I am trying to develop a model for partially-premixed stratified combustion in ANSYS Fluent, which will have 3 separate streams with different equivalence ratios. I know that the 'secondary stream' can be enabled from the 'stream options' in 'species model' section. However, I cannot find the option to add a third fuel-oxidizer stream. How should I set the third stream? Also, if all the streams have the same inlet bulk/throat velocity (say 10m/s), how can I calculate the laminar flame speed? The laminar flame speed has to be defined in the material (pdf-mixture) section.