Numerical study of particle dispersion behind a sudden expansion geometry and its effect on step heights

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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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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Effect of Air Exchange Rate on Particle Decay in a Cleanroom: A Numerical Study

E3S Web of Conferences ◽

10.1051/e3sconf/201911101037 ◽

2019 ◽

Vol 111 ◽

pp. 01037

Author(s):

Yunus Emre Cetin ◽

Mete Avci ◽

Orhan Aydin

Keyword(s):

Exchange Rate ◽

Turbulence Model ◽

Recovery Time ◽

Numerical Study ◽

Particle Dispersion ◽

Discrete Phase Model ◽

Governing Equations ◽

Air Exchange Rate ◽

Particle Decay ◽

Discrete Phase

In this study, particle decay in a cleanroom is investigated numerically. A commercial CFD package, FLUENT, is used in the analysis. The governing equations are solved by using the k-å turbulence model. For particle dispersion, the discrete phase model (DPM) is applied. Four different air change rates (3-10-25-43 ACH) with three particle diameters (0,5-5-10 ìm) are considered. It is shown that 10 ACH satisfies the needs in terms of recovery time.

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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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Numerical Study on Two-Dimensional Symmetric Sudden Expansion Channel Flow

The Proceedings of Conference of Chugoku-Shikoku Branch ◽

10.1299/jsmecs.2002.40.227 ◽

2002 ◽

Vol 2002.40 (0) ◽

pp. 227-228

Author(s):

Suketugu NAKANISHI ◽

Tomohiro KIJIMA ◽

Motoyasu SAKURAI ◽

Hideo OSAKA

Keyword(s):

Channel Flow ◽

Numerical Study ◽

Sudden Expansion ◽

Two Dimensional

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610 Numerical Study for Flow Control in Sudden Expansion Channel

The Proceedings of Conference of Chugoku-Shikoku Branch ◽

10.1299/jsmecs.2009.47.201 ◽

2009 ◽

Vol 2009.47 (0) ◽

pp. 201-202

Author(s):

Toshiya Uesugi ◽

Chiharu FUKUSHIMA ◽

Koji UTSUNOMIYA ◽

Suketsugu NAKANISHI

Keyword(s):

Flow Control ◽

Numerical Study ◽

Sudden Expansion

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Mixed Convection in a Horizontal Porous Duct With a Sudden Expansion and Local Heating From Below

Journal of Heat Transfer ◽

10.1115/1.2826029 ◽

1999 ◽

Vol 121 (3) ◽

pp. 653-661 ◽

Cited By ~ 8

Author(s):

Y. Yokoyama ◽

F. A. Kulacki ◽

R. L. Mahajan

Keyword(s):

Heat Transfer ◽

Convective Heat ◽

Numerical Study ◽

Local Heating ◽

Lower Surface ◽

Porous Matrix ◽

Sudden Expansion ◽

Nusselt Numbers ◽

Matrix Heat ◽

Heating From Below

Results are reported for an experimental and numerical study of forced and mixed convective heat transfer in a liquid-saturated horizontal porous duct. The cross section of the duct has a sudden expansion with a heated region on the lower surface downstream and adjacent to the expansion. Within the framework of Darcy’s formulation, the calculated and measured Nusselt numbers for 0.1 < Pe < 100 and 50 < Ra < 500 are in excellent agreement. Further, the calculated Nusselt numbers are very close to those for the bottom-heated flat duct. This finding has important implications for convective heat and mass transfer in geophysical systems and porous matrix heat exchangers. The calculations were also carried out for glass bead-packed beds saturated with water using non-Darcy’s formula. The streamlines in the forced convection indicate that, even with non-Darcy effects included, recirculation is not observed downstream of an expansion and the heat transfer rate is decreased but only marginally.

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