Numerical simulation of two-dimensional unsteady Giesekus flow over a circular cylinder

Peng, Sai1,2; Li, Jia-yu1,2; Xiong, Yong-liang3; Xu, Xiao-yang4; Yu, Peng1,2,5

2021-08-01

10.1016/j.jnnfm.2021.104571

JOURNAL OF NON-NEWTONIAN FLUID MECHANICS   影响因子和分区

0377-0257

1873-2631

This study numerically examines vortex shedding of two-dimensional viscoelastic flow over a circular cylinder at a Reynolds number of 100. The Giesekus model is selected to describe the viscoelastic constitutive relationship and investigate the combined effects of shear-thinning and elasticity. Log-conformation reformulation is employed to stabilize our numerical simulations. The parameters of the Giesekus model considered herein include the Weissenberg number (Wi) ranged from 0 to 80, the mobility factor (alpha) ranged from 0 to 0.5, and the viscosity ratio (beta) fixed at 0.1 and 0.9. The combined effects of shear-thinning and elasticity on flow characteristics and macro parameters such as time-averaged drag coefficient ((C-d) over bar) root mean square of lift coefficient (C-lrms) and Strouhal number (St) are systematically discussed. Shear-thinning triggers an inertial instability by decreasing the apparent viscosity near the cylindrical wall. Elasticity introduces the extensional viscosity in the wake field to suppress flow instability. The combination of these two effects results in an elongation in the recirculating wake and a decrease in both C-lrms and St, which are opposite to those solely induced by shear-thinning. Moreover, the simulation results indicate that strong elasticity may also trigger an elastic instability characterised with very high flow fluctuation at the leading edge of the cylinder, which is unlike the inertial instability caused by shear-thinning. Additionally, strong elasticity or strong shear-thinning increases the drag. But weak elasticity can increase the drag-reduction effect of shear-thinning solutions. The present numerical method associated with the Giesekus model can capture all the typical flow behaviors of a viscoelastic fluid flow past a cylinder revealed by previous experimental results.

Viscoelastic fluid Giesekus model Flow past a cylinder Shear-thinning Flow instability Drag reduction

SCI ; EI

英语

第一 ; 通讯

National Natural Science Foundation of China (NSFC)[11872187,11672124] ; Guangdong Provincial Key Laboratory of Turbulence Research and Applications[2019B21203001] ; Shenzhen Key Laboratory of Complex Aerospace Flows[ZDSYS201802081843517] ; Shenzhen Science and Technology Innovation Commission[JCYJ20180504165704491] ; National Natural Science Foundation of China[12071367] ; Shaanxi Youth Top-notch Talent Program[289890259] ; Shaanxi Youth New Star Program of Science and Technology[2019KJXX-012]

Mechanics

Mechanics

WOS:000672521100001

ELSEVIER

20212510528821

Circular cylinders ; Drag ; Elasticity ; Non Newtonian flow ; Numerical methods ; Numerical models ; Reynolds number ; Shear thinning ; Stability ; Steady flow ; Viscoelasticity ; Wakes

Fluid Flow, General:631.1 ; Mathematics:921 ; Numerical Methods:921.6 ; Physical Properties of Gases, Liquids and Solids:931.2

ENGINEERING

Web of Science

1.Southern Univ Sci & Technol, Dept Mech & Aerosp Engn, Shenzhen Key Lab Complex Aerosp Flows, Shenzhen 518055, Peoples R China
2.Southern Univ Sci & Technol, Guangdong Prov Key Lab Turbulence Res & Applicat, Shenzhen 518055, Peoples R China
3.Huazhong Univ Sci & Technol HUST, Dept Mech, Wuhan 430074, Peoples R China
4.Xian Univ Sci & Technol, Sch Comp Sci & Technol, Xian 710054, Peoples R China
5.Southern Univ Sci & Technol, Ctr Complex Flows & Soft Matter Res, Shenzhen 518055, Peoples R China

Peng, Sai,Li, Jia-yu,Xiong, Yong-liang,et al. Numerical simulation of two-dimensional unsteady Giesekus flow over a circular cylinder[J]. JOURNAL OF NON-NEWTONIAN FLUID MECHANICS,2021,294.

Peng, Sai,Li, Jia-yu,Xiong, Yong-liang,Xu, Xiao-yang,&Yu, Peng.(2021).Numerical simulation of two-dimensional unsteady Giesekus flow over a circular cylinder.JOURNAL OF NON-NEWTONIAN FLUID MECHANICS,294.

Peng, Sai,et al."Numerical simulation of two-dimensional unsteady Giesekus flow over a circular cylinder".JOURNAL OF NON-NEWTONIAN FLUID MECHANICS 294(2021).