A characteristic dynamic mode decomposition

被引:0
作者
Jörn Sesterhenn
Amir Shahirpour
机构
[1] Technical University of Berlin,
[2] Brandenburg University of Technology,undefined
来源
Theoretical and Computational Fluid Dynamics | 2019年 / 33卷
关键词
Turbulent coherent structures; Modal analysis; Dynamic mode decomposition;
D O I
暂无
中图分类号
学科分类号
摘要
Temporal or spatial structures are readily extracted from complex data by modal decompositions like proper orthogonal decomposition (POD) or dynamic mode decomposition (DMD). Subspaces of such decompositions serve as reduced order models and define either spatial structures in time or temporal structures in space. On the contrary, convecting phenomena pose a major problem to those decompositions. A structure traveling with a certain group velocity will be perceived as a plethora of modes in time or space, respectively. This manifests itself for example in poorly decaying singular values when using a POD. The poor decay is counterintuitive, since a single structure is expected to be represented by a few modes. The intuition proves to be correct, and we show that in a properly chosen reference frame along the characteristics defined by the group velocity, a POD or DMD reduces moving structures to a few modes, as expected. Beyond serving as a reduced model, the resulting entity can be used to define a constant or minimally changing structure in turbulent flows. This can be interpreted as an empirical counterpart to exact coherent structures. We present the method and its application to a head vortex of a compressible starting jet.
引用
收藏
页码:281 / 305
页数:24
相关论文
共 52 条
[1]  
Adrian RJ(2007)Hairpin vortex organization in wall turbulence Phys. Fluids 19 041301-54
[2]  
Adrian RJ(2000)Vortex organization in the outer region of the turbulent boundary layer J. Fluid Mech. 422 1-1889
[3]  
Meinhart CD(2013)Streamwise-localized solutions at the onset of turbulence in pipe flow Phys. Rev. Lett. 110 502-81
[4]  
Tomkins CD(1967)Viscous sublayer and adjacent wall region in turbulent pipe flow Phys. Fluids 10 1880-777
[5]  
Avila M(2007)Large- and very-large-scale motions in channel and boundary-layer flows Philos. Trans. R. Soc. Lond. A 365 665-26
[6]  
Mellibovsky F(1990)A general classification of three dimensional flow fields Phys. Fluids A 2 765-664
[7]  
Roland N(2003)Traveling waves in pipe flow Phys. Rev. Lett. 91 502-94
[8]  
Hof B(2005)An objective definition of a vortex J. Fluid Mech. 525 1-378
[9]  
Bakewell HP(2014)The energetic motions in turbulent pipe flow Phys. Fluids 26 125102-589
[10]  
Lumley JL(2011)Visualizing the very-large-scale motions in turbulent pipe flow Phys. Fluids 23 011703-19