Adding an Isosurface of Incident Radiation

Radiation travels in all directions so a isosurface is generally helpful in viewing this variable although viewing the result on a 2D contour can be beneficial in some applications.

 

It should be noted that the Incident Radiation variable should be used to assess the human impact of the fire, i.e. radiation someone would expiereince when standing at a certain point in the domain. This variable can be affected by solar radiation, which can be added with this feature. For radiation on structures and surfaces, monitor surfaces should be used.

 

This section will add two isosurfaces of different incident radiation values. 

  1. Click the Add Item tab and select Isosurface from the dropdown menu.

  2. Select Pure Methane 100MW on Westerly, 5m/s as the Simulation.

  3. Set the Variable to Incident Radiation, kW/m2. Upon selection the min and max values of the case will be displayed next to the value textbox.

  4. Enter a value of "100" as the Value.

  5. Set the Color to be Red by selecting the red swatch () from the available color palette dropdown menu.

  6. Click the Add Item button

  7. Staying in the Add Item Tab, change the Variable to 10 kW/m2 and set the Color to a transparent orange using the advanced option of the color palette menu.

  8. Click the Add Item button to add the second isosurface to the project

 

Your window should now be similar to the below figure showing the two radiation values for the single jet fire case. 

 

Tutorial 15 - Figure 09 - two isosurfaces defined for incident radiation, red representing 100kW/m2 and orange as 10kW/m2

 

 

From the properties panel of each isosurface the value which it displays can be changed. Select the 100kW/m2 isosurface and change the Value to 80. We can determine that this walkway would most likely be blocked if this event were to occur. For reference, 80 kW/m2 is when uncovered human skin will receive second degree burns instantly, 10kW/m2 will give second degree burn in around ten seconds (per NIST). API 521, section 5.7.2.1 also provides information on thermal radiation effect on humans. ***. 800°C is an estimate to the size of the flame.***

 

Continue to the next section to another isosurface for the soot volume fraction.