Numerical study of three recirculation zones in the unilateral sudden expansion flow

Using the standard k-e turbulence model, an incompressible, axisymmetric turbulent flow with a sudden expansion was simulated. Effect of Prandtl number on heat transfer characteristics downstream of the expansion was investigated. The simulation revealed circulation downstream of the expansion. A secondary circulation (corner eddy) was also predicted. Reattachment was predicted at approximately 10 step heights. Corresponding to Prandtl number of 7.0, a peak Nusselt number 13 times the fully-developed value was predicted. The ratio of peak to fully-developed Nusselt number was shown to decrease with decreasing Prandtl number. Location of maximum Nusselt number was insensitive to Prandtl number.

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Numerical study of laminar flow in a sudden expansion obstacled channel

Thermal Science ◽

10.2298/tsci121029105m ◽

2015 ◽

Vol 19 (2) ◽

pp. 657-668 ◽

Cited By ~ 1

Author(s):

Khudheyer Mushatet ◽

Qais Rishakb ◽

Mohsen Fagr

Keyword(s):

Laminar Flow ◽

Numerical Study ◽

Sudden Expansion

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The Effect of Red Cell Dynamics on Platelet Spatial Distribution in Sudden Expansion

ASME 2007 Summer Bioengineering Conference ◽

10.1115/sbc2007-176027 ◽

2007 ◽

Author(s):

Rui Zhao ◽

Joie Marhefka ◽

Marina Kameneva ◽

James Antaki

Keyword(s):

Spatial Distribution ◽

Sudden Expansion ◽

Red Cell ◽

Common Complication ◽

Complex Flow ◽

Cell Dynamics ◽

Stagnation Points ◽

Recirculation Zones

Thrombosis is a common complication associated with blood contacting devices [1]. Platelets often (or preferably) deposit in specific regions which contain complex flow featuring separations, recirculation zones and stagnation points [2, 3].

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Numerical Study of the Velocity Decay of Offset Jet in a Narrow and Deep Pool

Water ◽

10.3390/w11010059 ◽

2018 ◽

Vol 11 (1) ◽

pp. 59 ◽

Cited By ~ 1

Author(s):

Xin Li ◽

Maolin Zhou ◽

Jianmin Zhang ◽

Weilin Xu

Keyword(s):

Flow Field ◽

Numerical Study ◽

Expansion Ratio ◽

Sudden Expansion ◽

Mean Velocity ◽

Cross Sectional ◽

Potential Core ◽

Early Region ◽

Flow Development ◽

Offset Jet

The present study examines the configuration of an offset jet issuing into a narrow and deep pool. The standard k-ε model with volume-of-fluid (VOF) method was used to simulate the offset jet for three exit offset ratios (OR = 1, 2 and 3), three expansion ratios (ER = 3, 4 and 4.8), and different jet exits (circular and rectangular). The results clearly show significant effects of the circumference of jet exits (Lexit) in the early region of flow development, and a fitted formula is presented to estimate the length of the potential core zone (LPC). Analysis of the flow field for OR = 1 showed that the decay of cross-sectional streamwise maximum mean velocity (Um) in the transition zone could be fitted by power law with the decay rate n decreased from 1.768 to 1.197 as the ER increased, while the decay of Um for OR = 2 or 3 was observed accurately estimated by linear fit. Analysis of the flow field of circular offset jet showed that Um for OR = 2 decayed fastest due to the fact that the main flow could be spread evenly in floor-normal direction. For circular jets, the offset ratio and expansion ratio do not affect the spread of streamwise velocity in the early region of flow development. It was also observed that the absence of sudden expansion of offset jet is analogous to that of a plane offset jet, and the flow pattern is different.

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A Numerical Study of Sand Particle Erosion in a Series of Ball Seats in Gas-Particle Two-Phase Flow

Volume 5: Multiphase Flow ◽

10.1115/ajkfluids2019-5497 ◽

2019 ◽

Author(s):

A. Rasteh ◽

A. Farokhipour ◽

M. A. Rasoulian ◽

Z. Mansoori ◽

M. Saffar-Avval ◽

...

Keyword(s):

Oil And Gas ◽

Numerical Study ◽

Cone Angle ◽

Gas Production ◽

Sudden Expansion ◽

Sand Particle ◽

Two Phase ◽

Operational Conditions ◽

Wide Range ◽

Single Cone

Abstract Fracking (fracturing) is of great importance for enhancing oil and gas production from low permeability reservoirs. Since in fracking fluid, suspension of sand particles are used, the erosion failure of fracturing equipment has become an increasing concern. Accordingly, investigation of erosion of commonly used fittings such as ball seats in order to decrease its adverse consequences has attracted considerable attentions. Although the erosion wear of gas-solid flows in the pipe sudden expansion was investigated in the literature, the effect of particle size, ball seat shape and the contraction configurations on the erosion-induced wear is not fully understood. This study is aimed to explore the most erosion-resistant configuration of a ball seat under various operational conditions. A CFD model is used and a wide range of geometries are investigated. The studied configurations are categorized in three main groups including single cone, double cone and curved cone. In each category, different cone angles and curve styles are considered. The results showed that, among the single cone ball seats, the cone angle of 15° is the most erosion-resistant configuration. It was also shown that the third-order curve style cone has the best erosion performance.

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