Large eddy simulations of 45° and 60° inclined dense jets with bottom impact
2017
Zhang, Shuai | Law, Adrian Wing-Keung | Jiang, Mingtao
In the present study, we performed a numerical study with the Large Eddy Simulations (LES) approach to simulate inclined dense jets with 45° and 60° inclinations in a stagnant ambient, including the bottom impact and subsequent spreading on the wall boundary. The objective was to evaluate the performance of LES on the predictions of both the kinematic and mixing behavior of the inclined dense jet with bottom boundary in the near field region. The Dynamic Smagorinsky sub-grid model was adopted with near-wall modeling for the bottom boundary. The results showed that LES can reasonably predict the jet trajectory with the present mesh scheme, including the locations of the return point and impact point at the boundary. The localized concentration build-up at the impact point reported by Abessi and Roberts (2015) was also reproduced. The impact dilution was however underestimated by ∼20% in general corresponding to the grid resolution adopted in the present study, which demonstrated the challenge to simulate accurately the dynamics of the mixing behaviour as well as the wall interaction processes. The spreading layer was examined to the end of the near field region as defined by Roberts et al. (1997). The profiles of the mean concentration and concentration fluctuation along the spreading layer were found to be similar to previous experimental results with self-similar behaviour. The dilution was however also under-predicted within the spreading layer.
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