Use the Stationary Solver (
) to find the solution to linear and nonlinear stationary problems (also called static or steady-state problems). This solver is automatically used when a Stationary or Frequency Domain study is added to the model.
) to find the solution to linear and nonlinear stationary problems (also called static or steady-state problems). This solver is automatically used when a Stationary or Frequency Domain study is added to the model.Also see About the Stationary Solver for information about Damped Newton Methods, Linear Solvers vs. Nonlinear Solvers, and Pseudo Time Stepping.
Use the Defined by study step list to specify if the settings are synchronized with the corresponding study step.
The number in the Relative tolerance field (default: 0.001) is used for tolerance-based termination of iterative solver processes and for error checking (if enabled) for direct linear system solvers.
 |
The termination tolerance used for iterative processes is also influenced by values specified in the Tolerance factor fields present in active Fully Coupled, Segregated, and Segregated Step subnodes. See Termination Criterion for the Fully Coupled and Segregated Attribute Nodes for details.
|
Use the Linearity list to specify whether to use a nonlinear or linear solver. Select:
|
•
|
Automatic to perform an analysis that automatically detects if the problem can be solved with a linear solver approach. If this option is selected, no other settings are required.
|
|
•
|
Linear to use a linear solver. This option uses the same linearization point for both residual and Jacobian computation and corresponds to one step in Newton’s method.
|
|
•
|
Linear perturbation to use a linear solver. This option computes the Jacobian in the same way as the Linear option but uses a zero solution when computing the residual. It is useful for small-signal analysis and similar applications where the variations around a linearization point are of interest.
|
|
•
|
Nonlinear to use a nonlinear solver. If this option is selected, no other settings are required.
|
If Linear or Linear perturbation is selected, COMSOL assumes that the problem to be solved is a linearization about a solution. Specify such a solution (a linearization point) using the Prescribed by list. Select:
|
•
|
Initial expression to use the expressions specified on the Initial Values nodes under a specific physics interface as a linearization point.
|
|
•
|
Solution to use a solution as a linearization point. Use the Solution list to specify which solution to use if Prescribed by has been set to Solution. Select:
|
|
-
|
Zero to use a linearization point that is identically equal to zero.
|
|
-
|
Any other solution to use it as linearization point. It can be the current solution in the sequence or a solution from another sequence or a solution that was stored with the Solution Store node. You select a stored solution by changing Use to the name of the stored solution.
|
Select the Store linearization point and deviation in output check box to store the used linearization point. Also see Linear Solvers vs. Nonlinear Solvers.
Select the Reaction forces check box to compute and store reaction forces in the output.
The computation of boundary flux variables involves solving a system of equations to obtain a continuous field from nodal flux values. If the Use lumping when computing fluxes check box is selected, this system of equations is lumped. The benefits of using this option is that it can avoid certain spurious oscillations in the computed flux field and that it is slightly faster. Lumping is not suitable in 3D for shape functions of order higher than 1.
 |
To enable these settings, select User defined from the Defined by study step list under General. Select the Plot check box to allow plotting of results while solving in the Graphics window. Then select what to plot from the Plot group list and, for time dependent simulations, at which time steps to update the plot: the output times or the time steps taken by the solver. The software plots the data set of the selected plot group as soon as the results become available. You can also control which probes to tabulate and plot the values from. The default is to tabulate and plot the values from all probes in the Table window and a Probe Plot window.
Use the Probes list to select any probes to evaluate. The default is All, which selects all probes for plotting and tabulation of probe data. Select Manual to open a list with all available probes. Use the Move Up (
), Move Down (
), Delete (
), and Add (
) buttons to make the list contain the probes that you want to see results from while solving. Select None to not include any probe.
), Move Down (), Delete (), and Add () buttons to make the list contain the probes that you want to see results from while solving. Select None to not include any probe.In this section you can define constants that can be used as temporary constants in the solver. You can use the constants in the model or to define values for internal solver parameters. Click the Add (
) button to add a constant and then define its name in the Constant name column and its value (a numerical value or parameter expression) in the Constant value column. By default, any defined parameters are first added as the constant names, but you can change the names to define other constants. Click Delete (
) to remove the selected constant from the list.
) button to add a constant and then define its name in the Constant name column and its value (a numerical value or parameter expression) in the Constant value column. By default, any defined parameters are first added as the constant names, but you can change the names to define other constants. Click Delete () to remove the selected constant from the list.This section, which is initially empty, contains a log from the time stepping. It is not available when the stationary solver is a subnode to another solver. This log is stored in the Model MPH-file. Select the Keep warnings in stored log to keep warning messages in this log so that the information in those warnings is also available when reopening the model.
 |
|
 |