Flownex Version 9.0.4 delivers a suite of major and minor enhancements that significantly advance the robustness and usability of its 1D simulation environment. Notable developments include dedicated Nuclear Reactor Components, the implementation of the Henry-Fauske Critical Two-Phase Flow model, extended Metadata functionality and an advanced Convergence Residual Plot for steady state simulations.
Flownex Version 9.0.4 delivers a suite of major and minor enhancements that significantly advance the robustness and usability of its 1D simulation environment. Notable developments include dedicated Nuclear Reactor Components, the implementation of the Henry-Fauske Critical Two-Phase Flow model, extended Metadata functionality and an advanced Convergence Residual Plot for steady state simulations.
The complete Release Notes containing detailed descriptions of the enhancements in the Flownex SE Release 3 version 9.0.4 are available under the Help ribbon in the latest Flownex SE release.
A new Pebble Bed Reactor component has been added that allows a pebble bed reactor to be modelled more easily than using the reactor scripts from the previous Flownex version.
As part of this upgrade the old Pebble Bed Reactor component has been removed and the Nuclear Reactor component has been moved to a Legacy category. The geometry chart used for the new Pebble Bed Reactor has been streamlined and a point neutronics chart has been added to use in conjunction with the built-in component.
A Pressurized Water Reactor (PWR) component has been added to the Nuclear library as shown in Figure 1. The PWR is set up in the same manner as the Pebble Bed Reactor and uses both a geometry chart and a point kinetics chart. The reactor component allows for specifying the fuel element and control rod geometry and generates a network that includes fuel elements and coolant flow paths. A representative fuel element consists of a central fuel region, a gas gap, and cladding, whereas a representative control rod consists of central rod material, a fluid gap and the control rod guide tube.
The PWR leverages the existing point kinetic neutronics model that is extended to allow for the use of the water density in the moderator reactivity feedback. The power calculated by the point kinetic model is distributed in the core based on a specified power distribution and assigned to the solid nodes in the representative fuel element in each zone.
The previous generation of nuclear components have been moved to Legacy categories. This has been done for both the components and the charts, as shown in Figure 2.
There are a variety of critical two-phase flow applications where the flow does not adhere to equilibrium conditions such as pressurized water released through a valve or in pipe burst accidents involving the transport of pressurized water. Applying equilibrium modelling principles to these applications may result in a severe underprediction or overprediction of critical mass flow rates. The Henry-Fauske model is a well-known benchmark for the calculation of critical two-phase flow associated with short tube break cavitating flow as it accounts for the delay in mass and heat transfer in the choking plane.
An option has been added to the Restrictor with Discharge Coefficient, Restrictor with Loss Coefficient and Secondary Loss component to specifically apply the Henry-Fauske frozen model instead of the conventional homogenous equilibrium approach. The option is available for two-phase fluid types when selecting the “Specify advanced inputs” option as shown in Figure 3.
The capability has been added to specify metadata for several different items. These items include components, charts, compounds, and component defaults. The capability to add metadata provides users with a place to store relevant data for an item, for example drawings, calculations, notes etc. The option to add metadata is available within the context menu of an item and can be accessed when right-clicking on the item:
Within the Metadata Editor window, metadata can be added in the form of Text files, Word documents, Excel files, PDF files or images as shown in Figure 5.
The “Add File” option can be used to add existing files and the “New” option can be used to add new blank files. The “Explore” option will open the location of the Metadata. Metadata is copied and exported with the items that they are associated with.
A Residuals plot has been added as a tab on the Flow Solver output window where the residuals are plotted as the network solves, as shown in Figure 6.
The Residuals plot is always active for steady state simulations and can optionally be enabled for transient simulations too. An option is also available to save the data to have the data available in a new session. It is however important to note that saving the data might take up a lot of disk space, especially in transient.
Flownex projects can now be saved as a “.projz” file. This is a zipped file containing the entire project folder.
When opening a “.projz” file, the file will be extracted temporarily into the same directory as the location of the “.projz” file. Upon saving, the project will be saved to this extracted project folder and then zipped into the “.projz” file. When the project is closed the temporary folder will be deleted.
The user can at any stage switch between using the traditional “.proj” file type for a project or the new “.projz” by saving the project as the specific file type.
When creating a new project, the option to save the project as a “.projz” option is available, but the default type is “.proj”.
The capability has been implemented to copy scenarios and actions from a Flownex project to a different instance of Flownex.
If the target does not exist in the project in which the action or scenario has been pasted, the target field will appear red, as shown in Figure 8.
A critical warning during a transient simulation will also be issued if an action with a non-existing target is started, as shown in Figure 9.
The Flow Solver component icons have been updated to enhance visual consistency and clarity across the interface. The previous icons varied in perspective and image quality, leading to a less cohesive user experience. The new icons feature a consistent isometric style, providing a more professional and modern look while remaining recognisable to long-time users.
These updates improve the overall visual language of Flownex SE, especially in complex models where quick identification of components is key.
Some of the component categories contained components which were compound components, which has been converted to built-in components. This should reduce the memory use by projects that contain many of these components and will also speed up the project loading and saving times. The compound components within the following categories have been updated to built-in components:
The following enhancements have been made to the Miller Valves:
The following enhancements has been made to the Idelchik Inlets:
A Conduction Grading Factor input has been added to the Conduction component inputs, as seen in Figure 12.
A Convection Grading Factor input has been added to the Convection component inputs, as seen in Figure 13.
The capability has been added to connect a Convection component between a solid Node and a Boundary Condition. This allows for the modelling of natural convection on the outside of solid structures.
The convection options are limited to natural convection correlations similar to the options available a Composite Heat Transfer component when using the ambient heat transfer option.
Options have been added to the Push Button to turn solving on or off for all components on a specified page:
The following shortcut keys have been added:
An enhancement has been made to Lock or Unlock a shared or external database by setting a password. This will help to ensure that components within a shared database cannot be modified by any user that has access to the database without the password to modify the components within the shared database.
The GIS Importer has been updated to make provision when importing shape files with duplicate lines and lines with zero length.
The 6 Sigma Link coupling has been updated to make provision for a new double type used in Reality DC 2025.
An input has been added where the heartbeat grace period can be adjusted. This is a periodic check done by the Reality DC API to see if the co-simulation is still running. This setting allows it to be extended when needed.
The Revit Network Builder will now also support Revit 2026.
The config file for R1234yf has been added in the Configuration folder in the Flownex installation folder.
A SaveProjectAs function has been added to the API. Additionally, the capability has been added to modify project settings through the API.
The Verification Runner now uses gRPC to run the verification tests. The biggest advantage is that it now also automatically uses the FlownexSE.exe located in the Verification Runner executable folder when running the GUI version tests.
The Verification Results report now includes the date that the tests were completed and the time started and time completed is reported in a 24-hour format.
Flownex SE now includes an updated Ansys Mechanical ACT extension with support for ANSYS 2025 R2. This ensures continued compatibility for integrated workflows between Flownex and the latest version of ANSYS Mechanical.
