Laminar natural convection in a fully partitioned enclosure containing fluid with nonlinear thermophysical properties

Cuckovic-Dzodzo, D.M.; Dzodzo, Milorad B.; Pavlović, Marijana R. Pantović

doi:10.1016/s0142-727x(99)00053-3

Cited by 44 publications

(9 citation statements)

References 28 publications

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“…For validation purposes, the present modelling and numerical approach was used to replicate several studies from the literature involving buoyancy-driven flows in enclosures (Soong et al 1996;Wang and Hamed 2006;Vivek et al 2012;Cuckovic-Dzodzo et al 1999;Corcione 2003;Davis 1983) as well as external convective flows over flat plates (Çengel 2007;Coulson et al 1999;Lienhard and Lienhard 2003) and radiant heat exchange between plates (Çengel 2007). Table 3 shows a summary of the average Nusselt numbers obtained for buoyancy-driven flows in enclosures with several aspect ratios (in the range 1-4) and Rayleigh numbers (in the range 10 3 -10 6 ).…”

Section: Validation Of Modelling Approachmentioning

confidence: 99%

Advanced modelling of the transport phenomena across horizontal clothing microclimates with natural convection

et al. 2015

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The ability of clothing to provide protection against external environments is critical for wearer's safety and thermal comfort. It is a function of several factors, such as external environmental conditions, clothing properties and activity level. These factors determine the characteristics of the different microclimates existing inside the clothing which, ultimately, have a key role in the transport processes occurring across clothing. As an effort to understand the effect of transport phenomena in clothing microclimates on the overall heat transport across clothing structures, a numerical approach was used to study the buoyancy-driven heat transfer across horizontal air layers trapped inside air impermeable clothing. The study included both the internal flow occurring inside the microclimate and the external flow occurring outside the clothing layer, in order to analyze the interdependency of these flows in the way heat is transported to/from the body. Two-dimensional simulations were conducted considering different values of microclimate thickness (8, 25 and 52 mm), external air temperature (10, 20 and 30 °C), external air velocity (0.5, 1 and 3 m s(-1)) and emissivity of the clothing inner surface (0.05 and 0.95), which implied Rayleigh numbers in the microclimate spanning 4 orders of magnitude (9 × 10(2)-3 × 10(5)). The convective heat transfer coefficients obtained along the clothing were found to strongly depend on the transport phenomena in the microclimate, in particular when natural convection is the most important transport mechanism. In such scenario, convective coefficients were found to vary in wavy-like manner, depending on the position of the flow vortices in the microclimate. These observations clearly differ from data in the literature for the case of air flow over flat-heated surfaces with constant temperature (which shows monotonic variations of the convective heat transfer coefficients, along the length of the surface). The flow patterns and temperature fields in the microclimates were found to strongly depend on the characteristics of the external boundary layer forming along the clothing and on the distribution of temperature in the clothing. The local heat transfer rates obtained in the microclimate are in marked contrast with those found in the literature for enclosures with constant-temperature active walls. These results stress the importance of coupling the calculation of the internal and the external flows and of the heat transfer convective and radiative components, when analyzing the way heat is transported to/from the body.

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Section: Validation Of Modelling Approachmentioning

confidence: 99%

Advanced modelling of the transport phenomena across horizontal clothing microclimates with natural convection

et al. 2015

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“…The left and right outer walls are held at fixed 'hot' and 'cold' temperatures respectively. Anderson & Bejan (1981) 6 10 9 < Ra < 10 10 0-2 0.33 Cuckovic-Dzodzo et al (1999) 2700-7000 10 4 < Ra < 10 6 0-1 1 Nishimura et al (1988) 6 10 8 < Ra < 10 10 0-4 4 Turkoglu & Yucel (1996) 0.71 10 5 < Ra < 10 7 0-4 0.5-1.5 Xu et al (2009) 7 1.8 × 10 9 0-1 1 The top and bottom walls are adiabatic and the central vertical wall has an infinite conductivity. In fully developed flow, natural convection boundary layers are formed on the vertical walls which flow onto the horizontal walls forming intrusions.…”

Section: Introductionmentioning

confidence: 99%

“…Typically the results are correlated with a Nusselt number relation of the form Nu ∼ Ra 1/4 (N + 1) −n where n is a constant coefficient and N is the number of partition walls (Anderson & Bejan 1981;Nishimura et al 1988;Turkoglu & Yucel 1996;Cuckovic-Dzodzo, Dzodzo & Pavlovic 1999;Xu, Patterson & Lei 2009). The parameter space covered by these studies is given in table 1.…”

Section: Introductionmentioning

confidence: 99%

Transition to oscillatory flow in a differentially heated cavity with a conducting partition

2011

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Numerical evidence is presented for previously unreported flow behaviour in a twodimensional rectangular side-heated cavity partitioned in the centre by vertical wall with an infinite conductivity. In this flow heat is transferred between both sides of the cavity through the conducting wall with natural convection boundary layers forming on all vertical surfaces. Simulations have been conducted over the range of Rayleigh numbers Ra = 0.6-1.6 × 10 10 at Prandtl number Pr = 7.5 and at aspect ratios of H/W = 1-2 where H and W are the height and width of the cavity. It was found that the thermal coupling of the boundary layers on either side of the conducting partition causes the cavity flow to become absolutely unstable for a Rayleigh number at which otherwise similar non-partitioned cavity flow is steady but convectively unstable. Additionally, unlike the non-partitioned cavity, which eventually bifurcates to a multimodal oscillatory regime, this bifurcation is manifested as a single mode oscillation with f + = f ν 1/3 / (gβ θ ) 2/3 ≈ 0.0145, where θ is the temperature difference between the hot and cold walls, g is the gravitational acceleration, f is the oscillation frequency and ν and β are the fluid viscosity and coefficient of thermal expansion respectively. The critical Rayleigh number for this transition occurs between Ra = 1.0-1.2 × 10 10 for H/W = 2 and Ra = 1.2-1.4 × 10 10 for H/W = 1, indicating that the instability has an aspect ratio dependence.

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“…number (Cuckovic-Dzodzo et al, 1999) does not depend on the flow rate. According to information from the literature, the dependence with such properties is new and the presence of this parameter in the exponent of the analytical expression (Eq.…”

Section: Resultsmentioning

confidence: 88%

Learning the Malay Traditional Musical Instruments by using Augmented Reality Application

Paranuk¹,

Kushtanok²,

Bunyakin³

et al. 2020

J. Eng. Appl. Sci.

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The study presents a mathematical model of temperature distribution for a gas flow in a pipeline with heat exchange through the wall. Modeling is performed in a one-dimensional (hydraulic) approximation but the temperature distribution across the pipe near its wall (thermal boundary layer) is taken into account. This model includes two independent parameters that contain information about the heat-conducting properties of gas and pipe walls, taking into account thermal insulation. The resulting equation is proposed for use for field gathering plumes. The parameter that includes the heat transfer coefficient through the pipe wall, when setting the task of determining the moment of the beginning of hydrate formation in the field plumes is not known in advance and is subject to identification by comparing the calculation data with the measurement information. To solve such (inverse) problems, an analytical form of representation of the dependencies between the process parameters is important which determines the relevance of the presented result. The novelty lies in the fact that the obtained analytical dependence for the temperature distribution along the pipeline describes the heat transfer through the wall (through the thermal boundary layer), the thermal conductivity inside the gas and the convective heat transfer along the flow.

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Laminar natural convection in a fully partitioned enclosure containing fluid with nonlinear thermophysical properties

Cited by 44 publications

References 28 publications

Advanced modelling of the transport phenomena across horizontal clothing microclimates with natural convection

Advanced modelling of the transport phenomena across horizontal clothing microclimates with natural convection

Transition to oscillatory flow in a differentially heated cavity with a conducting partition

Learning the Malay Traditional Musical Instruments by using Augmented Reality Application

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