Spatio-temporal instabilities in viscoelastic channel flows: The centre mode

doi:10.1016/j.jnnfm.2023.105072

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	Spatio-temporal instabilities in viscoelastic channel flows: The centre mode
	Wan, Dongdong ; Sun, Guangrui ; Xu D(徐多); Zhang, Mengqi ; Shu, Chang
发表期刊	JOURNAL OF NON-NEWTONIAN FLUID MECHANICS
	2023-09-01
卷号	319 页码:105072
ISSN	0377-0257
摘要	We study in this work the spatio-temporal characteristics of the centre-mode linear instability in viscoelastic channel flows of Oldroyd-B and FENE-P fluids. The linear complex Ginzburg-Landau equation derived using an amplitude expansion method is adopted to determine whether the flow is convectively unstable or absolutely unstable. Comparison of the obtained results with those from the conventional saddle-point searching method shows a favourable agreement. This demonstrates the good predictability of the linear complex Ginzburg- Landau equation which is more suitable for a parametric study in a large space than the conventional method. We found that the centre-mode instability in the viscoelastic channel flow is of a convective nature, i.e., the trailing edge of the wavepacket travels downstream. This could be attributed to the relatively high phase speed, low spreading rate and low growth rate of the instability, collectively preventing a disturbance from travelling upstream. Our results show that stronger polymer elasticity (a greater elasticity number or larger polymer concentration) marginally affects the trailing-edge velocity of the centre mode. Decreasing the maximum polymer extensibility in the FENE-P model reduces the spreading rate of the wavepacket and makes the centre-mode disturbance more convective. Theoretical derivations at asymptotically high Reynolds numbers confirm the convective nature of the instabilities from numerical observations. Our results may be conducive to a better understanding of the spatio-temporal instability in viscoelastic experiments.
关键词	Viscoelastic fluids Channel flows Spatio-temporal instability Ginzburg-Landau equation
DOI	10.1016/j.jnnfm.2023.105072
收录类别	SCI ; EI
语种	英语
WOS记录号	WOS:001020747900001
WOS研究方向	Mechanics
WOS类目	Mechanics
项目资助者	China Scholarship Council [201906220200] ; NUS research scholarship ; NUS (Suzhou) Research Institute ; National Natural Science Foundation of China [12202300, 92152106]
论文分区	二类
力学所作者排名	3+
RpAuthor	Zhang, MQ (corresponding author), Natl Univ Singapore, Dept Mech Engn, 9 Engn Dr 1, Singapore 117575, Singapore.
引用统计
文献类型	期刊论文
条目标识符	http://dspace.imech.ac.cn/handle/311007/92573
专题	非线性力学国家重点实验室
作者单位	1.{Wan, Dongdong, Sun, Guangrui, Zhang, Mengqi, Shu, Chang} Natl Univ Singapore, Dept Mech Engn, 9 Engn Dr 1, Singapore 117575, Singapore 2.{Xu, Duo} Chinese Acad Sci, Inst Mech, State Key Lab Nonlinear Mech, Beijing 100190, Peoples R China 3.{Xu, Duo} Univ Chinese Acad Sci, Sch Engn Sci, Beijing 100049, Peoples R China
推荐引用方式 GB/T 7714	Wan, Dongdong,Sun, Guangrui,Xu D,et al. Spatio-temporal instabilities in viscoelastic channel flows: The centre mode[J]. JOURNAL OF NON-NEWTONIAN FLUID MECHANICS,2023,319:105072.
APA	Wan, Dongdong,Sun, Guangrui,徐多,Zhang, Mengqi,&Shu, Chang.(2023).Spatio-temporal instabilities in viscoelastic channel flows: The centre mode.JOURNAL OF NON-NEWTONIAN FLUID MECHANICS,319,105072.
MLA	Wan, Dongdong,et al."Spatio-temporal instabilities in viscoelastic channel flows: The centre mode".JOURNAL OF NON-NEWTONIAN FLUID MECHANICS 319(2023):105072.

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