Bifurcation phenomenon of inertial viscoelastic flow through gradual expansions

Norouzi, M.; Shahmardan, Mohammad Mohsen; Shahbani-Zahiri, A.

doi:10.1007/s00397-015-0841-3

Cited by 13 publications

(5 citation statements)

References 32 publications

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“…Also, the parameter shows the ratio of Newtonian viscosity to the total viscosity ( = s ∕ 0 ) that the total viscosity ( 0 ) is achieved from the summation of s and p . Whenever the value of is equal to 0.5 or more, the elastic property acts as a stabilizing factor in the flow pattern and the length of vortices are decreased; while for ≪ 0.5 , the We (Weissenberg number) enhancement creates an instability in the flow pattern and the recirculation regions are developed [6].…”

Section: Governing Equationsmentioning

confidence: 99%

“…In the recent decades, many researchers investigated the isothermal non-Newtonian fluid flow through the planar channel with sudden and gradual expansion [2][3][4][5][6][7][8][9][10][11]. Also, there are many types of research for non-isothermal non-Newtonian fluid flow inside the straight pipe and channel, while very few studies have been done for viscoelastic flow through a planar channel with sudden expansion.…”

Section: Introductionmentioning

confidence: 99%

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Effects of fluid inertia and elasticity and expansion angles on recirculation and thermal regions of viscoelastic flow in the symmetric planar gradual expansions

Shahbani-Zahiri

Shahmardan

Norouzi

2018

J Braz. Soc. Mech. Sci. Eng.

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The formation and growth of symmetric and asymmetric recirculation regions play an important role in the viscous dissipations, temperature distribution, and heat transfer rate. In this study, the inertial and non-isothermal flow of viscoelastic fluid has been simulated in the planar channel with a 1:3 symmetric gradual expansion for different Reynolds and elasticity numbers at three expansion angles of 30°, 45°, and 60°. Also, the thermal boundary condition of constant temperature has been used on the walls, and the constitutive equation of exponential Phan Thien-Tanner has been employed for modeling the polymeric stresses of the viscoelastic fluid. Due to the significant effect of temperature on the properties of the viscoelastic fluid, and the role of viscous dissipation in heat generation, the fluid properties are considered temperature dependent, and the terms of viscous dissipation are considered in the energy equation. The main purpose of current study is to investigate the effects of fluid inertia and elasticity and the expansion angles on the flow pattern, heat transfer characteristics, and viscous dissipation of inertial viscoelastic flow in the planar channel with gradual expansions. Therefore, the streamlines, length of vortices, isothermal lines, total viscous dissipations, and local and mean Nusselt numbers (Nu) have been examined inside the channel expansion for different Reynolds and elasticity numbers in the range of 10 ≤ Re ≤ 100 and 0.01 ≤ El ≤ 2. The results show that the maximum values of local Nusselt numbers are enhanced by increasing the Reynolds and elasticity numbers and the expansion angle for the hydrodynamically and thermally developing conditions.

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Section: Governing Equationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effects of fluid inertia and elasticity and expansion angles on recirculation and thermal regions of viscoelastic flow in the symmetric planar gradual expansions

Shahbani-Zahiri

Shahmardan

Norouzi

2018

J Braz. Soc. Mech. Sci. Eng.

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“…3(b) (Fig. 3(c) Most authors cited in this paper explained the asymmetric flow phenomenon by the Coanda effect (Fearn et al, 1990;Oliveira 2003;Ternik et al 2006;Dhinakaran et al 2013 andNorouzi et al 2015), where any perturbation of the flow field, pushing the main flow to one of the sides of the expansion, gives rise to larger velocities and lower pressures there, and hence the asymmetry (i.e. two vortices of unequal size) will naturally tend to be accentuated Oliveira (2003).…”

Section: Validationmentioning

confidence: 94%

“…Illustration of (a) two-dimensional 1:3 gradual planar expansion geometry considered in the study and (b) blocks that were used; (c) mesh distribution near the expansion plane(Norouzi et al (2015) studied numerically the flow of viscoelastic fluid through a 1: 3 planar gradual expansion. Three angles of 30, 45, and 60° are selected to clarify the effect of expansion angles.…”

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confidence: 99%

Steady Flow of Purely Viscous Shear-Thinning Fluids in a 1:3 Planar Gradual Expansion

Menouer

Chemloul

Chaib

et al. 2019

JAFM

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Laminar flow of non-Newtonian fluid (shear-thinning) through a 1:3 planar gradual expansion is numerically investigated, for various Power-Law index (0.6, 0.8 and 1.0) and expansion angles (15, 30, 45, 60 and 90°) at different generalized Reynolds number (1 ≤ Reg ≤ 400). The study of these parameters effect on the flow pattern allowed the determination of the two critical generalized Reynolds numbers (Regcr1 and Regcr2), which correspond to the transition from the symmetric to the asymmetric flow and the appearance of the third recirculation zone respectively. The results showed that decreasing the Power-Law index or the expansion angle stabilizes the flow by increasing significantly the two critical generalized Reynolds numbers. In order to predict the two critical generalized Reynolds numbers, two correlations have been proposed.

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“…Furthermore, total viscosity of viscoelastic fluid ( 0 η ) is achieved by the summation of solvent and polymeric additives viscosities at zero shear rate ( 0 S P η η η = = ). The elasticity parameter serves as a stabilizing factor for viscoelastic fluid flow with the ratio of solvent viscosity ( β ) equal to 0.5 or higher, while for higher polymeric concentration ( 1 β << ), the elasticity parameter operates as an unstable factor in the event of bifurcation phenomena [16]. Therefore, the ratio of the solvent viscosity to the total viscosity is chosen to be very low ( In this study, the fluid properties such as fluid viscosity, relaxation time, specific heat capacity and thermal conductivity are varied with temperature and the dependence of these parameters on the temperature are represented as follows [17]:…”

Section: Equationsmentioning

confidence: 99%

Effects of Elasticity Number on the Heated Flow of Viscoelastic Fluid inside Planar Channel with a Symmetric Abrupt Expansion

Zahiri¹,

Shahmardan²,

Norouzi³

2017

ujas

Self Cite

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In this work, we have numerically studied the heat transfer of viscoelastic fluid flow inside a planar channel with 1:3 abrupt expansion. For modeling rheological behavior of non-creeping flow related to the viscoelastic fluid which includes both the effects of shear-thinning and elasticity, the constitutive equation of exponential Phan Thien-Tanner (EPTT) is used. Also, thermal boundary condition of constant temperature at the walls and inlet of channel with internal heat generated by the viscous dissipation are considered. Because of high temperature differences in the current study, the fluid properties such as fluid viscosity, relaxation time, specific heat capacity and thermal conductivity have a function of temperature. For coupling the variables of velocity, pressure and temperature, the PISO algorithm is employed and finite volume method (FVM) imposed on the collocated grid to discretize the governing equations. The main propose of the present study is to examine the effects of elastic property on the size of recirculation regions, temperature distribution, local and mean Nusselt numbers.

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Bifurcation phenomenon of inertial viscoelastic flow through gradual expansions

Cited by 13 publications

References 32 publications

Effects of fluid inertia and elasticity and expansion angles on recirculation and thermal regions of viscoelastic flow in the symmetric planar gradual expansions

Effects of fluid inertia and elasticity and expansion angles on recirculation and thermal regions of viscoelastic flow in the symmetric planar gradual expansions

Steady Flow of Purely Viscous Shear-Thinning Fluids in a 1:3 Planar Gradual Expansion

Effects of Elasticity Number on the Heated Flow of Viscoelastic Fluid inside Planar Channel with a Symmetric Abrupt Expansion

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