Application Builder

Application Builder Features and Functionality

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The COMSOL Multiphysics® software includes the Application Builder, which helps you build custom simulation applications based on your models. By deploying your apps, you can share the power of simulation with colleagues in other departments and to customers outside of your organisation.

Benefits of Simulation Apps

Mathematical Models, Accessible to Everyone

The Application Builder enables simulation experts to create intuitive user interfaces for their computational models — ready-to-use custom applications. The app user is then focused on the input parameters and computational results that matter, without requiring foreknowledge of the underlying model.

The Application Builder is included in the Windows® version of COMSOL Multiphysics® and accessible from the COMSOL Desktop® environment. While you need Windows® to build apps, they can be run on macOS and the Linux®operating system as well.


Comprehensive Simulation Tools for Specific Tasks

COMSOL apps are custom-made simulation tools that contain all the benefits of a model built with the Model Builder, without the extraneous information. The general model can serve as a starting point for several different apps, each with its own restricted input and output options relevant for a specific task.

The Application Builder in COMSOL Multiphysics® provides all functionality needed to build comprehensive simulation apps. For example, you can:

  • Include user documentation, checks for “inputs within bounds”, and predefined reports at the click of a button
  • Build the geometry around a parametric CAD model
  • Import text or binary files with experimental data
  • Configure the app to automatically send an email to a select set of recipients when a computation is finished
  • Generate reports in Microsoft® Word®, Microsoft® PowerPoint®, or HTML formats

Beyond the built-in tools, you can write methods in the Java® programming language. There are very few limitations for what you can include in an app.

'A true Multiphysics platform'

Functionality for Building Apps

The Form Editor

The Form Editor lets you design a user interface by using drag-and-drop capabilities to place widgets such as input fields, buttons, sliders, knobs, check boxes, and radio buttons. No programming is required for this, but the entire process is user-interface driven. If the model makes use of parameters and variables, you link these directly to input fields in the application. In this way, the user of an app can directly edit the values of the parameters and variables that affect the model. In one click, you can include a button in your app that runs a study node and thereby starts the solver. Just as quickly, you can include graphics and numerical outputs. Your apps can have multiple graphics windows with interactive 3D graphics, as well as 2D or 1D graphics.

The Method Editor

The Method Editor provides a programming environment that allows you to write code for actions not covered by the tools in the Model Builder. The methods may, for example, execute loops, process inputs and outputs, and send messages and alerts to the user of the app. The Java® programming language is used to write COMSOL methods, which means that all Java® syntax and Java® libraries can be used. Additionally, the Application Builder has its own built-in library of methods for building applications and modifying the model object. The Application Builder includes several tools for automatically generating code. These tools include conversion of command sequences to methods, recording of code, and code completion, allowing you to get up and running quickly with programming tasks even if you are not familiar with the syntax. The autogenerated code shows you the names of properties, parameters, and variables with tooltips describing their meaning, minimising the need to consult the product documentation.


Testing and Running Apps with COMSOL Multiphysics®

After building an app with the COMSOL Multiphysics® software, you can test and run it from the COMSOL Desktop® using Windows®, macOS, and Linux® operating systems. When you test an app in COMSOL Multiphysics®, it opens a separate window with the app's user interface while keeping the Application Builder desktop environment running. While testing an app, you can apply changes to forms, methods, and the embedded model and they will appear live.

You can also test the app in a web browser. This functionality makes it easy to test the look and feel of the app when it is accessed from a web browser connected to a COMSOL Server™ installation. You can choose which of your installed web browsers you would like the app to launch in. The app will open in a separate browser window with the application's user interface while keeping the Application Builder desktop environment running.


Examples for Inspiration

The Application Libraries, available in both COMSOL Multiphysics® and COMSOL Server™, have lots of examples for you to use and get inspired by when creating your own apps. The Application Libraries include more than 30 example apps that you can run, inspect, modify, or copy contents from into your own apps. Some of these apps function as ready-to-use simulations in their own right, whereas others are for demonstrating certain functionality of the Application Builder or for educational purposes in an academic setting.

Model Builder Features and Functionality

Explore the features and functionality of the Model Builder in more detail by expanding the sections below.

Geometry Modeling and Interfacing with CAD Software
Predefined Interfaces and Features for Physics-Based Modelling
Transparency and Flexibility via Equation-Based Modelling
Automated and Manual Meshing
Study Step Sequences, Parameter Studies, and Optimisation
State-of-the-Art Numerical Methods for Accurate Solutions
Extended Visualisation and Postprocessing Tools for Publication-Ready Modelling Results
Operations, Sequences, and Selections
The core COMSOL Multiphysics® package provides geometry modelling tools for creating parts using solid objects, surfaces, curves, and Boolean operations. Geometries are defined by sequences of operations, where each operation is able to receive input parameters for easy edits and parametric studies in multiphysics models. The connection between the geometry definition and defined physics settings is fully associative — a change in the geometry will automatically propagate related changes throughout the associated model settings.

Geometric entities such as material domains and surfaces can be grouped into selections for subsequent use in physics definitions, meshing, and plotting. Additionally, a sequence of operations can be used to create a parametric geometry part, including its selections, which can then be stored in a Part Library for reuse in multiple models.
Import, Repair, Defeature, and Virtual Operations
The import of all standard CAD and ECAD files into COMSOL Multiphysics® is supported by the CAD Import Module and ECAD Import Module, respectively. The Design Module further extends the available geometry operations in COMSOL Multiphysics®. Both the CAD Import Module and the Design Module provide the ability to repair and defeature geometries. Surface mesh models, such as in the STL format, can also be imported and then converted to a geometry object by the COMSOL Multiphysics® core package. Import operations are like any other operation in the geometry sequence and can be used with selections and associativity for performing parametric and optimisation studies.

As an alternative to the defeature and repair capabilities of the COMSOL® software, so-called virtual operations are also supported to eliminate the impact of artifacts on the mesh, such as sliver and small faces, which do not add to the accuracy of the simulation. In converse to defeaturing, virtual operations do not change the curvature or fidelity of the geometry, while yielding a cleaner mesh.
List of geometry modelling features
  • Primitives
    • Block, sphere, cone torus, ellipsoid, cylinder, helix, pyramid, hexahedron
    • Parametric curve, parametric surface, polygon, Bezier polygon, interpolation curve, point
  • Extrude, revolve, sweep, loft1
  • Boolean operations: Union, intersection, difference, and partition
  • Transformations: Array, copy, mirror, move, rotate, and scale
  • Conversions:
    • Convert to solid, surface, and curve
    • Midsurface1, thicken1, split
  • Chamfer and fillet2
  • Virtual operations
    • Remove details
    • Ignore: Vertices, edges, and faces
    • Form composite: Edges, faces, domains
    • Collapse: Edges, faces
    • Merge: Vertices, edges
    • Mesh control: Vertices, edges, faces, domains
  • Hybrid modelling with solids, surfaces, curves, and points
  • Work Plane with 2D geometry modelling
  • CAD import and interoperability with add-on CAD Import Module, Design Module, and LiveLink™ products for CAD
  • CAD repair and defeaturing with add-on CAD Import Module, Design Module, and LiveLink™ products for CAD
    • Cap faces, delete
    • Fillets, short edges, sliver faces, small faces, faces, spikes
    • Detach faces, knit to solid, repair

1 Requires the Design Module
2 The corresponding 3D operations require the Design Module

The COMSOL® software contains predefined physics interfaces for modelling a wide range of physics phenomena, including many common multiphysics couplings. The physics interfaces are dedicated user interfaces for a particular scientific or engineering field, where all aspects for modelling the phenomena in question are made available for manipulation — from defining the model parameters to discretisation to analysing the results of the solution.

Upon selecting a particular physics interface, the software suggests available study types, such as time-dependent or stationary solvers. The software also automatically recommends the appropriate numerical discretisation of the mathematical model, solver sequence, and visualisation and postprocessing settings that are specific to the physics phenomena. The physics interfaces can also be combined freely in order to describe processes that involve multiple physics phenomena.

The COMSOL Multiphysics® platform is preloaded with a large set of core physics interfaces for fields such as solid mechanics, acoustics, fluid flow, heat transfer, chemical species transport, and electromagnetics. By expanding the core package with add-on modules from the COMSOL® product suite, you unlock a range of more specialised user interfaces that expand modelling capabilities within specific engineering fields.
List of physics-based modeling features

Physics interfaces

  • Electric currents
  • Electrostatics
  • Heat transfer in solids and fluids
  • Joule heating
  • Laminar flow
  • Pressure acoustics
  • Solid mechanics
  • Transport of diluted species
  • Magnetic Fields, 2D
  • Application-specific modules contain many additional physics interfaces


  • Isotropic and anisotropic materials
  • Discontinuous materials
  • Spatially varying materials
  • Time-varying materials
  • Nonlinear material properties as a function of any physical quantity
To really be useful for scientific and engineering studies and innovation, a software has to allow for more than just a hardwired environment. It should be possible to provide and customise your own model definitions based on mathematical equations directly in the user interface. The COMSOL Multiphysics® software offers this level of flexibility with its built-in equation interpreter that can interpret expressions, equations, and other mathematical descriptions on the fly before it generates the numerical model. Adding and customising expressions in the physics interfaces allows for freely coupling them with each other to simulate multiphysics phenomena.

The capabilities for customisation go even further. With the Physics Builder, you can also use your own equations to create new physics interfaces for easy access and manipulation when you want to include them in future models or share them with colleagues.
List of equation-based modelling features
  • Partial differential equations (PDEs)
  • Weak form PDEs
  • Arbitrary Lagrangian-Eulerian (ALE) methods for formulating deformed geometry and moving mesh problems
  • Algebraic equations
  • Ordinary differential equations (ODEs)
  • Differential algebraic equations (DAEs)
  • Sensitivity analysis (optimisation available with add-on Optimisation Module)
  • Curvilinear coordinate computation
For discretising and meshing your model, the COMSOL Multiphysics® software uses different numerical techniques depending on the type of physics, or the combination of physics, that you are studying. The predominant discretisation methods are finite-element based (for a more extensive list of methods, see the solvers section of this page). Accordingly, the general-purpose meshing algorithm creates a mesh with appropriate element types to match the associated numerical methods. For example, the default algorithm may use free tetrahedral meshing or a combination of tetrahedral and boundary-layer meshing, with a combination of element types, in order to provide faster and more accurate results.

For all of the mesh types, mesh refinement, remeshing, or adaptive meshing can be performed during the solution process or study step sequence.
List of meshing features
  • Free tetrahedral meshing
  • Swept mesh with prism and hex elements
  • Boundary-layer meshing
  • Tetrahedral, prism, pyramid, and hexahedral volume elements
  • Free triangular meshing of 3D surfaces and 2D models
  • Mapped and free quad meshing of 3D surfaces and 2D models
  • Copy mesh operation
  • Virtual geometry operations
  • Mesh partitioning of domains, boundaries, and edges
  • Import and edit functionality for externally generated meshes
Study or Analysis Types
When you select a physics interface, a number of different studies (analysis types) are suggested by COMSOL Multiphysics®. For example, for solid mechanics analyses, the software suggests time-dependent, stationary, or eigenfrequency studies; for CFD problems, the software would only suggest time-dependent and stationary studies. Other study types can also be freely selected for any analysis that you perform. Study step sequences structure the solution process to allow you to select the model variables for which you want to solve in each study step. The solution from any of the previous study steps can be used as input to a subsequent study step.
Sweeps, Optimisation, and Estimations

Any study step can be run with a parametric sweep, which can include one or multiple parameters in a model, from geometry parameters to settings in the physics definitions. Sweeps can also be performed using different materials and their defined properties, as well as over lists of defined functions.

Optimisation studies, using the Optimisation Module, can be performed for topology optimisation, shape optimisation, or parameter estimations based on a multiphysics model. COMSOL Multiphysics® offers both gradient-free and gradient-based methods for optimisation. For parameter estimation, least-squares formulations and general optimisation problem formulations are available. Built-in sensitivity studies are also available, where they compute the sensitivity of an objective function with respect to any parameter in the model.

List of studies
  • Stationary
  • Time Dependent
  • Eigenfrequency
  • Eigenvalue
  • Frequency Domain
  • Parametric Sweep
  • Function Sweep
  • Material Sweep
  • Sensitivity
  • Model Reduction
  • Optimisation and Parameter Estimation
    • Coordinate Search
    • Monte Carlo
    • Nelder-Mead
    • BOBYQA
    • COBYLA
    • SNOPT
    • MMA
    • Levenberg-Marquardt
The equation interpreter in the COMSOL Multiphysics® software delivers the best possible fuel to the numerical engine: the fully coupled system of PDEs for stationary (steady), time-dependent, frequency-domain, and eigenfrequency studies. The system of PDEs is discretised using the finite element method (FEM) for the space variables (x, y, z). For some types of problems, the boundary element method (BEM) can also be used to discretize space. For space- and time-dependent problems, the method of lines is used, where space is discretised with FEM (or BEM), thus forming a system of ordinary differential equations (ODEs). These ODEs are then solved using advanced methods, including implicit and explicit methods for time stepping.

Time-dependent and stationary (steady) problems can be nonlinear, also forming nonlinear equation systems after discretisation. The engine in COMSOL Multiphysics® delivers the fully coupled Jacobian matrix, which is the compass that points the nonlinear solver to the solution. A damped Newton method is used for solving the nonlinear system for stationary problems or during time stepping for time-dependent problems. The Newton method then solves a sequence of linear equation systems, using the Jacobian matrix, in order to find the solution to the nonlinear system.

For linear problems (also solved in the steps of the nonlinear solver, see above), the COMSOL® software provides direct and iterative solvers. The direct solvers can be used for small- and midrange-sized problems, while the iterative solvers can be used for larger linear systems. The COMSOL® software provides a number of iterative solvers with cutting-edge preconditioners, such as multigrid preconditioners. These preconditioners provide robustness and speed in the iterative solution process.

The different physics interfaces can also provide the solver settings with suggestions on the best possible default settings for a family of problems. These settings are not hardwired; you can change and manually configure the solver settings directly under each solver node in the user interface to tune the performance for your specific problem. When available, the solvers and other computationally intense algorithms are fully parallelised to make use of multicore and cluster computing. Both shared and distributed memory methods are available for direct and iterative solvers as well as for large parametric sweeps. All steps of the solution process can make use of parallel computing.
List of solvers
  • Space discretisation:
    • FEM
      • Nodal-based Lagrange elements and serendipity elements of different orders
      • Curl elements (also called vector or edge elements)
      • Petrov-Galerkin and Galerkin least square methods for convection-dominated problems and fluid flow
      • Adaptive mesh and automatic mesh refinement during the solution process
    • BEM
    • Discontinuous Galerkin method
  • Space-time discretisation:
    • Method of lines (FEM and BEM for space)
  • ODE and DAE time-stepping solvers:
    • Implicit methods for stiff problems (BDF)
    • Explicit methods for nonstiff problems
  • Nonlinear algebraic systems:
    • Damped Newton methods
    • Double dog-leg
  • Linear algebraic systems:
    • Direct dense solvers: LAPACK
    • Direct sparse solvers: MUMPS, PARDISO, SPOOLES
    • Iterative sparse solvers: GMRES, FGMRES, BiCGStab, conjugate gradients, TFQMR
      • Preconditioners: SOR, Jacobi, Vanka, SCGS, SOR Line/Gauge/Vector, geometric multigrid (GMG), algebraic multigrid (AMG), Auxiliary Maxwell Space (AMS), Incomplete LU, Krylov, domain decomposition
      • All preconditioners can potentially be used as iterative solvers
  • Additional discretisation methods are available in add-on products, including particle and ray tracing methods

Show off your results to the world. COMSOL Multiphysics® sports powerful visualisation and postprocessing tools so that you can present your results in a meaningful and polished manner. You can use the built-in tools or expand your visualisations with derived physical quantities by entering mathematical expressions into the software. Therefore, you can visualise just about any quantity of interest related to your simulation results in COMSOL Multiphysics®.

Visualisation capabilities include surface, slice, isosurface, cut plane, arrow, and streamline plots, to name just a few plot types. A range of numerical postprocessing tools are available for evaluation of expressions, such as integrals and derivatives. You can compute the max, min, average, and integrated values of any quantity or derived quantities throughout volumes, on surfaces, along curved edges, and at points. Postprocessing tools specific to certain areas of engineering and science have also been included in many of the physics-based modules.

Exporting Results and Generating Reports with Other Software

You can export data and process it via third-party tools. Numerical results can be exported to text files on the .txt, .dat, and .csv formats as well as to the unstructured VTK format. With LiveLink™ for Excel®, results can be exported to the Microsoft®Excel® spreadsheet software file format (.xlsx). Images can be exported to several common image formats, as well as the glTF™ file format for exporting 3D scenes. Animations can be exported in the WebM format and as animated GIF, Adobe®Flash® technology, or AVI files. Reports summarising the entire simulation project can be exported to HTML (.htm, .html) or Microsoft® Word® software format (.doc).

List of results and postprocessing features
  • Visualisation
    • Surface plots
    • Isosurface plots
    • Arrow plots
    • Slice plots
    • Streamline plots
    • Contour plots
  • Postprocessing
    • Integration, average, max, and min of arbitrary quantities over volumes, surfaces, edges, and points
    • Custom mathematical expressions including field variables, their derivatives, spatial coordinates, time, and complex-valued quantities
    • Specialised postprocessing and evaluation techniques are included in many of the physics-based modules
  • Support for 3Dconnexion® SpaceMouse® devices
  • Import and export
    • Text
    • Microsoft® Excel® .xlsx format
    • Images
    • Animations
    • Mesh
    • CAD formats
    • And more

Every business and every simulation need is different.

In order to fully evaluate whether or not the COMSOL Multiphysics® software will meet your requirements, you need to contact us. By talking to one of our sales representatives, you will get personalised recommendations and fully documented examples to help you get the most out of your evaluation and guide you to choose the best license option to suit your needs.

Fill in your contact details and any specific comments or questions, and submit. You will receive a response from a sales representative within one business day.

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