Restarting a solution using the serial flow solver

The serial flow solver uses the data in the following files for a restart:

• flow.gem

• flow.fli

• flow.bfi

• flow.prp

• flow.csc

• flow.mgd

• flow.ent

Supported modifications to the model

You can make some modifications to your model and still perform a restart using a previous analysis.

You can change:

• Flow boundary condition values and options

• Solver attributes and parameters

You cannot change:

• The geometry

• The mesh

• Modeling objects

The serial flow solver has special rules concerning modifications of Inlet Flow, Outlet Flow, and Internal Fan type Flow Boundary Conditions (flow BCs) before a restart. These are the only objects that you can remove from the model prior to a restart. Once a flow BC has been removed, you cannot reactivate it and perform a restart afterwards. Special rules also apply to flow BCs defined with fan curves. Only a flow BC initially defined with a fan curve can be restarted using a fan curve. However, existing fan curves can be redefined or removed prior to a restart.

Example:

To calculate different friction scenarios, you can change the roughness of a Flow Surface simulation object, but you cannot add or remove a Flow Surface.

Similarly, to test for an increase in temperature, you can change the inlet temperature or head loss of an opening. You cannot change the region where the opening is located.

Restarting the serial flow solver after a crash

The serial flow solver checks for specific files in the specified directory. By default, backup files (flow.bf1.bak and flow.fl1.bak or flow.bf2.bak and flow.fl2.bak) are written every 25 iterations. When one set of backup files is written, the previous set is deleted. All backup files are deleted when the analysis is completed or if it is paused with the Stop command in the Solution Monitor.

If the analysis has stopped and backup files exist in the run directory, it indicates that the analysis did not terminate normally. Select the Perform Restart check box on the Restart page in the Solution dialog box to restart the analysis using the backup files.

You can control the frequency at which the backup files are written by creating a file named user.prm in the run directory and adding the following line to it:

SAVE_EVERY = [number of iterations]

How do I

Continue a transient solution

Restart a steady state solution

Reuse thermal solution data in a modified or different solution

Learn more

Restarting a solution using the thermal solver

Restarting a solution using the parallel flow solver

Solving the model

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Restarting a solution using the serial flow solver, Simcenter 3D 2021.1 Series

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