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dirk April 25, 2005 08:39

LES of jet in cross flow

I am currently doing a simulation of a jet in cross flow with the RNG based SGS model. The oncoming boundary layer should be laminar, so my inlet BC some diameters upstream of the injection hole is a laminar velocity profile with free stream velocity of 5.5 m/s and turbulence intensity 0.25%. When I used the SL model, the flow developed turbulent so I changed to RNG as it is said to model transitional effects. But in the whole domain the SGS turbulent viscosity is zero since the maximum of the ramp function x (equation 10.7.13 in Fluent 6.0 manual) is around -98. So, in my opinion, I am doing a completely laminar simulation, which would mean DNS.

I compared the resolution of my grid with other works in literature and it is similar. The jet Reynolds number based on maximum jet velocity and hole diameter (8mm) is 1050, blowing ratio is around 0.4. My maximum cell extent around the hole is 0.75mm, y+ below 0.7, and time step size is 0.1ms.

Now I am wondering if it is correct what I am doing. I am thankful for every comment. Maybe someone has experience with the new SGS models in Fluent 6.2 and can recommend one of them.

Thanks in advance, Dirk

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