@article{Toprak202377,
title = {LONGITUDINAL THERMAL CONDUCTIVITY OF Cu-SWCNT CORE-SHELL NANOWIRE: MOLECULAR DYNAMICS SIMULATIONS},
author = {Kasim Toprak and Yildiz Bayazitoglu},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85159154476&doi=10.1615%2fHeatTransRes.2022044425&partnerID=40&md5=f5dc57c56947ec56a143fb7cf8346175},
doi = {10.1615/HeatTransRes.2022044425},
year = {2023},
date = {2023-01-01},
journal = {Heat Transfer Research},
volume = {54},
number = {4},
pages = {77 – 89},
abstract = {The phonon thermal conductivity of copper core and armchair single-walled carbon nanotube shell (Cu-SWCNT) coaxial nanostructure is presented using the non-equilibrium molecular dynamics (NEMD) simulations method. The study aims to investigate how the ultrathin Cu nanowire affects the thermal conductivity of Cu-SWCNT. The results have revealed that the thermal conductivity of Cu-SWCNT is more than two orders of magnitude higher than that of the Cu core with the contribution of the SWCNT shell. The influences of length, chirality, defect, and core filling on the thermal conductivity of Cu-SWCNT are studied using the two most used C-C potentials, the AIREBO and Tersoff potentials. The bare SWCNT and Cu-SWCNT simulation results revealed that the thermal conductivity using the AIREBO potential is lower than that of Tersoff. Although the thermal conductivity increases with the length of the coaxial tube, it decreases with the chirality and the filling ratio. Increasing the chirality of SWCNT and the Cu core-filling ratio can boost the core copper's contributions to the thermal conductivity, reducing the overall thermal conductivity. The lengths of the thermostat and buffer regions do not significantly affect the thermal conductivity. In addition, the vacancy concentration in heat flow regions effectively reduces thermal conductivity, whereas the vacancy in the thermostat regions does not have a significant effect. The thermal rectification factor defined as changing the imposed heat flux direction is up to 1.73%for the Cu-SWCNT and 2.63% for the SWCNT. © 2023 by Begell House, Inc.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Ulu202219365,
title = {Spray Analysis of Biodiesels Derived from Various Biomass Resources in a Constant Volume Spray Chamber},
author = {A Ulu and G Yildiz and A D Rodriguez and Ü Özkol},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85132107803&doi=10.1021%2facsomega.2c00952&partnerID=40&md5=995ab045ec0310695a47b69c61b69c80},
doi = {10.1021/acsomega.2c00952},
year = {2022},
date = {2022-01-01},
journal = {ACS Omega},
volume = {7},
number = {23},
pages = {19365-19379},
abstract = {This research aimed to analyze the spray characteristics of various biodiesels, which have rarely been investigated in terms of spray analysis in the literature compared to fossil diesel. For this purpose, four different methyl ester-type biodiesels were produced from canola, corn, cottonseed, and sunflower oils. These feedstocks were selected due to their wide availability in Turkey and being among the significant resources for biodiesel production. Measured physical properties of biodiesel samples showed that biodiesel fuels had, on average, 1.7 to 1.9 times higher viscosities, 5.3 to 6.6% larger densities, and 37 to 39.1% higher contact angle values than the reference diesel fuel. Spray characteristics of all fuels were experimentally examined in a constant volume spray chamber under chamber pressures of 0, 5, 10, and 15 bar and injection pressures of 600, 800, and 1000 bar. All tested biodiesels performed, on average, 3 to 20% longer spray penetration lengths, 5 to 30% narrower spray cone angles, and 5-18% lesser spray areas than the reference diesel fuel under chamber pressures of 5 and 10 bar. No significant differences occurred at 15 bar ambient pressure between biodiesels and diesel. In addition, analytical and empirical predictions showed that biodiesels had around 21.2-35.1% larger SMD values and approximately 7% lower air entrainment. © 2022 American Chemical Society. All rights reserved.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Ulu2022b,
title = {Experimental investigation of spray characteristics of ethyl esters in a constant volume chamber},
author = {A Ulu and G Yildiz and Ü Özkol and A D Rodriguez},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85125134221&doi=10.1007%2fs13399-022-02476-3&partnerID=40&md5=f56d167f075688de07dc30653fa40c64},
doi = {10.1007/s13399-022-02476-3},
year = {2022},
date = {2022-01-01},
journal = {Biomass Conversion and Biorefinery},
abstract = {Abstract: Biodiesels are mainly produced via the utilization of methanol in transesterification, which is the widespread biodiesel production process. The majority of this methanol is currently obtained from fossil resources, i.e. coal and natural gas. However, in contrast with methanol, biomass-based ethanol can also be used to produce biodiesels; this could allow the production line to become fully renewable. This study aimed to investigate the spray characteristics of various ethyl ester type biodiesels derived from sunflower and corn oils in comparison to methyl esters based on the same feedstocks and reference petroleum-based diesel. Spray penetration length (SPL) and spray cone angle (SCA) were experimentally evaluated in a constant volume chamber allowing optical access, under chamber pressures of 0, 5, 10 and 15 bar and injection pressures of 600 and 800 bar. Sauter mean diameter (SMD) values were estimated by using an analytical correlation. Consequently, ethyl esters performed longer SPL (2.8–20%) and narrower SCA (5.1–19%) than diesel under ambient pressures of 5 and 10 bar. Although the SMD values of ethyl esters were 48% higher than diesel on average, their macroscopic spray characteristics were very similar to those of diesel under 15 bar chamber pressure. Moreover, ethyl esters were found to be very similar to methyl esters in terms of spray characteristics. The differences in SPL, SCA and SMD values for both types of biodiesels were lower than 4%. When considering the uncertainty (± 0.84%) and repeatability (±5%) ratios, the difference between the spray characteristics of methyl and ethyl esters was not major. Graphical abstract: [Figure not available: see fulltext.] © 2022, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{ISI:000581901200009,
title = {Performance Analysis of Thermal Storage Assisted Cooling Tower with
Night Cooling},
author = {Kasim Toprak and Kiswendsida Elias Ouedraogo},
issn = {1302-0900},
year = {2020},
date = {2020-12-01},
journal = {JOURNAL OF POLYTECHNIC-POLITEKNIK DERGISI},
volume = {23},
number = {4},
pages = {1027-1035},
abstract = {As global warming and water scarcity issues continue to grow, it is
essential to increase resources efficiency for air conditioners and
power plants. In order to increase the efficiency, the systems need to
be modified to take the advantages of the low night temperature and
thermal storage tanks. In this study, the low night temperature and
thermal storage tanks effects on the cooling tower is studied using
TRNSYS. Using a chiller operating from 8:00 to 16:00 as a case study,
hot water from the condenser is partially stored on daytime and cooled
slowly during the night. The storage tank volume is optimized by
considering two big tanks and five small tanks. The results show that
night cooling reduces cooling water temperature by 5.8 degrees C or
21.8% while the cooling efficiency is increased by 36%. The thermal
storage tanks enable to have the low continuous flow rate and help to
reduce the fan power by 67.1%. On the storage side, compared to two
tanks system, the tanks volume is reduced by 16.5% when 5 tanks are
used. In theory this reduction can go up to 50% by increasing the
number of tanks and reducing their individual size.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Toprak20204366,
title = {Effect of storage tanks on solar-powered absorption chiller cooling system performance},
author = {K Toprak and K E Ouedraogo},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85079718680&doi=10.1002%2fer.5210&partnerID=40&md5=aa6c4b8eb29c64ec8849ffdd43934cc6},
doi = {10.1002/er.5210},
year = {2020},
date = {2020-01-01},
journal = {International Journal of Energy Research},
volume = {44},
number = {6},
pages = {4366-4375},
abstract = {Thermal storage, low power tariff at night, and low nocturnal temperature can be used in synergy to reduce the cooling costs of the solar-powered absorption chiller cooling systems. This study aims to reduce the required cooling capacity of an absorption chiller (ACH) powered by a solar parabolic trough collector (PTC) and a backup fuel boiler by integrating thermal storage tanks. The thermal performance of the system is simulated for a building that is cooled for 14 h/day. The system uses 1000 m2 PTC with 1020 kW ACH. Chilled water storage (CHWS) and cooling water storage (CWS) effects on the system performance for different operation hours per day of the ACH under Izmir (Turkey) and Phoenix (USA) weather conditions are analyzed. When the ACH operates 14 h/day as the load for both systems and both locations, the variations of the solar collector efficiency and the cooling load to heat input ratio remain less than 4% after the modifications. From the addition of CHWS to the reference system, a parametric study consisting of changing the ACH operation hours per day shows that the required cooling capacity of the ACH can be reduced to 34%. The capacity factor of the ACH is improved from its reference value of 41% up to 96%. © 2020 John Wiley & Sons Ltd},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Acarer2019137,
title = {Off-Design Analysis of Transonic Bypass Fan Systems Using Streamline Curvature Through-Flow Method},
author = {Sercan Acarer and Ünver Özkol},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85046815136&doi=10.1515%2ftjj-2016-0083&partnerID=40&md5=3b24de44dd45ff48c0814f96a18258cc},
doi = {10.1515/tjj-2016-0083},
year = {2019},
date = {2019-01-01},
journal = {International Journal of Turbo and Jet Engines},
volume = {36},
number = {2},
pages = {137 – 146},
abstract = {The two-dimensional streamline curvature through-flow modeling of turbomachinery is still a key element for turbomachinery preliminary analysis. Basically, axisymmetric swirling flow field is solved numerically. The effects of blades are imposed as sources of swirl, work input/output and entropy generation. Although the topic is studied vastly in the literature for compressors and turbines, combined modeling of the transonic fan and the downstream splitter of turbofan engine configuration, to the authors' best knowledge, is limited. In a prior study, the authors presented a new method for bypass fan modeling for inverse design calculations. Moreover, new set of practical empirical correlations are calibrated and validated. This paper is an extension of this study to rapid off-design analysis of transonic by-pass fan systems. The methodology is validated by two test cases: NASA 2-stage fan and GE-NASA bypass fan case. The proposed methodology is a simple extension for streamline curvature method and can be applied to existing compressor methodologies with minimum numerical effort. © 2019 Walter de Gruyter GmbH, Berlin/Boston.},
note = {All Open Access, Green Open Access},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Celik2019511,
title = {A study on numerical determination of permeability and inertia coefficient of aluminum foam using X-ray microtomography technique: Focus on inspection methods for reliability (permeability and inertia coefficient by tomography)},
author = {Hasan Celik and Moghtada Mobedi and Akira Nakayama and Unver Ozkol},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85065613946&doi=10.1615%2fJPorMedia.2019028887&partnerID=40&md5=cc89991bf14176783bc2c187db3358c8},
doi = {10.1615/JPorMedia.2019028887},
year = {2019},
date = {2019-01-01},
journal = {Journal of Porous Media},
volume = {22},
number = {5},
pages = {511 – 529},
abstract = {The volume-averaged (i.e., macroscopic) transport properties such as permeability and inertia coefficient of two aluminum foams with 10 and 20 pores per inch (PPI) pore density are found using microtomography images. It is shown that a comparison between the numerical values and the experimental results may not be sufficient to prove the correctness of the obtained results. Hence, in addition to traditional validation methods such as grid independency and comparison with reported results in literature, further inspections such as (a) checking the development of flow, (b) inspection of Darcy and non-Darcy regions, (c) conservation of flow rate through the porous media, (d) sufficiency of number of voxels in the narrow throats, and (e) observation of transverse velocity gradients in pores for high and low Reynolds numbers can be performed to further validate the achieved results. These techniques have been discussed and explained in detail for the performed study. Moreover, the obtained permeability and inertia coefficient values are compared with 19 reported theoretical, numerical, and experimental studies. The maximum deviation between the present results and the reported studies for 10 PPI is below 25%, while for 20 PPI it is below 28%. © 2019 by Begell House, Inc.},
note = {All Open Access, Green Open Access},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{ISI:000435491500001,
title = {Aerodynamic optimization of through-flow design model of a high by-pass
transonic aero-engine fan using genetic algorithm},
author = {Orcun Kor and Sercan Acarer and Unver Ozkol},
doi = {10.1177/0957650917730466},
issn = {0957-6509},
year = {2018},
date = {2018-05-01},
journal = {PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART A-JOURNAL OF
POWER AND ENERGY},
volume = {232},
number = {3},
pages = {211-224},
abstract = {This study deals with aerodynamic optimization of a high by-pass
transonic aero-engine fan module in a through-flow inverse design model
at cruise condition. To the authors' best knowledge, although the
literature contains through-flow optimization of the simplified cases of
compressors and turbines, an optimization study targeting the more
elaborate case of combined transonic fan and splitter through-flow model
is not considered in the literature. Such a through-flow optimization of
a transonic fan, combined with bypass and core streams separated by an
aerodynamically shaped flow splitter, possesses significant challenges
to any optimizer, due to highly non-linear nature of the problem and the
high number of constraints, including the fulfillment of the targeted
bypass ratio. It is the aim of this study to consider this previously
untouched area in detail and therefore present a more sophisticated and
accurate optimization environment for actual bypass fan systems. An
in-house optimization code using genetic algorithm is coupled with a
previously developed in-house through-flow solver which is using a
streamline curvature technique and a set of in-house calibrated
empirical models for incidence, deviation, loss and blockage. As the
through-flow models are the backbone of turbo-machinery design, and
great majority of design decisions are taken in this phase, such a study
is assessed to result in significant guidelines to the gas turbine
community.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Celik20181368,
title = {A numerical study on determination of volume averaged thermal transport properties of metal foam structures using X-ray microtomography technique},
author = {Hasan Celik and Moghtada Mobedi and Akira Nakayama and Unver Ozkol},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85057255888&doi=10.1080%2f10407782.2018.1494936&partnerID=40&md5=48bd8293534537dec7583acb2bf5c66f},
doi = {10.1080/10407782.2018.1494936},
year = {2018},
date = {2018-01-01},
journal = {Numerical Heat Transfer; Part A: Applications},
volume = {74},
number = {7},
pages = {1368 – 1386},
abstract = {Volume averaged thermal transport properties of two metal foams with 10 and 20 PPI are obtained by using microtomography technique. The digital 3D structures of samples are generated in computer environment. The governing equations are solved for the entire domain and the volume averaged technique is used to determine interfacial heat transfer coefficient, longitudinal and transverse thermal dispersion conductivity. The study is performed for the pore scale Reynolds number from 100 to 600. The obtained results are within the ranges of the suggested correlations in literature. The present study supports the correlations suggested by Calmidi and Mahajan (2000) and Zhang et al. (2016). © 2018, © 2018 Taylor & Francis Group, LLC.},
note = {All Open Access, Green Open Access},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{ISI:000416431600006b,
title = {A pore scale analysis for determination of interfacial convective heat
transfer coefficient for thin periodic porousmedia undermixed convection},
author = {Hasan Celik and Moghtada Mobedi and Oronzio Manca and Unver Ozkol},
doi = {10.1108/HFF-01-2017-0036},
issn = {0961-5539},
year = {2017},
date = {2017-01-01},
journal = {INTERNATIONAL JOURNAL OF NUMERICAL METHODS FOR HEAT & FLUID FLOW},
volume = {27},
number = {12},
pages = {2775-2798},
abstract = {Purpose - The purpose of this study is to determine interfacial
convective heat transfer coefficient numerically, for a porous media
consisting of square blocks in inline arrangement under mixed convection
heat transfer.
Design/methodology/approach - The continuity, momentum and energy
equations are solved in dimensionless form for a representative
elementary volume of porous media, numerically. The velocity and
temperature fields for different values of porosity, Ri and Re numbers
are obtained. The study is performed for the range of Ri number from
0.01 to 10, Re number from 100 to 500 and porosity value from 0.51 to
0.96. Based on the obtained results, the value of the interfacial
convective heat transfer coefficient is calculated by using volume
average method.
Findings - It was found that at low porosities (such as 0.51), the
interfacial Nusselt number does not considerably change with Ri and Re
numbers. However, for porous media with high Ri number and porosity
(such as 10 and 0.51, respectively), secondary flows occur in the middle
of the channel between rods improving heat transfer between solid and
fluid, considerably. It is shown that the available correlations of
interfacial heat transfer coefficient suggested for forced convection
can be used for mixed convection for the porous media with low porosity
(such as 0.51) or for the flow with low Ri number (such as 0.01).
Originality/value - To the best of the authors' knowledge, there is no
study on determination of interfacial convective heat transfer
coefficient for mixed convection in porous media in literature. The
present study might be the first study providing an accurate idea on the
range of this important parameter, which will be useful particularly for
researchers who study on mixed convection heat transfer in porous media,
macroscopically.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{ISI:000343781900056,
title = {Interfacial thermal resistance of Cu-SWCNT nanowire in water},
author = {Kasim Toprak and Yildiz Bayazitoglu},
doi = {10.1016/j.ijheatmasstransfer.2014.08.024},
issn = {0017-9310},
year = {2014},
date = {2014-12-01},
journal = {INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER},
volume = {79},
pages = {584-588},
abstract = {The conduction along the radial direction of CuNW-SWCNT nanocomposite
surrounded with water is examined. Due to its simplicity and
adaptability, a simple point-charge water model is implemented. Using
the Nose-Hoover thermostat, the copper core is kept at a uniform
temperature as a heat source, and a circular edge layer of water is kept
at a lower temperature as a heat sink in order to impose a radial
temperature distribution. The thermal boundary resistance was predicted
as 0.1732 x 10(8) m(2) K/W at the interface of CuNW-water, 3.16 x 10(-8)
m(2) K/W at the interface of SWCNT-water, and 0.743 x 10(-8) m(2) K/W at
the interface of (CuNW-SWCNT)-water. (C) 2014 Elsevier Ltd. All rights
reserved.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{ISI:000337224100010,
title = {DETERMINATION OF KOZENY CONSTANT BASED ON POROSITY AND PORE TO THROAT
SIZE RATIO IN POROUS MEDIUM WITH RECTANGULAR RODS},
author = {Turkuler Ozgumus and Moghtada Mobedi and Unver Ozkol},
doi = {10.1080/19942060.2014.11015516},
issn = {1994-2060},
year = {2014},
date = {2014-06-01},
journal = {ENGINEERING APPLICATIONS OF COMPUTATIONAL FLUID MECHANICS},
volume = {8},
number = {2},
pages = {308-318},
abstract = {Kozeny-Carman permeability equation is an important relation for the
determination of permeability in porous media. In this study, the
permeabilities of porous media that contains rectangular rods are
determined, numerically. The applicability of Kozeny-Carman equation for
the periodic porous media is investigated and the effects of porosity
and pore to throat size ratio on Kozeny constant are studied. The
continuity and Navier-Stokes equations are solved to determine the
velocity and pressure fields in the voids between the rods. Based on the
obtained flow field, the permeability values for different porosities
from 0.2 to 0.9 and pore to throat size ratio values from 1.63 to 7.46
are computed. Then Kozeny constants for different porous media with
various porosity and pore to throat size ratios are obtained and a
relationship between Kozeny constant, porosity and pore to throat size
ratio is constructed. The study reveals that the pore to throat size
ratio is an important geometrical parameter that should be taken into
account for deriving a correlation for permeability. The suggestion of a
fixed value for Kozeny constant makes the application of Kozeny-Carman
permeability equation too narrow for a very specific porous medium.
However, it is possible to apply the Kozeny-Carman permeability equation
for wide ranges of porous media with different geometrical parameters
(various porosity, hydraulic diameter, particle size and aspect ratio)
if Kozeny constant is a function of two parameters as porosity and pore
to throat size ratios.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{ISI:000318260200018,
title = {Numerical modeling of a CNT-Cu coaxial nanowire in a vacuum to determine
the thermal conductivity},
author = {K Toprak and Y Bayazitoglu},
doi = {10.1016/j.ijheatmasstransfer.2013.01.082},
issn = {0017-9310},
year = {2013},
date = {2013-06-01},
journal = {INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER},
volume = {61},
pages = {172-175},
abstract = {A molecular dynamics simulation is created to predict the thermal
conductivity of a (7,7) single wall carbon nanotube filled with a copper
nanowire for lengths ranging from 9.957 nm to 63.091 nm. In the
simulations, a temperature difference is created using Nose-Hoover
thermostats at the two ends with 320 K and 280 K. The thermal
conductivity of the carbon nanotube-copper nanowire nanostructure is
calculated to be 24% higher than that of a corresponding pure single
wall carbon nanotube and estimated to be 40% lower than that of a pure
copper nanowire. (C) 2013 Elsevier Ltd. All rights reserved.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{ISI:000329612200001,
title = {Thermal Dispersion in Porous Media-A Review on the Experimental Studies
for Packed Beds},
author = {Turkuler Ozgumus and Moghtada Mobedi and Unver Ozkol and Akira Nakayama},
doi = {10.1115/1.4024351},
issn = {0003-6900},
year = {2013},
date = {2013-05-01},
journal = {APPLIED MECHANICS REVIEWS},
volume = {65},
number = {3},
abstract = {Thermal dispersion is an important topic in the convective heat transfer
in porous media. In order to determine the heat transfer in a packed
bed, the effective thermal conductivity including both stagnant and
dispersion thermal conductivities should be known. Several theoretical
and experimental studies have been performed on the determination of the
effective thermal conductivity. The aim of this study is to review the
experimental studies done on the determination of the effective thermal
conductivity of the packed beds. In this study, firstly brief
information on the definition of the thermal dispersion is presented and
then the reported experimental studies on the determination of the
effective thermal conductivity are summarized and compared. The reported
experimental methods are classified into three groups: (1) heat
addition/removal at the lateral boundaries, (2) heat addition at the
inlet/outlet boundary, (3) heat addition inside the bed. For each
performed study, the experimental details, methods, obtained results,
and suggested correlations for the determination of the effective
thermal conductivity are presented. The similarities and differences
between experimental methods and reported studies are shown by tables.
Comparison of the correlations for the effective thermal conductivity is
made by using figures and the results of the studies are discussed.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{ISI:000272877900012,
title = {Visualization of diffusion and convection heat transport in a square
cavity with natural convection},
author = {Moghtada Mobedi and Uenver Ozkol and Bengt Sunden},
doi = {10.1016/j.ijheatmasstransfer.2009.09.048},
issn = {0017-9310},
year = {2010},
date = {2010-01-01},
journal = {INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER},
volume = {53},
number = {1-3},
pages = {99-109},
abstract = {In this study, the total heatfunction equation which includes diffusion
and convection transport is divided into the corresponding heatfunction
equations. The superposition rule is used to obtain the mathematical
definitions of diffusion and convection heatfunctions and corresponding
boundary conditions. It is observed that the separate visualization of
diffusion and convection heatlines provides significant information on
understanding of the mechanism of heat transfer in a convective flow.
The direction of the diffusion and convection heat transport as well as
the strength of convection compared to the conduction in entire or in a
portion of a domain can be visualized. The diffusion heatlines
demonstrate a potential flow like behavior while convective heat flow
rotates due to the source term of the convection heatfunction equation,
similar to the rotation of fluid flow generated by fluid flow vorticity.
The similarity between the streamfunction and the total heatfunction
yields a concept of heat flow vorticity, Omega(t). The obtained results
show that the maximum absolute value of the convection heatfunction may
be an appropriate parameter for determination of the convection
strength. The diffusion and convection heatfunction equations for
natural convection in a differentially heated square cavity for four
different length of the heated surface on the right vertical wall as s(p) = L/4, L/2, 3L/4 and L and a fixed length of the cooled surface on
the right vertical wall as L/4 are obtained and corresponding heatlines
are drawn. The values of the conduction heatfunction are positive while
the sign of convection heatfunction values is negative for the studied
cases. Based on the distribution of total heatlines, two regions are
detected in the cavity, an active region with the positive values of
heatlines signifying dominant conduction heat transfer and a passive
region with the negative heatfunction values in where convection heat
flow is dominant and heat only rotates in a closed contour pattern. The
variations of average Nusselt number, average of heat flow vorticity.
maximum absolute values of convection heatfunction and streamfunction at
different Rayleigh numbers and lengths of the heated surface are
presented. (C) 2009 Elsevier Ltd. All rights reserved.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}