Archival correlations for average heat transfer coefficients for non-circular and circular cylinders and for spheres in cross-flow

Sparrow, E. M.; Abraham, John; Tong, Jimmy C.K.

doi:10.1016/j.ijheatmasstransfer.2004.06.024

Cited by 160 publications

(74 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…It is observed that out of the data shown in table, 71% of researchers have reported the value of mean Nusselt number close to our value of 3.29, whereas others have reported a higher value close to 3.48. The only value which departs from the rest is that reported in [68].…”

Section: Code Validationcontrasting

confidence: 58%

Prediction of Better Flow Control Parameters in MHD Flows Using a High Accuracy Finite Difference Scheme

Rejeesh¹,

Udhayakumar²,

Sekhar³

et al. 2017

AJCM

View full text Add to dashboard Cite

We have successfully attempted to solve the equations of full-MHD model within the framework of ψ ω − formulation with an objective to evaluate the performance of a new higher order scheme to predict better values of control parameters of the flow. In particular for MHD flows, magnetic field and electrical conductivity are the control parameters. In this work, the results from our efficient high order accurate scheme are compared with the results of second order method and significant discrepancies are noted in separation length, drag coefficient and mean Nusselt number. The governing Navier-Stokes equation is fully nonlinear due to its coupling with Maxwell's equations. The momentum equation has several highly nonlinear body-force terms due to full-MHD model in cylindrical polar system. Our high accuracy results predict that a relatively lower magnetic field is sufficient to achieve full suppression of boundary layer and this is a favorable result for practical applications. The present computational scheme predicts that a drag-coefficient minimum can be achieved when , it is found that the heat transfer rate is independent of electrical conductivity of the fluid. From the numerical values of physical quantities, we establish that the order of accuracy of the computed numerical results is fourth order accurate by using the method of divided differences.

show abstract

Section: Code Validationcontrasting

confidence: 58%

Prediction of Better Flow Control Parameters in MHD Flows Using a High Accuracy Finite Difference Scheme

Rejeesh¹,

Udhayakumar²,

Sekhar³

et al. 2017

AJCM

View full text Add to dashboard Cite

show abstract

“…Almost no earlier studies have been concerned with this particular cylinder configuration. The only two exceptions we are aware of are the compilation of heat transfer data by Sparrow et al [13] in which 80-years old measurements of the Nusselt number by Hilpert [22] are re-analysed, and the recent CFD-computations by Tian and Wu [15] which were limited to corner orientation and to Reynolds numbers below 80. The influence of the orientation of a hexagonal cylinder relative to the incoming flow on the near-wake flow has never been studied before.…”

Section: Discussion and Concluding Remarksmentioning

confidence: 99%

“…[11] were based on the side d rather than on the projected height h. Very recently, Yoon et al [12] The only empirically-based paper on hexagonal cylinders (i.e. N = 6) is that by Sparrow et al [13]. They addressed the heat transfer from some different non-circular cylinders in cross-flow and focused on the crucial role played by choice of the characteristic length in the Nusselt-Reynolds number correlation.…”

Section: E-mail Address: Hatefkhaledi@ntnuno (Ha Khaledi)mentioning

confidence: 99%

On vortex shedding from a hexagonal cylinder

Khaledi

Andersson

2011

Physics Letters A

View full text Add to dashboard Cite

The unsteady wake behind a hexagonal cylinder in cross-flow is investigated numerically. The timedependent three-dimensional Navier-Stokes equations are solved for three different Reynolds numbers Re and for two different cylinder orientations. The topology of the vortex shedding depends on the orientation and the Strouhal frequency is generally higher in the wake of a face-oriented cylinder than behind a corner-oriented cylinder. For both orientations a higher Strouhal number St is observed when Re is increased from 100 to 500 whereas St is unaffected by a further increase up to Re = 1000. The distinct variation of St with the orientation of the hexagonal cylinder relative to the oncoming flow is opposite of earlier findings for square cylinder wakes which exhibited a higher St with corner orientation than with face orientation.

show abstract

“…Unfortunately, no Nusselt number correlation was found in the literature for a flat plate in cross flow that is valid for this range of Reynolds numbers. Because this analysis is purely meant to be qualitative, our discussion will make use of the relation derived by Hilpert [23,24] (with the correct values of the constants from [25])…”

Section: = Rementioning

confidence: 99%

Convection Ignition of Live Forest Fuels

McAllister¹,

Finney²

2014

Fire Saf. Sci.

View full text Add to dashboard Cite

Wildland fires are an extremely costly and deadly problem. Crown fires, where live foliage ignites and burns, are particularly unpredictable -in part because live fuel ignition and combustion is poorly understood. Many wildland fire models assume radiation is the controlling heat transfer mechanism. However, there is a growing indication that radiation is insufficient to ignite the small, thin fuel particles that carry a wildland fire and that convective heating and flame bathing is a critical component. Unfortunately, ignition by convection heating of any fuel is poorly understood. Ignition of live forest fuels by any means is also completely unknown due to complicated moisture content and fuel chemistry considerations. To gain some insight into the wildland fire problem, an apparatus was built using two 6.5 kW electrical heaters to heat gas (air, nitrogen, etc.) over a range of temperatures from ambient up to 1200°C. The flow rate of these "airtorches" is adjustable. This apparatus was used to convectively ignite a range of both live and dead forest fuels. Fuels from all over the United States where used including Southern California, Utah, Florida, and Montana. To examine ignition threshold conditions and to have distinguishable differences in ignition times, air temperatures of 500°C and 600°C were used. The airflow rate varied slightly from 1.3 m/s to 1.4 m/s due to the density difference. Because live forest fuels contain large amounts of water, the evolution of both water and carbon dioxide was measured with time using a differential gas analyzer. Flaming ignition was seen for all dead fuels at 500°C, but the live fuels mostly showed glowing ignition. At 600°C, all fuels showed flaming ignition within 1-26 sec. Interestingly, all live fuels were still actively releasing water at ignition, implying there are steep temperature gradients within these physically thin fuels (i.e. not thermally thin). Simple heat transfer analysis in conjunction with the water evolution information was used to help explain the differences in ignition times due to fuel geometry.

show abstract

Archival correlations for average heat transfer coefficients for non-circular and circular cylinders and for spheres in cross-flow

Cited by 160 publications

References 14 publications

Prediction of Better Flow Control Parameters in MHD Flows Using a High Accuracy Finite Difference Scheme

Prediction of Better Flow Control Parameters in MHD Flows Using a High Accuracy Finite Difference Scheme

On vortex shedding from a hexagonal cylinder

Convection Ignition of Live Forest Fuels

Contact Info

Product

Resources

About