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Now click on the Species option and change it from Off to "Partially Premixed Combustion". In the Chemistry tab, change the Fuel Stream Rich Flammability Limit to 1. Changing this value means that FLUENT will perform equilibrium calculations at all mixture fractions (1.0 being the largest possible fraction). If this was not the case, the composition would be computed based on mixing instead, for fractions above the specified limit.

Click on the Boundary tab. Enter the values as shown in the following image. These values correspond to CH4 (methane) and air (nitrogen and oxygen) injected at a lean (less than 1.0) equivalence ratio of Φ = 0.8, representing the premixed fuel at T=300K. This ratio is defined as the ratio of the fuel to oxidizer ratio, to the fuel to oxidizer ratio at stoichiometric conditions. In addition, oxidizer (air) will be injected as a co-flow outside of the fuel stream, at 650K. To add other species to the boundary, you would select the species you want and click "Add" under the Boundary Species options in this tab.

Ignore the Control and Flamelet tabs, and select the Table tab. Click "Calculate PDF Table" to generate the pre-computed PDF table denoting mixture fractions that will handle the non-premixed combustion analysis. Investigate PDF table parameters and dependencies by clicking on "Display PDF Table", selecting desired options, and clicking "Display.

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