Effect of aspect ratio on thermal convection in open and closed systems

Gregory Cartland-Glover, Kaoru Fujimura, Sotos Generalis

Research output: Contribution to conferenceAbstract

Abstract

Internally heated fluids are found across the nuclear fuel cycle. In certain situations the motion of the fluid is driven by the decay heat (i.e. corium melt pools in severe accidents, the shutdown of liquid metal reactors, molten salt and the passive control of light water reactors) as well as normal operation (i.e. intermediate waste storage and generation IV reactor designs). This can in the long-term affect reactor vessel integrity or lead to localized hot spots and accumulation of solid wastes that may prompt local increases in activity.
Two approaches to the modeling of internally heated convection are presented here. These are based on numerical analysis using codes developed in-house and simulations using widely available computational fluid dynamics solvers.
Open and closed fluid layers at around the transition between conduction and convection of various aspect ratios are considered. We determine optimum domain aspect ratio (1:7:7 up to 1:24:24 for open systems and 5:5:1, 1:10:10 and 1:20:20 for closed systems), mesh resolutions and turbulence models required to accurately and efficiently capture the convection structures that evolve when perturbing the conductive state of the fluid layer. Note that the open and closed fluid layers we study here are bounded by a conducting surface over an insulating surface. Conclusions will be drawn on the influence of the periodic boundary conditions on the flow patterns observed. We have also examined the stability of the nonlinear solutions that we found with the aim of identifying the bifurcation sequence of these solutions en route to turbulence.
Original languageEnglish
Publication statusPublished - 12 May 2013
Event15th international meeting on Nuclear Reactor Thermal Hydraulics - Pisa, Italy
Duration: 12 May 201317 May 2013

Meeting

Meeting15th international meeting on Nuclear Reactor Thermal Hydraulics
Abbreviated titleNURETH-15
CountryItaly
CityPisa
Period12/05/1317/05/13

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Aspect ratio
Fluids
Light water reactors
Open systems
Nuclear fuels
Solid wastes
Turbulence models
Liquid metals
Flow patterns
Numerical analysis
Accidents
Computational fluid dynamics
Turbulence
Convection
Hot Temperature
Boundary conditions

Cite this

Cartland-Glover, G., Fujimura, K., & Generalis, S. (2013). Effect of aspect ratio on thermal convection in open and closed systems. Abstract from 15th international meeting on Nuclear Reactor Thermal Hydraulics, Pisa, Italy.
Cartland-Glover, Gregory ; Fujimura, Kaoru ; Generalis, Sotos. / Effect of aspect ratio on thermal convection in open and closed systems. Abstract from 15th international meeting on Nuclear Reactor Thermal Hydraulics, Pisa, Italy.
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Cartland-Glover, G, Fujimura, K & Generalis, S 2013, 'Effect of aspect ratio on thermal convection in open and closed systems' 15th international meeting on Nuclear Reactor Thermal Hydraulics, Pisa, Italy, 12/05/13 - 17/05/13, .

Effect of aspect ratio on thermal convection in open and closed systems. / Cartland-Glover, Gregory; Fujimura, Kaoru; Generalis, Sotos.

2013. Abstract from 15th international meeting on Nuclear Reactor Thermal Hydraulics, Pisa, Italy.

Research output: Contribution to conferenceAbstract

TY - CONF

T1 - Effect of aspect ratio on thermal convection in open and closed systems

AU - Cartland-Glover, Gregory

AU - Fujimura, Kaoru

AU - Generalis, Sotos

PY - 2013/5/12

Y1 - 2013/5/12

N2 - Internally heated fluids are found across the nuclear fuel cycle. In certain situations the motion of the fluid is driven by the decay heat (i.e. corium melt pools in severe accidents, the shutdown of liquid metal reactors, molten salt and the passive control of light water reactors) as well as normal operation (i.e. intermediate waste storage and generation IV reactor designs). This can in the long-term affect reactor vessel integrity or lead to localized hot spots and accumulation of solid wastes that may prompt local increases in activity. Two approaches to the modeling of internally heated convection are presented here. These are based on numerical analysis using codes developed in-house and simulations using widely available computational fluid dynamics solvers. Open and closed fluid layers at around the transition between conduction and convection of various aspect ratios are considered. We determine optimum domain aspect ratio (1:7:7 up to 1:24:24 for open systems and 5:5:1, 1:10:10 and 1:20:20 for closed systems), mesh resolutions and turbulence models required to accurately and efficiently capture the convection structures that evolve when perturbing the conductive state of the fluid layer. Note that the open and closed fluid layers we study here are bounded by a conducting surface over an insulating surface. Conclusions will be drawn on the influence of the periodic boundary conditions on the flow patterns observed. We have also examined the stability of the nonlinear solutions that we found with the aim of identifying the bifurcation sequence of these solutions en route to turbulence.

AB - Internally heated fluids are found across the nuclear fuel cycle. In certain situations the motion of the fluid is driven by the decay heat (i.e. corium melt pools in severe accidents, the shutdown of liquid metal reactors, molten salt and the passive control of light water reactors) as well as normal operation (i.e. intermediate waste storage and generation IV reactor designs). This can in the long-term affect reactor vessel integrity or lead to localized hot spots and accumulation of solid wastes that may prompt local increases in activity. Two approaches to the modeling of internally heated convection are presented here. These are based on numerical analysis using codes developed in-house and simulations using widely available computational fluid dynamics solvers. Open and closed fluid layers at around the transition between conduction and convection of various aspect ratios are considered. We determine optimum domain aspect ratio (1:7:7 up to 1:24:24 for open systems and 5:5:1, 1:10:10 and 1:20:20 for closed systems), mesh resolutions and turbulence models required to accurately and efficiently capture the convection structures that evolve when perturbing the conductive state of the fluid layer. Note that the open and closed fluid layers we study here are bounded by a conducting surface over an insulating surface. Conclusions will be drawn on the influence of the periodic boundary conditions on the flow patterns observed. We have also examined the stability of the nonlinear solutions that we found with the aim of identifying the bifurcation sequence of these solutions en route to turbulence.

M3 - Abstract

ER -

Cartland-Glover G, Fujimura K, Generalis S. Effect of aspect ratio on thermal convection in open and closed systems. 2013. Abstract from 15th international meeting on Nuclear Reactor Thermal Hydraulics, Pisa, Italy.