Adding an Inflow


Six types of inflows can be added to an in:Flux project, the latter three affect ventilation simulation and can be used for internal ventilation studies:

  • High Pressure Gas Leak - upstream pressure, upstream temperature, hole size, and discharge coefficient are needed as inputs

  • Custom Gas Emission - velocity, temperature, hole size and shape are inputs

  • Group - a collection of multiple leaks combined together to be calculated together as a single inflow.

  • Forced Inlet - a fan that forces air into the system at a specified flow rate

  • Forced Outlet - a fan that forces air out of the system at a specified flow rate

  • HVAC: Through-Flow Fan - the flow rate in m3/s and the characteristics of the fan size and shape are inputs.


In in:Flux, releases can be pointed in any direction: pointing into the wind, away from the wind, off axis, and even directly pointed towards equipment or the ground. For this tutorial we will be adding a high pressure leak pointing at a perpendicular to the wind simulation that was calculated in Tutorial 1.


  1. Click the Add Item tab and select Gas Leak or Emission from the dropdown menu.

  2. Set the Type as High Pressure Gas Leak

  3. Leave the name as "HP Release 01". in:Flux will automatically recognize and increment the naming convention you use, e.g. HP Release 01 will increment to HP Release 02 once the first has been added to the project. More about the automatic naming is described in the Advanced Capabilities section.

  4. Set the Gas to METHANE from the dropdown menu. Here you can select varying pure gases from the DIPPR database, or click the database icon and create your own gas mixture, which will be discussed later in Tutorial 7.

  5. Leave the Upstream Pressure set to "10" bar(g). Note that you can click the bar(g) text to select other units, e.g. atm, bar(a), Pa, and psi as shown in the figure below.


    Tutorial 2 - Figure 02 - Selection of varying units for the upstream pressure in a HP leak definition


  6. For methane gas, enter a value of "10" C for the Upstream Temperature

  7. Leave the Discharge Coefficient as "0.8".

  8. Enter a value of "50" mm as the Diameter. Here you may also enter the flow rate (in kg/s or kg/hr) of the leak rather than the diameter of the hole size, either may be used.

  9. For the Location, click the pick tool button next to the x, y, and z coordinate text boxes as indicated below. This will activate the Point Pick Tool for choosing a location for the leak and freeze the movement of the 3D window. A yellow crosshair icon will follow your mouse pointer with displayed coordinates of the current position. Press Ctrl to pause or suspend the pick tool (this is a toggled option) so that you may move the 3D window without selecting a point. Position your screen to be similar to Figure 03 below. 


    Tutorial 2 - Figure 03 - Suspended Pick Tool in the 3D window to allow for pan, rotate, and zoom without selecting a point.



  10. Zoom into the flange coming out of the top of the tank in the middle of Figure 03, press Ctrl again to toggle off the suspension of the pick tool and select a point on the flange on its northern edge as shown in Figure 04 and Figure 05 below.

    1. Alternatively, you may enter "-6.6, 22.95, 5.94" as the x, y, and z coordinates of the leak location. The entered coordinate may be slightly different from the values obtained from the pick tool, this tutorial will use the values shown in Figure 04 below.

  11. If the pick tool is used for choosing a coordinate of the leak, the normal vector of the chosen point is automatically entered as the Angle from North value with an accuracy equivalent to the Pick Tool Rounding. If the coordinate is entered manually, then you will need to manually enter the orientation for the leak. Regardless of your method of entry, ensure that the Angle from North set as "0" and Elevation as "0" before continuing.


    Tutorial 2 - Figure 04 - Zoomed into location for the high pressure leak.


    Tutorial 2 - Figure 05 - Closer view of leak location with labeled coordinate


  12. Click the Preview checkbox at the bottom left of the screen. A truncated cone with an arrow should be visible, as in the picture below.


    Tutorial 2 - Figure 06 - Preview of the high pressure leak.


  13. Click the Add Item button.


The leak icon should now appear green in color, as in Figure 07 below, and will have been added to the Project Items tab under the Inflows -> Gas Leaks and Exhausts header. Proceed to the next section for setting up and running a dispersion simulation.


Tutorial 2 - Figure 07 - Addition of HP Release 01 to the Project Items tab, changing from a red item (previewed) to a green item (added to the project).