Questions And Answers: BOSfluids Integration With Caesar II

Does BOSfluids handle two-phase flow phenomena, like line clean-out/purging with pressurized gas or the filling of a water deluge (fire) system?
BOSfluids has support for flood and drain analyses. These analyses assume that the flooding or draining happens sufficiently fast that the liquid/air interface can be assumed to be perpendicular to the piping axis, and there is no mixing of the two phases. The deluge nozzle element models the interaction/connection with the atmosphere or another large volume of gas. Depending on the state of the piping and atmosphere, the deluge nozzle takes gas or expels air. This allows you to simulate the clean-out of the system via pressurized gas or the rapid filling of a deluge fire water system.
Is the interface/integration between BOSfluids and pipe stress packages (like Caesar II) bi-directional? I.e. can changes be made in either the pipe stress package or BOSfluids, and those changes be communicated to the other program?
The interaction of BOSfluids with pipe stress packages, like CAESAR II, is unidirectional. The integration is achieved through the importing of a Caesar II neutral file into BOSfluids, where the fluid flow model is then added/completed. In the other direction, BOSfluids exports “time history force” files that are then imported into the pipe stress program to perform a more complete dynamic analysis of the piping system, with the fluid-related forces are also taken into account. BOSfluids does support updating a model’s geometry based on an external model. For example, if you make changes in CAESAR II, you can export the CAESAR II model to a neutral file. This neutral file can be imported into BOSfluids with the option to update only the model’s geometry, keeping your boundary conditions and other flow-specific properties that were previously defined in BOSfluids. This allows you to update the BOSfluids model with the changes made in CAESAR II without the need to redefine your flow scenarios. You can also add to, or extend an existing BOSfluids model by importing multiple Caesar II neutral files that represent different piping sections. The integration between BOSfluids and pipe stress programs is represented in the drawings below.
Are the forces that are exported from BOSfluids exported as distributed loads or as concentrated/point loads?

BOSfluids export the forces as concentrated loads on the end nodes of bend pairs i.e. force
pairs. BOSfluids calculates the unbalanced force for the whole pipe section between two
bend pairs.

How are the forces from BOSfluids exported to other pipe stress programs? (i.e. other than Caesar II?)
The process is similar for the supported packages. The forces are exported to a file format that can be read by the 3rd party pipe stress package. We currently support exporting forces in the following formats:
• Caesar II (Setup Tables, or _7 Files)
• Caesar II (Caesar II FRC Files)
• Bentley AutoPipe (“.thl” files)
• Text Data Files
• CSV file (spreadsheet)
If you have a pipe stress program that expects or needs force time history data in a format that is not supported, please contact us with the details and we will look into adding a new format.
Does BOSfluids model and analyze flow pulsations and induced vibrations? (AIV/FIV)
BOSfluids is aimed at non-periodic transient phenomena, like water hammer and surge analysis. Dynaflow Research Group has developed a separate software product, BOSpulse, specifically to model and analyze periodic flow phenomena and the resulting pulsation. For those interested in these phenomena, I would highly recommend the webinar about BOSpulse will be presented later this year. More information on BOSpulse can also be viewed on our website at this URL:
Is BOS B31 similar to BOSfluids? What are the differences between these two programs?
BOSfluids and BOS B31 are significantly different products. BOSfluids is used for analysis of transient flow phenomena, like pressure surges, in pipeline systems. BOS B31 is a simplified utility program that was designed and built to give pipe stress engineers a quick way to check if a piping system is susceptible to acoustic induced vibrations (AIV). BOS B31 is a tool that can be used to quickly determine whether or not a more in-depth AIV analysis of the system is required. BOSfluids is a detailed, general fluid flow modeling and analysis product that can be used to quickly model simple piping segments, but also large, complex piping and pressure vessel designs, with complex flow conditions throughout.
Does BOSfluids support the calculation of slug flow forces?
Yes. BOSfluids flood and drain analysis type can be used to model slug hammers in partially filled systems. However, if the pipe flow is in a slug regime, then you should use empirical relations to determine the slug forces and their frequency.
Yes. BOSfluids flood and drain analysis type can be used to model slug hammers in partially filled systems. However, if the pipe flow is in a slug regime, then you should use empirical relations to determine the slug forces and their frequency.
Do you have an integration with Bentley’s AutoPipe program?
Yes. BOSfluids can import a Bentley AutoPipe model that has been exported from AutoPipe as a Caesar II neutral file. BOSpulse also supports exporting calculated time history force pairs in a format that can be imported by AutoPipe, as discussed above.
Does BOSpulse only support importing model data using the Caesar II neutral file format?
No. BOSfluids also supports importing model data in these other formats:
• CAESAR II structural files (for structural components)
• Piping Component Format (PCF) files
• Pipe Profile files
• EPANET files
• BOSpulse model files.

BOSfluids integration with Caesar II and other pipe stress programs