COMSOL Desktop is a powerful integrated user interface environment designed for cross-disciplinary product development with a unified workflow for electrical, mechanical, fluid, and chemical applications.
Simulation Tool for Electrical, Mechanical, Fluid Flow, and Chemical applications
COMSOL Multiphysics^{®} is a general-purpose software platform, based on advanced numerical methods, for modeling and simulating physics-based problems. With COMSOL Multiphysics, you will be able to account for coupled or multiphysics phenomena. With more than 30 add-on products to choose from, you can further expand the simulation platform with dedicated physics interfaces and tools for electrical, mechanical, fluid flow, and chemical applications. Additional interfacing products connect your COMSOL Multiphysics simulations with technical computing, CAD, and ECAD software.
The COMSOL Desktop^{®} for Cross-Disciplinary Product Development
The COMSOL Desktop^{®} is a powerful integrated environment designed for cross-disciplinary product development with a unified workflow, regardless of the application area. The add-on modules blend in seamlessly with COMSOL Multiphysics, and the way you operate the software remains the same no matter which add-on products are engaged. The Model Tree in the Model Builder gives you a full overview of the model and access to all functionality – geometry, mesh, physics settings, boundary conditions, studies, solvers, postprocessing, and visualizations. With COMSOL Multiphysics you can easily extend conventional models for one type of physics into multiphysics models that solve coupled physics phenomena – simultaneously. What's more, accessing this power does not require in-depth knowledge of mathematics or numerical analysis.
User Interfaces for Modeling and Simulation
Back to TopPhysics and Equation-Based Modeling Interfaces
Using COMSOL Multiphysics provides you with a significant amount of physics modeling functionality, including multiphysics ability. By adding application-specific modules, the modeling power is increased with dedicated tools for electrical, mechanical, fluid flow, and chemical applications. COMSOL Multiphysics includes a set of core physics interfaces for common physics application areas such as structural analysis, laminar flow, pressure acoustics, transport of diluted species, electrostatics, electric currents, heat transfer, and Joule heating. These are simplified versions of a selected set of physics interfaces available in the add-on modules.
For arbitrary mathematics or physics simulations, where a preset physics option is not available, a set of physics interfaces are included for setting up simulations from first principles by defining the equations. Several partial differential equation (PDE) templates make it easy to model second-order linear or nonlinear systems of equations. By stacking several equations together, you can also model higher-order differential equations. These equation-based tools can further be combined with the preset physics of COMSOL Multiphysics or any of the add-on modules, allowing for fully-coupled and customized analyses. This dramatically reduces the need for writing user subroutines in order to customize equations, material properties, boundary conditions, or source terms. Also available is a set of templates for classical PDEs: Laplace's equation, Poisson's equation, the wave equation, the Helmholtz equation, the heat equation, and the convection-diffusion equation.
Coordinate Systems
Users enjoy the ability to define any number of local coordinate systems. There are shortcuts for common coordinate systems such as cylindrical, spherical, and Euler-angle based, and a method for automatic coordinate system creation makes it easy to define anisotropic material properties that follow curved geometric shapes. This curvilinear coordinates tool, included in COMSOL Multiphysics, can be applied for any type of physics, like anisotropic thermal conductivity in heat transfer, orthotropic materials for structural mechanics, and anisotropic media in electromagnetics, for example.
Model Couplings
The COMSOL Desktop^{®} allows you to work simultaneously in 3D, 2D, 1D, and 0D. So called Model Couplings can be used to map any quantity across spatial dimensions. For example, a 2D solution can be mapped to a 3D surface or extruded throughout a 3D volume. This functionality makes it easy to set up cross-dimensional simulations. Furthermore, systems of algebraic equations, ordinary differential equations (ODEs), or differential algebraic equations (DAEs) – referred to as 0D models – can be combined with spatially dependent 1D, 2D, and 3D models.
- Partial Differential Equations: An equation-based model of electrical signals in a heart, solving a system of transient nonlinear partial differential equations.
Moving Mesh with ALE
COMSOL Multiphysics includes advanced moving mesh functionality, based on the arbitrary Lagrangian-Eulerian (ALE) method, where you can define physics with respect to a moving frame of reference. This can be either a material frame or a spatial frame depending on what is relevant for the physics at hand. The technology is also included in some of the add-on modules, where moving meshes are coupled to other physics: fluid-structure interaction (Structural Mechanics Module and MEMS Module), corroding surfaces (Corrosion Module), electrodeposition (Electrodeposition Module), electromechanics (MEMS Module), and two-phase flow (Microfluidics Module). The ALE functionality included in COMSOL Multiphysics also makes it possible to perform custom-built simulations in cases where a built-in option is not available.
Meshing and Finite Element Types
Back to TopAutomatic and semi-automatic meshing tools are available in COMSOL Multiphysics, including free tetrahedral meshing and swept meshing. The default algorithm is automatic tetrahedral meshing for physics defined in solids, and a combination of tetrahedral and boundary-layer meshing for fluids. You can also take full control over the sequence of operations used for creating the mesh by defining a so-called mesh sequence. A mesh sequence allows for a mix of tetrahedral, prismatic, or hexahedral elements and can be made parametrically driven. In addition, when importing a mesh on one of the NASTRAN formats, pyramid elements are also supported. A mesh imported on the NASTRAN format can be subsequently partitioned on the domain, boundary, and edge levels by additional coordinate-based operations.
COMSOL's unique approach to multiphysics separates the geometric shape (in 3D: tet, prism, hex, pyramid) of the finite elements from the "finite element shape functions". This provides maximum flexibility, and each geometric shape supports first, second, third, and, in some cases, higher-order shape functions, corresponding to traditional linear, quadratic, or cubic finite elements respectively. Many types of physics utilize Lagrange finite elements, also know as isoparametric nodal-based finite elements. This includes heat transfer, structural mechanics, electrostatics, and more. For CFD, specialized elements and numerical stabilization schemes are also used. For vector-field electromagnetics, curved and higher-order curl elements, also known as edge or vector elements, are used.
Geometry Modeling
Back to TopCOMSOL Multiphysics provides 1D, 2D, and 3D geometry modeling tools with a COMSOL native geometry kernel. A number of primitive objects are available, as well as the capability of extruding general 2D geometry objects into 3D. Additionally, 2D objects can be revolved or swept along parametric curves. Boolean operations such as union, difference, and intersection are used to form more complicated shapes involving combinations of solids, surfaces, curves, and points. Free form modeling capabilities include parametric surfaces, parametric curves, and interpolation curves. All geometry operations are organized in a parametric sequence of operations in the Model Tree. For access to more advanced CAD functionality, there are the add-on CAD Import Module and the LiveLink^{™} products for CAD. These boost the geometry modeling capabilities by including the Parasolid^{®} geometry kernel, and they provide a range of CAD import/export formats as well as CAD interoperability with leading CAD systems. For a list of geometry modeling functionality and import/export formats, see the CAD Specifications page.
State-of-the-Art Numerical Methods
Back to TopCOMSOL Multiphysics assembles and solves models using state-of-the-art numerical analysis methods. Several different methods are used in the add-on modules, including finite element analysis, the finite volume method, the boundary element method, and particle tracing methods, but the emphasis of COMSOL Multiphysics is on the finite element method. Many types of finite elements are available, and fully coupled elements are automatically generated by the software at the time of solving. This patented method of generating finite elements "on-the-fly" is precisely what allows for unlimited multiphysics combinations – something that is unique to COMSOL Multiphysics.
The software runs the analysis together with adaptive meshing (if selected) and error control using a variety of numerical solvers: direct and iterative sparse matrix solvers, algebraic and geometric multigrid methods, as well as a range of preconditioners. Solver defaults are used that depend on the physics combinations. The user can view the solver settings and also manually configure low-level settings. When available, the solvers and other computationally intense algorithms of any COMSOL license make use of multicore computing. Cluster and cloud computing are enabled by the floating network license option. A set of solvers is organized in a higher-level Study; one Study can hold a sequence of solvers, such as for stationary, eigenfrequency, frequency-domain, and time-dependent analyses. The application-specific modules have additional solver options, such as those for pre-stressed or small-signal analysis, and combined frequency and time-domain analysis. Sensitivity analysis is included in COMSOL Multiphysics and a suite of optimization solvers is available in the add-on Optimization Module.
Parametric and Associative Models
Back to TopCOMSOL creates sequences to record all steps that create the geometry, mesh, studies and solver settings, visualization, and results presentation. You can therefore easily parameterize any part of the model, by simply changing a node in the Model Tree and re-running the sequences. The program remembers and reapplies all other information and data in the model. In addition, the connection between the geometry and the simulation settings is fully associative – a change in the geometry will automatically propagate changes throughout the model. If you prefer a command-driven environment, you can also run COMSOL Multiphysics in batch mode.
Variables, Expressions, and Look-up Tables
Back to TopCOMSOL Multiphysics comes with a built-in interpreter for mathematical expressions. Expressions can be assigned to variables for later use in material properties, boundary conditions, or sources. This means that most of the time you do not need to write code to adapt the software when there is a need for a custom expression. The coordinate variables x, y, and z can be used to define spatially varying quantities, for instance, distributed loads. In a similar way, lowercase t is reserved for time, and can be used in expressions to shape time-varying pulses for transient simulations.
A number of operators are available for smoothing, linearization, differentiation, and more. In addition to a set of built-in function templates, like Gaussian and rectangle pulses, you can define look-up table functions either directly in the COMSOL Desktop^{®} or read them from file. Inhomogeneous material properties can be represented by referencing a volumetric look-up table with properties as a function of spatial coordinates. As an alternative to numerical tables, you can use image data on a number of common image formats as a basis for an interpolation function. This can, for example, be used to map image pixel values to material property values. You can also combine mathematical expressions with function calls into composite expressions involving both types. For representing topographic geometry data, you can import digital elevation map (DEM) data and use it in combination with parametric surfaces.
APIs and the Physics Builder
Back to TopAlthough the COMSOL Desktop^{®} environment lends itself for easy and general customization, a number of different application programming interfaces (APIs) are available. The COMSOL^{®} API for use with Java^{®} comes included with COMSOL Multiphysics, and provides a programmatic way of driving the software through compiled object oriented code. LiveLink^{™} for MATLAB^{®} allows you to work with COMSOL Multiphysics in combination with the MATLAB^{®} technical computing language. Getting started with the COMSOL^{®} API for use with Java^{®} and LiveLink^{™} for MATLAB^{®} is quick, as you can save a model that has been set up in the COMSOL Desktop^{®} to the Java or MATLAB file formats, respectively.
The Physics Builder, which is included in COMSOL Multiphysics, allows you to create your own physics interfaces accessible from the COMSOL Desktop^{®} with the same look-and-feel as the built-in physics interfaces. In the case of the Physics Builder, no programming is needed as you work directly in the COMSOL Desktop^{®} from the Physics Builder Tree, defining new user interface components.
Exporting Results and Generating Reports
Back to TopResults can be exported to text files on the .txt, .dat, and .csv formats. With LiveLink^{™} for Excel^{®}, results can be exported to the Microsoft^{®} Excel^{®} .xlsx format. Images can be exported to several common image formats, while animations can be exported to Animated GIF, Adobe® Flash, or AVI. Get more details on export file formats.
Reports summarizing the entire simulation project can be exported to HTML (.htm,.html) or Microsoft® Word® (.doc) format. Three default report choices are available: Brief, Intermediate, or Complete. However, you can also choose to build customized reports from the different parts of the Model Tree.
Results Visualization and Postprocessing
Back to TopVisualization capabilities include surface, slice, isosurface, cut plane, arrow, and streamline plots, as well as many other plot types. Visualizations are not limited to built-in quantities, but can be expanded with composite physical quantities by typing mathematical expressions in the unknown field variables, as well as their derivatives. As a result, you can visualize just about any quantity of interest related to simulation results. A range of postprocessing tools are available for evaluation and integration. You can compute the max, min, average, and integrated values of any quantity or composite quantities, throughout volumes, on surfaces, along curved edges, and at points.
Verify and Optimize your Simulations
Back to TopCOMSOL Multiphysics is a flexible platform that allows users to model all relevant physical aspects of their designs. Expert users can dig deeper and use their knowledge to develop customized solutions, applicable to their unique circumstances. With this kind of all-inclusive modeling environment, COMSOL gives you the confidence to build the model you want with real-world precision.
Certain characteristics of COMSOL become apparent with use. Compatibility stands out among these. COMSOL requires that every type of simulation included in the package has the ability to be combined with any other. This strict requirement mirrors what happens in the real world. For instance, in nature, electricity is always accompanied by some thermal effect; the two are fully compatible. Enforcing compatibility guarantees consistent multiphysics models and the knowledge that you never have to worry about creating a disconnected model again.
Another noticeable trait of the COMSOL Desktop^{®} is adaptability. As your modeling needs change, so does the software. If you find yourself in need of including another physical effect, you just add it in. If one of the inputs to your model requires a mathematical formula, you can just enter it. Using tools like parameterized geometry, interactive meshing, and custom solver sequences, you can quickly adapt to the ebbs and flows of your requirements. The flexible nature of the COMSOL Desktop environment facilitates further analysis by making “what-if” cases easy to set up and run. You can take your simulation to the production level by optimizing any aspect of your model. Parameter sweeps and objective functions for optimization can be executed directly in the user interface. From start to finish, COMSOL Multiphysics is a complete problem-solving tool.
Using Meshing Sequences
COMSOL Multiphysics provides an interactive meshing environment where, with a few mouse clicks, you can easily mesh individual faces or domains. Each meshing operation is added to the meshing sequence. The final mesh is the result of building all the operations in the meshing sequence. This example demonstrates how to use the meshing sequence ...
Laser Heating of a Silicon Wafer
A silicon wafer is heated up by a laser that moves radially in and out over time. In addition, the wafer itself is rotated on its stage. The incident heat flux from the laser is modeled as a spatially distributed heat source on the surface. The transient thermal response of the wafer is shown. The peak, average, and minimum temperature during the ...
Laser Heating - A Self Guided Tutorial
This tutorial shows how to model transient heat conduction in a glass slab heated by a laser beam. The tutorial emphasizes on the use of functions to model the laser power as a body heat source. Several key design variables have been parameterized. Suggestions on meshing and solver settings are provided. Three different modes of operation are ...
Micromixer - cluster and batch versions
This example studies a laminar static micromixer with two parallel sets of split-reshape-recombine mixing elements. The mixer works through lamination of the streams without any moving parts and the mixing is obtained through diffusion. The purpose of this model is to demonstrate how to access the cluster computing functionality in COMSOL from ...
Modeling a Distributed Model of Thermal Microactuator on a Cluster
A model of a thermal microactuator requires the coupled simulation of electric current conduction with heat generation, heat conduction, and structural stresses and strains due to thermal expansion. The purpose of this model is to demonstrate how to access the cluster computing functionality in COMSOL from COMSOL Desktop and use it to submit a ...
Flow Past a Cylinder
The following model examines unsteady, incompressible flow past a long cylinder placed in a channel at right angle to the oncoming fluid. The cylinder is offset somewhat from the center of the flow to make the steady-state symmetrical flow unstable. The simulation time necessary for a periodic flow pattern to appear is difficult to predict. A ...
Filling of a Capillary Channel: Level Set and Phase Field Models
This example studies a narrow vertical cylinder placed on top of a reservoir filled with water. Because of wall adhesion and surface tension at the air/water interface, water rises through the channel. Surface tension and wall adhesive forces are often used to transport fluid through microchannels in MEMS devices or to measure, transport and ...
Micromixer
The development of mixers does often not only have to account for effectiveness, but also other factors must be involved, such as cost and complexity for manufacturing. The three models study a laminar static micro mixer with two parallel sets of split-reshape-recombine mixing elements. The mixer works through lamination of the streams without ...