It is well known that the vorticity ω = △× u, where u is fluid velocity, has clear mathematic definition, but for vis- cous flow the definition of a vortex remains an open prob- lem for long [1,2], which has no...It is well known that the vorticity ω = △× u, where u is fluid velocity, has clear mathematic definition, but for vis- cous flow the definition of a vortex remains an open prob- lem for long [1,2], which has now evolved to a big confusion after many ＂vortex identification criteria＂ （＂vortex criteria＂ for short） were proposed to identify various turbulent coher- ent structures observed experimentally and numerically. The present communication attempts to clarify this confusing situ- ation and provide a preliminary answer to the question： What is a vortex？1）展开更多
Vortices,which appear as swirling behaviour of a flow field,are an important phenomenon in fluid dynamics,and the extraction of vortex cores is necessary for the research of vortex evolution in many areas of fluid mec...Vortices,which appear as swirling behaviour of a flow field,are an important phenomenon in fluid dynamics,and the extraction of vortex cores is necessary for the research of vortex evolution in many areas of fluid mechanics.The Liutex method is a milestone in vortex identification and provides a reasonable mathematical definition for a vortex core.Based on this definition,a novel integration-based method is presented,which can reduce the numerical error in the integration process through location optimization.Two typical test cases,the wake vortices of an A320 in the near-ground stage and a helicopter rotor,are examined to show that the proposed method can extract continuous vortex core lines with accuracy and efficiency for vortex parameter study.展开更多
文摘It is well known that the vorticity ω = △× u, where u is fluid velocity, has clear mathematic definition, but for vis- cous flow the definition of a vortex remains an open prob- lem for long [1,2], which has now evolved to a big confusion after many ＂vortex identification criteria＂ （＂vortex criteria＂ for short） were proposed to identify various turbulent coher- ent structures observed experimentally and numerically. The present communication attempts to clarify this confusing situ- ation and provide a preliminary answer to the question： What is a vortex？1）
基金Project supported by the National Natural Science Foundation of China(Grant Nos.U173320010,11802328).
文摘Vortices,which appear as swirling behaviour of a flow field,are an important phenomenon in fluid dynamics,and the extraction of vortex cores is necessary for the research of vortex evolution in many areas of fluid mechanics.The Liutex method is a milestone in vortex identification and provides a reasonable mathematical definition for a vortex core.Based on this definition,a novel integration-based method is presented,which can reduce the numerical error in the integration process through location optimization.Two typical test cases,the wake vortices of an A320 in the near-ground stage and a helicopter rotor,are examined to show that the proposed method can extract continuous vortex core lines with accuracy and efficiency for vortex parameter study.
