A number of new improvements have been added to COMSOL Multiphysics and its add-on products as part of the Version 3.5a release.

## COMSOL Multiphysics and Modules

### General new improvements

- Overall performance improvements:
- General improvements to the FEM assembly process introduce significant speed improvements, depending on the model, for single core processors. The improvement ranges between 10-100% and can be as high a factor 30 in a few cases
- General improvements in linear solvers range between 5-20%
- Various improvements in the time-dependent solvers can result in improvements in solution times by a factor 2-8.
- Multicore speedup is increased by 5-30%
- General improvements give about a 10% decrease in memory consumption

- Support for the Intel 64-bit Mac version
- Application modes for optimization (requires Optimization Lab) and sensitivity analysis have been introduced. These include support for inverse modeling, parameter estimation, geometry optimization (shape optimization), and topology optimization
- About 10 new models showcasing the new functionality for parameter estimation, inverse modeling, and optimization have been included
- Unstructured function evaluation (import of data from unstructured grids) is now supported

### Meshing:

- Ability to mesh the Parasolid geometry representation directly (with the CAD Import Module) has been included
- Improved boundary layer meshing abilities
- Improved mesh sweeping, which now supports “N-to-1 sweeps”
- Conversion of a mixed mesh consisting of quads, hexes, or/and prisms to a mesh consisting of only tetrahedrons or triangles with GUI support
- Free-field NASTRAN format import

### Postprocessing:

- Support for GIF as an image format and for creating animated GIFs
- Ability to plot while solving Click to view a Demo
- Customized color tables are now possible
- “Accurate derivative recovery” for more accurate postprocessing of stresses, fluxes, etc
- Summation integration method for computation of reaction forces, etc has been included
- Support for shared-memory parallelism providing speedup of slice plots, isosurface plots, subdomain plots, boundary plots, edge plots, deformed-shape plots, and streamline plots (in 3D) and surface plots, contour plots, and boundary plots, and deformed-shape plots

### Solvers:

- Improved and generalized stationary segregated solver providing large performance improvements (speed and memory) for important classes of one-way coupled (weakly coupled) multiphysics problems such as thermal stress models
- Introduction of a transient segregated solver for better performance when solving transient multiphysics problems
- Introduction of a generalized-alpha transient solver that provides improved solution of transient wave problems (electromagnetics, acoustics, structures, etc.) and fluid-dynamics problems. The generalized-alpha solver can improve performance by a factor of 2-8 for typical problems (with the same accuracy)
- Introduction of BiCGStab solver
- Inclusion of an out-of-core direct solver (PARDISO)
- Possibility for functional-based h (mesh) adaption
- Improved shared-memory parallelism (OpenMP version of SPOOLES, parallel postprocessing)
- The parametric solver now supports multiple parameters
- Parametric sweep functionality has been greatly improved through providing a single solver call that performs several runs using the currently selected solver while varying a set of model parameters
- Limited support for distributed-memory parallelism has also been included – where running sweeps on Linux clusters results in a speedup factor near n for clusters with n nodes.

## Add-on Products

### AC/DC Module

- Possibility to specify voltage and current levels for ports is now included
- Import of PCB designs made in Cadence Allegro and Mentor Graphics Board Station and other software that supports the XML version of Valor's ODB++ format.
- Import of PCB designs from any ECAD software package through the use of the software NETEX-G from Artwork and generic Gerber and drill file formats.
- Force computation through the principle of virtual work (predefined in the user interface)
- Reduced-field form for quasistatic/static model, making it possible to specify a known background field and solve only for the reduced field

### Acoustics Module

- Acoustics-structure interaction (predefined multiphysics) application mode has now been included
- Predefined variables for reaction forces and summation method for general reaction-force computations is now available

### CAD Import Module

- Parasolid is now used in all steps of the CAD import process. Therefore, no conversion to COMSOL geometry objects is necessary for the two following items:
- Parasolid’s geometry representation is used directly by COMSOL's mesher
- Parasolid is used to find pairs in CAD assemblies

- More flexible defeaturing: you can repair and defeature each part of an assembly independently
- Support for geometric parametric sweeps (also on Linux clusters) in the SolidWorks and Autodesk Inventor bidirectional interfaces
- Bidirectional interface to Autodesk Inventor
- The CAD Import Module is now available for the Mac platform
- Improved stability through improved quality of the internal COMSOL geometry engine

### Chemical Engineering Module

- Improved stabilization of the Navier-Stokes equations providing large performance improvements
- With the combined improvements in assembly, iterative solvers, and stabilization techniques, many CFD models run 4-8 times faster
- Stabilization of the level set equation for improved multiphase flow modeling
- Phase field application mode for multiphase flow modeling using the phase field method has been introduced Click to view a demo of this application
- Mass source is now available in the Brinkman equation
- A viscoplastic model example has been included
- Improved Liquid and Gases material library with data for liquid/gas surface tension and liquid/liquid interfacial tensions is now available

### Earth Science Module

- Predefined multiphysics interface for modeling of poroelasticity has been introduced
- Improved stabilization of the Navier-Stokes equations providing large performance improvements
- Mass source is now available in the Brinkman equation
- Improved Liquid and Gases material library with data for liquid/gas surface tension and liquid/liquid interfacial tensions is now available

### Heat Transfer Module

- Axisymmetric radiation can now be modeled
- Predefined multiphysics entries for flow with variable density is now included
- Predefined multiphysics entries for fluid-solid thermal interaction/conjugate heat transfer has been introduced
- Improved Galerkin least-squares (GLS) method for streamline diffusion

### MEMS Module

- General support for damping and losses in piezo (structural damping plus dielectric and coupling losses) has been included
- Stress stiffening and large deformations in piezo applications is now possible
- SPICE circuit support has been included
- ECAD import has been introduced (see AC/DC Module)
- Stabilization of the level set equation for improved multiphase flow modeling
- Phase field application mode for multiphase flow modeling using the phase field method has been introduced Click to view a demo of this application
- All new features that have also been included in the Structural Mechanics Module

### RF Module

- SPICE circuit support has been included
- ECAD import has been introduced (see AC/DC Module)
- Introduction of circuit ports for wave applications, such as modeling the connection of a transmission line or an antenna to an external circuit
- An improved axisymmetric formulation

### Structural Mechanics Module

- Viscoelastic material model has been included
- Hyperelastic Murnaghan material model for modeling of nonlinear acoustoelasticity has also been introduced
- Predefined variables for reaction forces and summation method for general reaction-force computations is now possible
- Mechanical heating support defining entropy etc. (now in all space dimensions) is available
- The thermal-electric-structural interaction (predefined multiphysics entry) simplifies modeling of Joule heating with thermal stress effects
- Improvements in assembly and solvers that increases solution speed by 5-30% for typical 3D problems