Use a COMSOL command to start COMSOL products with detailed start-up options.

where square brackets indicate optional arguments. There are several different commands (See <command> in the command syntax) that can be combined with optional targets to achieve various results. The table below lists the major available commands and targets (if the Availability column is empty, the command is always available):

The commands are available in the bin\win64 subdirectory in the COMSOL installation directory. The COMSOL installer sets up a few of the possible commands on your Start menu and your desktop. In Windows 8, 8.1, and 10, you can click the shortcut COMSOL Launchers on the Apps screen. This makes a folder with shortcuts to all COMSOL commands available.

To create additional customized commands, you can create shortcuts including all argument and put them on your desktop. You can also issue COMSOL commands in a command window. To conveniently access the command in a command window, you need to set up the Windows path to include the path bin\win64 in the COMSOL installation directory.

For each launcher file, there is a corresponding .ini file in the same directory. It is sometimes recommended that these files are edited. For example, you can add options to any of the above commands by modifying the corresponding INI file. To change the option opt to value val, add the line

to the file comsol.ini. Change the file comsolbatch.ini for comsolbatch, and similarly for the other COMSOL targets.

You can enter various options after the COMSOL command and target. Table 22-2 lists the options (See [<options>] in the command syntax) available for all COMSOL commands. Always issue these options between the command and the target (if any).

For the -tmpdir option, the COMSOL Multiphysics software uses the specified directory to store temporary files. As an alternative, you can use the COMSOL_TMPDIR environment variable. Use the -prefsdir option to specify the directory where COMSOL Multiphysics stores the preference file.

In a default COMSOL installation, the documentation files are located in the directory doc under the installation root directory. You can use the -docroot option if you want to move the documentation directory to a different location. Similarly, use the -applicationsroot option if you want to move the Application Libraries root directory applications from its default location under the COMSOL installation root. Relocating the documentation and Application Libraries root directories can be useful for administering an Application Library update; see The Application Library Update Window.

It is also possible to import and export preference settings using the Preferences dialog box in the COMSOL Desktop.

Use the option -np to control the number of cores used. The default is to use all available cores (processing units).

Use the option -numasets to control the number of nonuniform memory access (NUMA) node sets that the COMSOL Multiphysics software should take into account. This is usually the number of processor sockets that the hardware is using. Note that -numasets 1 represents the case where there is only one nonuniform memory access node — that is, the entire computer. If you only set the -np option, the number of sockets is determined automatically so that sufficient number of sockets are used by default. The -np flag, together with the -numasets flag, decides the size of a NUMA set (that is, -np divided by -numasets). The purpose of -numafirst is to decide which processor core number to place the first NUMA set on (that is, the size of the NUMA set times numafirst).

Depending on how loaded the machine is, you can control how COMSOL Multiphysics uses the available processors with the -mpmode option. The following options are available:

Use the option -alloc to specify memory allocator type. The default is to use the native memory allocator for computers with less than eight cores and otherwise the scalable memory allocator. The scalable memory allocator can increase performance significantly for computers with many cores but uses more memory.

If you want to use a different BLAS library than the ones provided by COMSOL, make sure that COMSOL Multiphysics can find the library. The simplest way for COMSOL Multiphysics to find a library is to put it in /lib/win64 or somewhere in the standard search path. Also provide the path to any sublibraries needed by the library. Set the search path to point to the directory where the library is installed. To do so, use the environment variable PATH. Your library must support both the standard FORTRAN LAPACK interface and the standard FORTRAN BLAS interface. If your LAPACK and BLAS interface consists of several libraries, use the path to the LAPACK library.

The following options are used to specify inputs to an application with command-line options.Find more information about these options in the section The Application Argument Node in the Application Builder Reference Manual.

In additions to the options in Table 22-2, the standalone COMSOL command supports the following options on Windows:

For example, use comsol -open myapp.mph to open an application. Applications can be run or edited with the two other options.

Use a COMSOL Multiphysics server command to start a COMSOL process ready to process computational requests. A COMSOL Multiphysics server listens for TCP/IP connections from COMSOL Multiphysics clients. A COMSOL Desktop can become a COMSOL Multiphysics client by connecting to a COMSOL Multiphysics server. The LiveLink™ for MATLAB® also needs to connect to a COMSOL Multiphysics server.

The server computer can be accessed in several ways. You can log in to a machine that is dedicated to a single person. You can also connect to the server computer by using Remote Desktop. Start the COMSOL Multiphysics server from the Start menu. If several people want to access a single Windows computer to run the COMSOL Multiphysics server, you must use Windows Terminal Server or another tool that allows multiple users to log in on the same Windows server. In some Windows versions, Microsoft® provides a Telnet Server with which you can log in through a terminal window. When using a terminal window to log in on Windows, use the comsolmphserver command to start the COMSOL Multiphysics server.

When a COMSOL Multiphysics server is started for the first time, you are asked for a username and password. Select a username and a password, which COMSOL Multiphysics then uses in communications between the COMSOL Multiphysics client and the server. You must also specify a matching username and password in the Connect to Server dialog box. The software writes this login information in the subdirectory .comsol/v54/login.properties in your Windows home directory.

To enhance security, you can limit the address range that can access the COMSOL Multiphysics server, both in your firewall and by changing the COMSOL Multiphysics server configuration. To limit the allowed address range in the server, edit the file <COMSOL Installation Directory>\bin\tomcat\conf\server.xml and find the lines:

and follow the instructions. The default port for the COMSOL Multiphysics server is 2036. You can change this by using the option -port <port> when launching COMSOL and COMSOL Multiphysics server.

To enhance security, you can limit the address range that can access the documentation server, both in your firewall and by changing the documentation server configuration. To limit the allowed address range in the server, edit the file <COMSOL Installation Directory>\doc\help\conf\server.xml and find the lines:

and follow the instructions. The default port for the documentation server is 8090. You can change this by using the option -docport <docport> when launching COMSOL Multiphysics.

where <level> is the level to stop the process on. Set the level to a high value in order to stop as soon as possible. By default, it is set to 100. The -inputfile option indicates the filename of the model that another process is running. The inputfile arguments should be consistent with the one specified to launch another process. That is, either the same inputfile arguments should be provided or the -inputfile should be the same as the -outputfile specified to launch another process.

This command starts COMSOL Batch, solves the model in the Model MPH-file with the given filename (in.mph in this example) using the active solver settings in the model, and stores the solution in the out.mph. You can also use multiple sets of input files and output files, stored in a file using the -jobfile option.

The -study option directs COMSOL Multiphysics to run a certain study. The study is identified by its tag. In the COMSOL Desktop, select Show Name and Tag under Model Builder Node Label to see the tags of the jobs under Study within curly braces in the Model Builder. In the model object, determine the tags of the jobs by the command model.study().tags(). You can determine the name of each study by model.study(<tag>).name() using one of the job tags.

The -job option works similar to the -study option. It directs COMSOL Multiphysics to start a certain job. The job is identified by its tag. In the model object, determine the tags of the jobs by the command model.batch().tags(). You can determine the name of each job by model.batch(<tag>).name() using one of the job tags.

The -usebatchlic option makes COMSOL use batch licenses for the job. This option is equivalent to the Use batch license check box available in the Cluster Computing and Cluster Sweep study nodes. Using batch licenses for a cluster computing or cluster sweep job means that you can continue working in the COMSOL Desktop while the job is running using only a single FNL license.

For the -recover option, the working directory (where all .log, and .status files are generated) will contain the .recovery file, which contains information about the recovery folder in the case that the COMSOL software stops working. If the -recover option is specified, the model from the recovery directory will be opened. If opening that model succeeds, a continue operation will be performed; otherwise, the input filename model will be simulated.

When -mode is batch (the default), all Batch and Cluster Computing settings are ignored: that is, Batch and Cluster Computing features will not start any batch jobs as they will do when you click Compute in the COMSOL Desktop.

When -mode is desktop, Batch and Cluster Computing settings will be used. This case corresponds to clicking Compute in the COMSOL Desktop. All paths in the Batch and Cluster Computing nodes must correspond to paths that you would set up in the COMSOL Desktop if you started it and clicked Compute instead of running the COMSOL batch command.

You can provide parameters as parameter names and corresponding values using the -pname and -plist arguments, respectively. For example, -pname a,b -plist 1,2 corresponds to

which means that any global parameters with the same names are overwritten by these new values. The model will then use these new values. Also note that the model is saved with a new name that contains the parameter tuple. Parametric sweeps will work as if you set the global parameters a to 1 and b to 2 and then compute a parametric sweep. Multiple tuples (such as -plist 1,2,3,4) will be saved in multiple files.

The comsolcompile command compiles a model file for Java for use by the COMSOL batch command or for loading class files into the GUI. With COMSOL Compiler, you can also use it to compile COMSOL apps into standalone executable apps. The Windows syntax for the COMSOL compile command is

Options not given are taken from the application’s Compiler node, except for -outputdir and -platforms.

If you need to start COMSOL cluster jobs from the command line, the preferred way is to use the comsolclusterbatch command because the comsolclustermphserver and comsolcluster commands require TCP/IP access from your client computer to the cluster node where COMSOL Multiphysics runs.

which is located in the Microsoft MPI installation subfolder Bin, as the user that will run the MPI job. You can then start the distributed mode by replacing the previous mpiexec -n <number of nodes> syntax with

Here the mpiexec command is located in the same folder as smpd, and the local node should be listed first in the list of computer names if you want to run interactively. To start COMSOL Desktop in distributed mode, use the syntax

to run a COMSOL batch job on a number of computational nodes given by mpiexec. For further information about the mpiexec command and Windows HPC Server, consult the documentation that was shipped with the product and the online manuals.

When a COMSOL Multiphysics server cluster job is created, a preference directory must be set and be reachable from all nodes to avoid problems with the server login; see The COMSOL Commands and Login Information. The preferences can be generated by starting COMSOL Multiphysics server once on the head node using the following command:

where <prefsdir> is a preference directory common to all nodes.

The COMSOL cluster target arguments specify what MPI library to use and what Scalapack version to use. There are several implementations of MPI. COMSOL by default uses the Windows HPC Server libraries. The COMSOL software also supports most MPI implementations based on MPICH2. It is recommended that the default library is used. In addition, the COMSOL software includes a compatibility mode, which you activate by adding the option -mpi mpich2. When using this option, both the variables PATH and LD_LIBRARY_PATH must include the MPI implementation. It is also possible to use other MPI libraries based on MPICH2 using the option -mpipath <path to shared library>. The following options are available for COMSOL cluster commands:

The Cluster Computing study allows you to set up a batch job for submission to a Windows HPC Server job scheduler. There are several settings that you can configure in the comsol.ini file to get default settings:

These two lines add commands prior to the comsol command and after the comsol command, respectively. You can add {nn} or {perhost} to any of these pre- and postcommands, which configures the Cluster Computing study to use the number of nodes and number of nodes on each host from the corresponding settings for the Cluster Computing study. For more information, see Cluster Computing.

Use the COMSOL matlab command to access the COMSOL API through MATLAB. Enter the following command:

The following options are available for the comsolmphserver matlab command: