[velkon]

Hi all,
How can you determine the turbulent Prandtl number and the turbulent Schmidt number for a premixed lean hydrogen combustion? Or would you for a simulation just give the values for the fuel in this case hydrogen as turbulent Prandtl and turbulent Schmidt number? I will be using a Dynamic Structure LES model

[LuckyTran]

turbulent Prandtl number and Schmidt numbers are phenomenological flow properties. They are not material properties. It doesn't matter whether it is fuel, oxidizer. They're not related to the material. It depends on the flow.

How to determine it in general? Do DNS or measure it using really complicated techniques. It's not trivial. Most people just use the defaults.


The question you are asking is akin to how to specify a turbulent viscosity... Tons of turbulence models have been developed for this purpose that involve solving additional transport equations with their own calibrated constants. Now someone needs to do it again for turbulent Prandtl and Schmidt numbers.

[bigfootedrockmidget]

I'd check some recent papers where they either do simulations that are very similar to what you are doing, or where they compute the turbulent Schmidt number with a detailed chemistry approach. I've seen Sct=0.3 for hydrogen flames, but you'd better make sure that your value is backed up by some literature because you do not want to redo a reacting LES computation.

[reneamcmahangm1410]

Originally Posted by velkon

Hi all,
How can you determine the turbulent Prandtl number and the turbulent Schmidt number for a premixed lean hydrogen combustion? Or would you for a simulation just give the values for the fuel in this case hydrogen as turbulent Prandtl and turbulent Schmidt number? I will be using a Dynamic Structure LES model

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