CFD Simulation of Heat Transfer and Turbulent Fluid Flow over a Double Forward-Facing Step

Togun, Hussein; Shkarah, Ahmed Jassim; Kazi, S.N.; Badarudin, A.

doi:10.1155/2013/895374

Cited by 27 publications

(5 citation statements)

References 29 publications

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“…They observed results similar to those in the previous experimental studies regarding separation and reattachment length at the top and bottom wall of the tube. Separation and reattachment regions of different fluid-flow over the backward and forward-facing arrangements were investigated by numerous researchers [6][7][8][9][10][11][12], and they achieved similar results.…”

Section: Introductionmentioning

confidence: 97%

Effect of flow separation of TiO2 nanofluid on heat transfer in the annular space of two concentric cylinders

et al. 2020

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In the wake of energy crises, the researchers are encouraged to explore new ways of enhancement in the thermal performance of heat exchanging equipment. In the current research, the SST k-ω model and finite volume method were employed to augment heat transfer into the separation flow of TiO 2 nanofluid in the annular space of two concentric cylinders. In the present investigation TiO 2 nanoparticles of volume fractions, 0.5%-2% at Reynolds number range of 10000-40000, and contraction ratios from 1 to 2 were considered at constant heat flux boundary condition. Simulation results reveal that the highest enhancement in the heat transfer coefficient is corresponding to the annular pipe with a contraction ratio of 2 due to the generated re-circulation flow zone that begins after the separation point on the wall. Further, the surface heat transfer coefficient enhances with the increase of nanoparticles volume fraction and Reynolds number. The velocity distribution profile before and after the steps reveals that increasing the height of the step and Reynolds number, re-circulation regions also increases. Numerical results indicate that the highest pressure drop occurs at the Re = 40000 and contraction ratio of 2.

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Section: Introductionmentioning

confidence: 97%

Effect of flow separation of TiO2 nanofluid on heat transfer in the annular space of two concentric cylinders

et al. 2020

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“…Nanofluids with fabricated geometries are increasingly employed to improve heat transfer in various applications [ 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 ]. Dadheech et al [ 6 ] studied natural convection in the attendance of an angled magnetic field and compared the thermal behavior of MoS 2 /C2H 6 O 2 and SiO 2 -MoS 2 /C 2 H 6 O 2 nanofluids.…”

Section: Introductionmentioning

confidence: 99%

Efficient Heat Transfer Augmentation in Channels with Semicircle Ribs and Hybrid Al2O3-Cu/Water Nanofluids

Togun

Homod

Yaseen‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬

et al. 2022

Nanomaterials

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Global technological advancements drive daily energy consumption, generating additional carbon-induced climate challenges. Modifying process parameters, optimizing design, and employing high-performance working fluids are among the techniques offered by researchers for improving the thermal efficiency of heating and cooling systems. This study investigates the heat transfer enhancement of hybrid “Al2O3-Cu/water” nanofluids flowing in a two-dimensional channel with semicircle ribs. The novelty of this research is in employing semicircle ribs combined with hybrid nanofluids in turbulent flow regimes. A computer modeling approach using a finite volume approach with k-ω shear stress transport turbulence model was used in these simulations. Six cases with varying rib step heights and pitch gaps, with Re numbers ranging from 10,000 to 25,000, were explored for various volume concentrations of hybrid nanofluids Al2O3-Cu/water (0.33%, 0.75%, 1%, and 2%). The simulation results showed that the presence of ribs enhanced the heat transfer in the passage. The Nusselt number increased when the solid volume fraction of “Al2O3-Cu/water” hybrid nanofluids and the Re number increased. The Nu number reached its maximum value at a 2 percent solid volume fraction for a Reynolds number of 25,000. The local pressure coefficient also improved as the Re number and volume concentration of “Al2O3-Cu/water” hybrid nanofluids increased. The creation of recirculation zones after and before each rib was observed in the velocity and temperature contours. A higher number of ribs was also shown to result in a larger number of recirculation zones, increasing the thermal performance.

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“…Also Alibek and Zhandaulet [2] presented numerical investigation on influence geometry for fluid flow and heat transfer over Forward-Backward facing step by employing (DNS). Turbulent water flow and heat transfer over horizontal DFFS step is numerically studied by Togun et al [3]. Increasing of Reynolds number and step height was noticed lead to rise in Nusselt number.…”

Section: Introductionmentioning

confidence: 99%

“…Generally, effects of modification the channels on thermal performance such as reducing or expanding passage, fins, ribbed channel are investigated in various numerical and experimental studies [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23].…”

Section: Introductionmentioning

confidence: 99%

Hybrid Al2O3-Cu/water nanofluid flow and heat transfer over vertical double forward-facing step

2021

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Turbulent heat transfer and hybrid Al2O3-Cu/nanofluid over vertical double forward facing-stepis numerically conducted. K-? standard model based on finite volume method in two dimensional are applied to investigate the influences of Reynolds number, step height, volume fractions hybrid Al2O3-Cu/nanofluid on thermal performance. In this paper, different step heights for three cases of vertical double FFS are adopted by five different of volume fractions of hybrid (Al2O3-Cu/water) nanofluid varied for 0.1, 0.33, 0.75, 1, and 2, while the Reynolds number different between 10000 to 40000 with temperature is constant. The main findings revealed that rise in local heat transfer coefficients with raised Reynolds number and maximum heat transfer coefficient was noticed at Re=40000. Also rises in heat transfer coefficient detected with increased volume concentrations of hybrid (Al2O3-Cu/water) nanofluid and the maximum heat transfer coefficient found at hybrid Al2O3-Cu/water nanofluid of 2% in compared with others. It?s also found that rise in surface heat transfer coefficient at 1ststep-case 2 was greater than at 1ststep-case 1 and 3 while was higher at 2ndstep-case 3. Average heat transfer coefficient with Reynolds number for all cases are presented in this paper and found that the maximum average heat transfer coefficient was at case 2 compared with case 1 and 3. Gradually increases in skin friction coefficient remarked at 1stand 2ndsteps of the channel and drop in skin friction coefficient was obtained with increased of Reynolds number. Counter of velocity was presented to show the recirculation regions at first and second steps as clarified the enrichment in heat transfer rate. Furthermore, the counter of turbulence kinetic energy contour was displayed to provide demonstration for achieving thermal performance at second step for all cases.

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CFD Simulation of Heat Transfer and Turbulent Fluid Flow over a Double Forward-Facing Step

Cited by 27 publications

References 29 publications

Effect of flow separation of TiO2 nanofluid on heat transfer in the annular space of two concentric cylinders

Effect of flow separation of TiO2 nanofluid on heat transfer in the annular space of two concentric cylinders

Efficient Heat Transfer Augmentation in Channels with Semicircle Ribs and Hybrid Al2O3-Cu/Water Nanofluids

Hybrid Al2O3-Cu/water nanofluid flow and heat transfer over vertical double forward-facing step

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