34.9.2 Parallel/Partitioning and Load Balancing...

The Parallel/Partitioning and Load Balancing... menu item opens the Partitioning and Load Balancing dialog box.

Partitioning and Load Balancing Dialog Box

The Partitioning and Load Balancing dialog box allows you to partition the mesh into separate clusters of cells for separate processors on a parallel computer. Note that the Partitioning and Load Balancing dialog box is slightly different in the serial and parallel solvers. See Section  32.5.4 for details.

The Partitioning and Load Balancing dialog box also allows you to enable and control ANSYS FLUENT's load balancing feature. Load balancing will automatically detect and analyze parallel performance, and redistribute cells between the existing compute nodes to optimize it. See Section  32.5.5 for more information about load balancing.

Controls

Method   contains a drop-down list of the recursive partition methods that can be used to create the mesh partitions. The choices include the Cartesian Axes, Cartesian Strip, Cartesian X-Coordinate, Cartesian Y-Coordinate, Cartesian Z-Coordinate, Cartesian R Axes, Cartesian RX-Coordinate, Cartesian RY-Coordinate, Cartesian RZ-Coordinate, Cylindrical Axes, Cylindrical R-Coordinate, Cylindrical Theta-Coordinate, Cylindrical Z-Coordinate, Metis, Polar Axes, Polar R-Coordinate, Polar Theta-Coordinate, Principal Axes, Principal Strip, Principal X-Coordinate, Principal Y-Coordinate, Principal Z-Coordinate, Spherical Axes, Spherical Rho-Coordinate, Spherical Theta-Coordinate, and Spherical Phi-Coordinate techniques, which are described in Section  32.5.6.

Options   tab

Number of Partitions   defines the desired number of mesh partitions. This usually matches the number of processors available for parallel computing.

Reporting Verbosity   specifies the amount of information to be reported in the text (console) window during the partitioning. With the default value of 1, the solver will print the number of partitions created, the number of bisections performed, the time required for the partitioning, and the minimum and maximum cell, face, interface, and face-ratio variations. (See Section  32.5.7 for details.) If you increase the Reporting Verbosity to 2, the partition method used, the partition ID, number of cells, faces, and interfaces, and the ratio of interfaces to faces for each partition will also be printed in the console window. If you decrease the Reporting Verbosity to 0, only the number of partitions created and the time required for the partitioning will be reported.

Across Zones   allows partitions to cross zone boundaries (the default). If turned off, it will restrict partitioning to within each cell zone. This is recommended only when cells in different zones require significantly different amounts of computation during the solution phase, for example if the domain contains both solid and fluid zones.

Encapsulate Mesh Interfaces   allows you to force the cells surrounding all non-conformal mesh interfaces in your mesh to reside in a single partition at all times during the calculation. See Section  32.5.5 for information on using this option.

Encapsulate for Adaption   (available only when Encapsulate Mesh Interfaces is turned on) allows you to encapsulate additional layers of cells in the same partition, such that transfer of cells will be unnecessary during parallel adaption.

Optimization   tab contains toggle buttons for activating schemes to optimize the partitions created by the selected partition method. In addition, the optimization scheme will be applied until appropriate criteria are met, or the maximum number of iterations have been executed. If the Iterations counter is set to 0, the optimization scheme will be applied until completion, without limit on the maximum number of iterations.

Merge   attempts to decrease the number of interfaces by eliminating orphan cell clusters (an orphan cluster is a group of connected cells whose members each have at least one face coincident with an interface boundary).

Smooth   attempts to minimize the number of interfaces by sacrificing cells on the partition boundary to the neighboring partition to reduce the partition boundary surface area.

Pre-Test   instructs the solver to test all coordinate directions and choose the one which yields the fewest partition interfaces for the final bisection. Note that this option is available only when you choose Principal Axes or Cartesian Axes as the partitioning method.

Weighting   tab allows you to set the appropriate weights, prior to partitioning the mesh.

Weight Types   allows you to turn on/off a specific weight. Weight types include: Cell Type, Solid Zones (available only if solid cell zones are defined); VOF (available only if the volume of fluid multiphase model is turned on); DPM (available only for discrete phase simulations with injections defined); and ISAT.

User-Specified   allows you to use the default value (by not selecting the check box), or to specify a value yourself (by selecting the check box and entering a numerical value in the Value field.

Value   allows you to enter a user-specified numerical value for the specific weight.

Dynamic Load Balancing   tab allows you to set load balancing thresholds and intervals.

Physical Models   allows you to set thresholds and intervals for the simulation's physical models.

Threshold   is a percentage and depending on the value, load balancing will occur if the load imbalance is greater than the value entered.

Interval   allows you to specify the desired interval for load balancing cycles, in terms of number of iterations. When a value of 0 is specified, ANSYS FLUENT will internally determine the best value to use, initially using an interval of 25 iterations. You can override this behavior by specifying a non-zero value. ANSYS FLUENT will then attempt to perform load balancing after every N iterations, where N is the specified Balance Interval.

Dynamic Mesh   allows you to setload balancing threshold and interval values for your dynamic mesh. This option is only available when the dynamic mesh model is enabled.

Auto   allows a percentage of interface faces and loads to be automatically traced.

Threshold   is a percentage and depending on the value, load balancing will occur if the load imbalance is greater than the value entered.

Interval   allows you to specify the desired interval for load balancing cycles, in terms of number of iterations. When a value of 0 is specified, ANSYS FLUENT will internally determine the best value to use, initially using an interval of 25 iterations. You can override this behavior by specifying a non-zero value. ANSYS FLUENT will then attempt to perform load balancing after every N iterations, where N is the specified Balance Interval.

Mesh Adaption   allows you to set threshold values for mesh adaption.

Threshold   is a percentage and depending on the value, load balancing will occur if the load imbalance is greater than the value entered.

Zones   contains a list of cell zones. Partitioning will be applied to cells in zones selected from this list.

Registers   contains a list of cell registers that have been created using the adaption tools. You can restrict partitioning to a group of cells by selecting a register containing the cells. See Section  32.5.5 for details.

Print Active Partitions   (parallel solver only) prints the partition ID, number of cells, faces, and interfaces, and the ratio of interfaces to faces for each active partition (see Section  32.5.7 for information about active partitions) in the console window. In addition, it prints the minimum and maximum cell, face, interface, and face-ratio variations.

Print Stored Partitions   (parallel solver only) prints the partition ID, number of cells, faces, and interfaces, and the ratio of interfaces to faces for each stored partition (see Section  32.5.7 for information about stored partitions) in the console window. In addition, it prints the minimum and maximum cell, face, interface, and face-ratio variations.

Print Partitions   (serial solver only) prints the partition ID, number of cells, faces, and interfaces, and the ratio of interfaces to faces for each stored partition in the console window. In addition, it prints the minimum and maximum cell, face, interface, and face-ratio variations.

Set Selected Zones and Registers to Partition ID   allows you to set a value which assigns selected Zones and/or Registers to a specific partition ID. A region or zone is marked before setting the marked cells to one of the partition IDs.

Use Stored Partitions   (parallel solver only) allows you to make the stored cell partitions the active cell partitions. The active cell partition is used for the current calculation, while the stored cell partition (the last partition performed) is used when you save a case file.

Partition   subdivides the mesh into the selected number of partitions using the prescribed method and optimization(s).

Default   sets all controls to their default values, as assigned by ANSYS FLUENT. After execution, the Default button becomes the Reset button.

Reset   resets the fields to their most recently saved values (i.e., the values before Default was selected). After execution, the Reset button becomes the Default button.