Electrostatic Current and Voltage

Multipliers

There are two multipliers that control the magnitudes of various electrostatic loads when they are applied to the model. These are located in the Analysis Parameters dialog box on the General tab. The value Boundary voltage multiplier multiplies the magnitudes of any applied voltages on the model. The value in Current or charge sources multiplier multiplies the magnitudes for any charge or current loads on the model.

A value of zero in any of these fields except for Boundary voltage multiplier disables the loads of that type in the model. A value of 0 in Boundary voltage multiplier changes the magnitudes of the applied voltages to 0.

Calculate Flow Lines for 2D Models

For 2D models, if the Invoke flow-line generator check box in the Options tab of the Analysis Parameters dialog is activated, the contours of the flow of the current through the model are calculated. These contours are viewable in the Results environment.

Solver Options Section

The type of solver for an electrostatic analysis can be selected in the Analysis Parameters dialog box, Solution tab, in Type of solver. See also Types of Solvers Available for background information. The options available are as follows:

• Automatic When selected, the processor chooses between the Iterative (AMG) and Sparse options based on the model size. The sparse solver is the optimum solver for mid-sized models. The iterative solver is the optimum solver for large models and requires less RAM. If a 64 bit processor is available on the system, the iterative and BCSLIB-EXT solver takes advantage of it.
• Sparse Uses one of two available sparse solvers available in the Type of sparse solver drop-down box. The sparse solvers use multiple threads/cores when available.
• Iterative (AMG) Uses an iterative scheme to solve the system of equations. The iterative solver uses multiple threads/cores when available.

If you want to create the solution matrix, but not perform the analysis, activate the check box for Stop after stiffness calculations. The only time it is useful is if you must access the equation number matrix. Otherwise, the stiffness matrix is always calculated when running an analysis, so there is no advantage to use this option in normal circumstances.

For the sparse and iterative solvers, the Percent memory allocation field controls how much of the available RAM is used to read the element data and to assemble the matrices. A small value is recommended. (When the value is less than or equal to 100%, the available physical memory is used. When the value of this input is greater than 100%, the memory allocation uses available physical and virtual memory.)

As listed above, some of the solvers take advantage of multiple threads/cores available on the computer. The drop-down Number of threads/cores control is enabled in such situations. You want to use all the threads/cores available for the fastest solution, but might choose to use fewer threads/cores if you need some computing power to run other applications at the same time as the analysis.

Iterative Solver Section

If the iterative solver is chosen, then the Iterative Solver section is enabled. The input for this section is as follows:

• The Convergence tolerance field determines how accurate a solution is found to the matrix of equations. The smaller the tolerance, the more accurate the solution.
• Maximum number of iterations stops the analysis if the matrix of equations is not solved within this number of iterations.
  Attention: The accuracy of the solution depends on the convergence tolerance. A smaller tolerance results in a more accurate solution but may take more iterations. As with any iterative solution, check the results to confirm that they meet the appropriate accuracy. In some cases, performing the analysis twice with a different convergence tolerance is the best way to confirm the accuracy.

Sparse Solver Section

When chosen, the Sparse Solver section is enabled. The input is:

• Type of sparse solver contains a list of sparse solvers currently available. (The sparse solvers are available only for the Windows operating system.) The sparse solvers available are as follows:
  • Default use BCSLIB-EXT solver.
  • BCSLIB-EXT use the Boeing solver. The BCSLIB-EXT solver can write temporary files to the folder specified by the environment variable USERPROFILE. By default, this variable is set to the folder C:\Documents and Settings\Username where C: is the drive on which the operating system is installed. The error numbers -701 or -804 returned from the BCSLIB-EXT solver means that it ran out of hard disk space for storing the temporary files. If this occurs, change the USERPROFILE variable to a directory that can provide sufficient hard disk space. (See the Windows Help and Support for documentation on changing environment variables.)
• Solver memory allocation sets the amount of memory to use during the sparse matrix solution for the BCSLIB-EXT solver. Allocating more memory results in a faster analysis. The other sparse solvers adjust the memory setting automatically, so no setting is required for them.

Control Data in Text Output Files

After the analysis is complete, the analysis results can be output to a text file. Use the Analysis Parameters dialog box, Output tab, to control the data that is output to this file.