Water spray curtains can provide an effective and rapid dilution mechanism for low lying dense clouds.  Frequently such clouds are released as a result of a chemical manufacturing, storage or gas transportation accident.

Extensive field and laboratory tests have been performed to determine how well water curtains can mitigate actual spill conditions.  Numerical methods are often proposed to provide system design or timely response information, but most of these models reduce mathematical and computational complexity by integrating the equations of motion over volumes, sections or depths which provides computational speed but often sacrifices mixing detail and typically presume the use of empirical entrainment relationships.

In this study NIST FDS and Pyrosim have been used to reproduce the water-spray/cold carbon dioxide releases performed during a field experiment by the UK Health and Safety Executive (1981).  Parallel wind tunnel experiments and box and slab models CFD models are also available. Thus, there is an opportunity to provide side-by-side comparisons of field, wind tunnel, box, slab and FDS CFD modeling methods.

Images Gallery

Videos

Short videos of the ground concentrations during a spill situation without water sprays and with water spray curtains.

Without Spray Curtain

With Spray Curtain

A paper, “CFD modeling of water spray interaction with dense gas plumes” presented at the 13^th International Conference of Wind Engineering, Amsterdam, July 2011 contains study details.

To download the new version of Pathfinder, please visit the download page provided when you purchased Pathfinder or register for a free 30-day trial.

This version of Pathfinder uses version 1.6.0_22 of the Java VM.

Changes since Pathfinder 2011.1.1128:

• Pathfinder can now import PSM files created by PyroSim 2012

To download the new version of PyroSim, please visit the download page provided when you purchased PyroSim or register for a free 30-day trial.

This version of PyroSim is designed for FDS version 5.5.3 and Smokeview version 5.6. It uses version 1.6.0_31 of the the Java Runtime Environment.

Changes since PyroSim 2012.1.0423:

• PyroSim will no longer crash when the DT_INSERT parameter contains a null value – an issue in some legacy PSM files.
• Imported DWG/DXF geometry containing degenerate triangles will no longer cause PyroSim to crash during the Convert to Blocks and Preview FDS Blocks operations.

Note: If you downloaded this version prior to May 3, 2012, PyroSim may display an incorrect version number in the about box (PyroSim 2012.1.0417). Installs that report the incorrect version number contain all other updates for PyroSim 2012.1.0430. New installers have been uploaded to fix this issue. To make PyroSim’s about box display correct information, you can uninstall, re-download, and re-install.

To download the new version of PyroSim, please visit the download page provided when you purchased PyroSim or register for a free 30-day trial. Members of the PyroSim mailing list will receive an email containing a summary of changes and a link to the download page.

This version of PyroSim is designed for FDS version 5.5.3 and Smokeview version 5.6. It uses version 1.6.0_31 of the the Java Runtime Environment.

Major changes since PyroSim 2012.1.0312 (beta) include:

• PyroSim now has several new right-click menu options to split, merge, and refine meshes.
• PyroSim now has a graphical tool to split a single mesh into multiple meshes.
• The FDS Simulation dialog is now modeless, allowing the user to stop or cancel a simulation before exiting PyroSim in the event of a crash.
• Gravity can now be specified as a function of time or the x-coordinate.
• Greatly improved PyroSim’s performance when snapping the cursor to geometric objects.
• Added support for particle activation (CTRL_ID and DEVC_ID).
• HVAC name list support can be enabled by installing FDS6 executables and running PyroSim with the flag: -J-DHVAC
• Objects in FDS input files specifying their color as “INVISIBLE” will no longer be imported as opaque.
• Updated the Java Runtime Environment (JRE) shipped with PyroSim to version 1.6.0_31. This fixes a bug that prevented PyroSim from opening files located on MicroSoft Distributed File Systems (MS-DFS).

If you would like to try the beta version of PyroSim 2012, please select the appropriate download link:

PyroSim-2012-1-x86-en-0312.msi – 32-bit Installer

PyroSim-2012-1-x64-en-0312.msi – 64-bit Installer

You can activate the beta using the following online activation key (expires April 30, 2012):

4F60 E98D AE5E 5099 6865 79

Changes since PyroSim 2011.1.1409 include:

• Replaced PyroSim’s DXF import library with the Teigha library. This change made it possible for PyroSim to import DWG files directly without conversion to DXF. DXF files are still supported. Imported 2D geometry can now be “snapped to” with the geometry tools – making it easier to sketch walls and other geometry without relying on PyroSim to convert 2D geometry to walls. Imported 3D geometry is now represented more efficiently and as solid geometry – an improvement over the previous approach could only collect thin, 3DFACE-based geometry.
• The PyroSim actions used to import CAD and FDS files have been merged into a single action.
• Many improvements to PyroSim’s geometry editing features. Highlights include: snapping to grids, objects, and angle constraints; precise keyboard entry; pushing and pulling for object faces; and surface “painting” tools for obstructions and vents. For a complete description, please read the Drawing in PyroSim chapter of the PyroSim Manual.
• Updated the PyroSim manual and example problems.
• When PyroSim crashes due to an unknown error, a dialog will be displayed that helps users submit a report containing detailed data about the crash. The keyboard combination CTRL+ALT+F6 will now artificially induce PyroSim to crash.
• All PyroSim objects can now be grouped in the tree. Grouping was previously limited to geometry.
• When editing a geometric object, it is now possible to change the object’s group within the editor dialog. Previously, this was only possible using the Change Group action.
• The backup file that is created after a PSM file is successfully opened now uses the user’s “home” folder as a fallback if the PSM file folder is not writable. Previously, it used the system’s temp folder. The crash log file writer now also uses this logic.
• PyroSim’s Help menu now contains links to launch installed and online documentation.
• The texture dialog now has better performance with large numbers of textures and the aspect ratio of textures can now be locked when editing size.

Changes since PyroSim 2011.1.1219 include:

• Fixed a bug in PyroSim’s GE1 file writer that caused Smokeview to display geometry from the GE1 file as transparent.

Changes since PyroSim 2011.1.1114 include:

• Support for FDS 6
• Improved tools for drawing and editing geometry
• Support for HVAC network modeling in FDS
• Improved CAD file import, including DWG format files
• Automatic partitioning of meshes for parallel FDS runs
• Standalone FDS run manager

We will also be incorporating bug fixes and improving some existing features as we work on the new version.  If you have any suggestions or feature requests, please send them to support@thunderheadeng.com.  We have also started a site where users can add ideas and vote on other suggestions — http://thunderheadeng.ideascale.com.  This site is just getting started, so please stop by and add your suggestions.

Because the CSV file writer was locale-sensitive but the reader was not, commas in the time column of both CSV files could be incorrectly interpreted as a column break and incorrect data could be displayed in Pathfinder’s 2D results.

This fix forces the CSV file writer to use an English locale when creating the file. Any existing CSV files that were affected will still contain the error. To repair output files, these simulations must be re-run. Alternately, the CSV output files can be manually repaired.

Changes since PyroSim 2011.1.1103 include:

• Fixed a bug that caused certain rotations of axis-aligned blocks (obstructions and holes) to be internally converted to shells – causing problems with hole-cutting and conversion to blocks.
• Fixed a bug with DXF import that caused triangles to be skipped if they used a 4-point definition and the first two points were identical. Previously, only the last two points were coalesced.