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| Title | Speaker |
|---|---|
| Large-eddy simulation of a turbulent boundary layer with passive scalar transport | Qiang Li |
| Location | Time and Date |
|---|---|
| PDC seminar room, Teknikringen 14, level 3 | 14.30-15.30, 2011-05-25 (Wed) |
| Abstract |
|---|
|
A spatially developing turbulent boundary layer over a flat plate under zero pressure
gradient (ZPG) with three passive scalars has been carried out via well-resolved
large-eddy simulation (LES) up to a relatively high Reynolds number Re_\theta=2500 based
on the free-stream velocity U_\infty and momentum-loss thickness \theta. The molecular
Prandtl numbers are 0.2, 0.71 and 2. The laminar inflow is located at Re_\theta = 180
and laminar-turbulent transition is induced by a trip forcing as in the experiments. A
number of turbulence statistics for both flow and scalar fields are obtained and
compared with the previous DNS data and experiments, in general the agreement is
satisfactory. Spectral information is obtained from temporal signals recorded at
different downstream positions. It is observed that the Prandtl number has a strong
influence on the outer layer structures and a stronger outer peak is found for lower Pr
flow case.
Recent DNS by Wu & Moin (2010) showed a monotonically increasing wall limiting behaviour of the turbulent Prandtl number. In addition, Wu & Moin (2009,2010) reported a dominance of hairpin vortices in a zero-pressure gradient turbulent boundary layers in the fully turbulent region. However, in the present simulation, different conclusions are drawn and comments on these issues will be made. |
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