Heat transfer in an annular space fitted with heating isothermal blocks: Numerical bifurcation for low blocks height

Idrissi, Ahmed; Cheddadi, Abdesselam; Ouazzani, M. T.

doi:10.1016/j.csite.2015.11.002

Cited by 7 publications

(4 citation statements)

References 17 publications

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“…Considering both the accuracy and the computational time issue, the following calculations were all performed with the selected grid size 65×65. The validation of the calculation code was carried out by comparing the results of the heat transfer rate in the case with a very low block height (h = 0.015) with those for the cavity without blocks (h = 0) obtained by Cheddadi et al, [34] as well as with those found by Idrissi et al, [27] in the case of h = 0.015. The results are in good agreement as seen in Table 1.…”

Section: Computational Methodologymentioning

confidence: 99%

“…A critical Rayleigh number has been determined, characterizing the appearance of multicellular regime, where the overall heat transfer rate is greater than that of the unicellular one obtained without blocks. The influence of initial conditions on the flow structure and the overall heat transfer rate has been investigated by the same authors Idrissi et al, [27]. The study shows the existence of a bifurcation point separating two flows regimes: uni-and bi-cellular.…”

Section: Introductionmentioning

confidence: 99%

“…The results of studies show that the multicellular regime has in general the effect of increasing the heat transfer rate [12][13][24][25][26][27]. However, the results obtained by [20][21][22][23] dealing with natural convection in a square cavity show that the formation of the multicellular flow is not necessarily equivalent to an increase in heat transfer.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Flow Regimes on The Heat Transfer in an Annular Cavity with Two Internal Blocks

Amraoui¹,

Cheddadi²,

Ouazzani³

2020

ARFMTS

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The present paper analyses numerically the flow fields in an annular cylindrical cavity provided with two isothermal blocks of different heights for Rayleigh numbers ranging from 10 3 to 10 4. The steady-state solutions have been obtained using the discretization of the governing equations with the Centered Finite Difference method based on the Alternating Direction Implicit (ADI) scheme. The two blocks are arranged in the upper part of the annular cavity at φm = 0.82π. The radii ratio and the thickness of the blocks are kept fixed at the respective values of R = 2 and w = 0.203. For low block heights between 0.015 and 0.078, only the unicellular flow regime (UCR) is observed regardless of the Rayleigh number. The heights ranging from 0.093 to 0.953 give rise to flows that are more complex. The results are illustrated in the form of streamlines, isotherms, average Nusselt number and the size of the secondary cell located in the upper part of the cavity. For given Rayleigh numbers, the critical heights hc,app, which characterize the appearance of the bicellular flow regime (BCR) and those describing the development of this regime, hc,inc, are determined. Similarly, for given heights, the critical Rayleigh numbers, Rac,app and Rac,inc, which respectively determine the appearance of the BCR regime and the increase of the size and intensity of the secondary cell, are specified. The influence of these parameters on the heat transfer is studied.

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Section: Computational Methodologymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Effect of Flow Regimes on The Heat Transfer in an Annular Cavity with Two Internal Blocks

Amraoui¹,

Cheddadi²,

Ouazzani³

2020

ARFMTS

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“…Various optimal configurations have been proposed based on practical and industrial requirements. The study of the effect of changing initial conditions carried out by Idrissi et al [21], showed the existence of a bifurcation point separating two flow regimes: uni-and bi-cellular. The bicellular regime leads to substantial enhancement of the heat transfer rate compared to the unicellular one.…”

Section: Introductionmentioning

confidence: 99%

Effect of Fin Height and Rayleigh Number with Small Increments on Convective Heat Transfer in a Horizontal Annulus

Amraoui¹,

Cheddadi²,

Ouazzani³

2020

IJHT

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The purpose of this paper is to investigate numerically the laminar natural convection in an annular space bounded by two coaxial horizontal cylinders equipped with two fins of height h, ranging from 0.015 to 0.953. Rayleigh number, Ra, is considered between 10 3 and 10 4 . The effect of the fin height and Rayleigh number, both varied with small increments is analyzed. The resulting flow structures and heat transfer rates as well as the effectiveness of the system are presented. The results show that for each Ra the increase in h leads to a decrease or an increase in heat transfer rate depending on the fins height value, and that the case without fins can be more favorable to the heat transfer rate compared to the case with fins for intervals of h obtained as a function of Ra. It is also shown that the increase in the Rayleigh number does not necessarily correspond to an increase in heat transfer rate. In particular, the disappearance of the bicellular regime leads to a decrease of the heat transfer rate when Ra increases.

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Numerical Study of Laminar Natural Convection in a Finned Annulus: Low Isothermal Blocks Positions

Touzani

Idrissi

Cheddadi

et al. 2019

J Eng Phys Thermophy

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Heat transfer in an annular space fitted with heating isothermal blocks: Numerical bifurcation for low blocks height

Cited by 7 publications

References 17 publications

Effect of Flow Regimes on The Heat Transfer in an Annular Cavity with Two Internal Blocks

Effect of Flow Regimes on The Heat Transfer in an Annular Cavity with Two Internal Blocks

Effect of Fin Height and Rayleigh Number with Small Increments on Convective Heat Transfer in a Horizontal Annulus

Numerical Study of Laminar Natural Convection in a Finned Annulus: Low Isothermal Blocks Positions

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