Many important industrial devices involve circular or annular fluid systems consisting of many identical units symmetrically arranged in a circle or ring shape, for example, gas-stove ring burners, turbomachine rotors, can-annular combustors in gas-turbine engines, and Chevron-type primary exhaust nozzles for aircraft engines.

   The N-periodic systems of flickering buoyant diffusion flames, as simplified prototypes of flame oscillators in annular combustors, are studied to experimentally observe collective dynamical modes, computationally reproduce major modes, and theoretically establish a predictive vortex-dynamical model.

    The relevant works have been published in Physical Review Fluids, Proceedings of the Combustion Institute, Combustion and Flame (under review)

Single Flickering Buoyant Diffusion Flame

Dual Flickering Flames

In-phase

Anti-phase

Independent

Recent Progress on Torsional Anharmonicity of Large Molecules in Partition Function Calculation Using the Metric-based Multi-Structural Method

      Calculating partition function plays an important role in the high-level chemical kinetics of large molecules, in which the conformational torsional anharmonicity needs to be correctly treated. The multi-structural approximation with the torsional anharmonicity (MS-T) method proposed by Truhlar and his collaborators has been widely used. Regardless of the noticeable success of the MS method and its variants, some questions about the implementation of these methods need to be answered. First, whether we need a complete set of distinguishable torsional conformers? Second, how to find an appropriately chosen small subset of distinguishable torsional conformers which can significantly reduce the computational cost while retaining acceptable accuracy? Last and more important, how to find a general approach to assess the performance of various subsets?

     The recent work aimed to propose a systematic method to assess and explain the performance of various variants of the MS-T method. It is worth emphasizing that the proposed method provides a mathematically rigorous and computationally effective diagnostic tool to assess various MS-T methods dealing with the torsional anharmonicity of large molecules in partition function calculation. The work, “A Metric-based Assessment Method for MS-T Formalism with Small Subsets of Torsional Conformers”, has been published in The Journal of Physical Chemistry A, DOI: 10.1021/acs.jpca.2c04724