Review Results for Scenario and Frequency Based Analysis


The remainder of the tutorial will use the Tutorial 11.ifx (27MB) file included in this download - inFlux v2.0 Tutorials 10 - (357MB). This file has the updated data and information but not the data files. The Data Files will have a small warning sign next to them indicating that the file is not found but this can be ignored for this tutorial.

Tutorial 11 - Figure 24 - Showing that the data files for this project will not be included so they will appear with a warning icon which can be ignored for the purposes of this tutorial


With a Risk Data Set defined and simulations complete, risk contours can be created.


Risk contours can show results based on one of the following methods:

  • Scenario - will display results in the contour showing how many cases (scenarios) above the defined LFL value exist on the defined plane. Can also be thought of as a 'heat map' showing where the most cases exist having above the chosen value.

  • Frequency - rather than representing individual cases, the frequency information combined with the wind probably is used to show regions which are most likely to have a gas leak above the defined LFL value

  • Probability - only used with risk-based ventilation simulations such as Helideck Turbulence.

  • Risk - discussed in the next section, risk contours apply a consequence to the leak frequency data, the contour will show the risk of having an exceedance above the defined LFL value.



This section will define a Scenario and a Frequency contour:

  1. Ensure that the Risk Data Set 01 has been updated by right-clicking its name and selecting 'regenerate' if the option is not available then the risk data set is updated.

  2. Select Risk Contour from the Add Items Tab

  3. Leave the Name as its auto-defined one

  4. Select the Risk Data to the one created in the previous section - Risk Data Set 01

  5. Set the Data Type to Scenario

  6. Enter a value of Exceedance as Greater than "10%LFL"

  7. Set the On Plane to XY and enter the Offset as "16 meters"

  8. Leave the Relative To option as Domain

  9. Open the Coloring section and set the Range to be User Defined. Enter a value from "0" to "20" as the Min and Max values, respectively. As the data type was set to scenario this will show regions having more than 20 cases (scenarios) with above 10% LFL in red.

  10. Click the Add Item button



Tutorial 11 - Figure 25 - Added contour showing exceedance of 10% LFL with a scenario basis


In the resulting contour, the highest concentration of scenarios having above 10%LFL exist close to the leak locations. If the contour isn't displayed, ensure it is linked to the contour by right clicking the newly created risk contour and selecting Link to Legend.


Once defined, the contour can be moved to any height or any plane (XY, YZ or ZX) within the Risk Data Set. Click the contour name in the Project Items Tab and change the Plane Offset to "14 meters" in the properties panel.


At a height of 14 meters, just 2 meters lower than before, gives a much different picture than before. Since the leaks were defined at the top of the module most of the gas clouds simulated stayed at a higher elevation. This will not always be the case as there are many factors which affect where gas dispersions travel to.


Tutorial 11 - Figure 26 - Risk Contour moved to a lower elevation showing that not many gas clouds traveled under the top deck


Add a second risk contour to the project, this time using Frequency as the type:

  1. Toggle off the visibility of the risk contour defined above.

  2. Select Risk Contour from the Add Items Tab and leave the Name as its auto-defined one

  3. Select the Risk Data as Risk Data Set 01

  4. Set the Data Type to Frequency. 

  5. Enter a value of Exceedance as Greater than "10%LFL"

  6. Set the On Plane to XY and enter the Offset as "16 meters"

  7. Leave the Relative To option as Domain

  8. Set the Range in the Coloring section to Auto

  9. Click the Add Item button


This frequency contour shown below is the frequency of gas exceeding the defined 10% LFL for the cases simulated. This incorporates both the leak frequency and the wind probability of all simulated cases. For the Jet color maps - red regions will have a high frequency and blue regions have a low frequency. If the legend does not appear or still displays information about the scenario exceedance contour, right click the frequency contour and choose Link to Legend.


Tutorial 11 - Figure 27 - Updated contour showing exceedance of LFL with a frequency basis


The Data Type, exceedance values, plane offsets and defined plane may all be changed via its properties panel after the risk contour has been defined. Note when changing the data type (scenario to frequency or vice versa) the variable range, shown below, should be set to auto defined (Variable Min-Max) to avoid confusion on the units.

Tutorial 11 - Figure 28 - Where to set the Variable Range for a simulation. The max and min values for the Variable and User are listed below the dropdown showing you the values that would be used for each. User Minimum and User Maximum values can be edited


Continue to the next section to define a consequence value to each of the dispersion cases.