scholarly journals A Hypothesis for the Redevelopment of Warm-Core Cyclones over Northern Australia

2008 ◽  
Vol 136 (10) ◽  
pp. 3863-3872 ◽  
Author(s):  
Kerry Emanuel ◽  
Jeff Callaghan ◽  
Peter Otto
Keyword(s):  
Heat Transfer ◽  
Thermal Diffusivity ◽  
Tropical Cyclones ◽  
Deep Layer ◽  
Heat Fluxes ◽  
Northern Australia ◽  
One Dimensional ◽  
Warm Core ◽  
Vertical Heat ◽  
Underlying Soil

Tropical cyclones moving inland over northern Australia are occasionally observed to reintensify, even in the absence of well-defined extratropical systems. Unlike cases of classical extratropical rejuvenation, such reintensifying storms retain their warm-core structure, often redeveloping such features as eyes. It is here hypothesized that the intensification or reintensification of these systems, christened agukabams, is made possible by large vertical heat fluxes from a deep layer of very hot, sandy soil that has been wetted by the first rains of the approaching systems, significantly increasing its thermal diffusivity. To test this hypothesis, simulations are performed with a simple tropical cyclone model coupled to a one-dimensional soil model. These simulations suggest that warm-core cyclones can indeed intensify when the underlying soil is sufficiently warm and wet and are maintained by heat transfer from the soil. The simulations also suggest that when the storms are sufficiently isolated from their oceanic source of moisture, the rainfall they produce is insufficient to keep the soil wet enough to transfer significant quantities of heat, and the storms then decay rapidly.

Combined Mode Heat Transfer Analysis Utilizing Radiation Scaling

1986 ◽  
Vol 108 (3) ◽  
pp. 626-632 ◽  
Author(s):  
H. Lee ◽  
R. O. Buckius
Keyword(s):  
Heat Transfer ◽  
Scaling Laws ◽  
Radiant Heat ◽  
Heat Fluxes ◽  
Heat Transfer Analysis ◽  
Incident Intensity ◽  
One Dimensional ◽  
Flow Problems ◽  
Combined Mode ◽  
Good Agreement

Scaling laws have been formulated to predict the radiant heat flux in anisotropically scattering, one-dimensional planar media [1, 2]. The radiation portion of the problem is reduced to an equivalent nonscattering problem by the scaling. The same scaling laws are applied to problems when radiation is combined with other modes of heat transfer, requiring the solution of the energy equation for a temperature profile. The average incident intensity is accurately scaled by a multilayer approach. Results presented for radiation/conduction and the thermally developing Poiseuille flow problems show very good agreement between exact and scaled solutions for heat fluxes and temperature distributions.

scholarly journals A Thermo-electric Apparatus for Thermal Diffusivity and Thermal Conductivity Measurements

Energies ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 4238 ◽  
Author(s):  
Zhang ◽  
Lin ◽  
Tsai ◽  
Wu ◽  
Wu
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Thermal Diffusivity ◽  
Heat Source ◽  
Experimental Results ◽  
Measurement Device ◽  
Thermo Electric ◽  
One Dimensional ◽  
Transfer Measurement ◽  
Heat Transfer Measurement

In this study, a one-dimensional heat transfer measurement device is developed based on the mathematical theory of the Angstrom method. To conform to the mathematical assumption, it is required that the device precisely controls the heat source to generate sinusoidal temperature signal. A thermo-electric module is used as the heat source for the measurement platform. This module is connected to a computer for program control, such that the temperature can be controlled quickly, precisely, and dynamically. In this study, five common heat-conducting materials are tested to verify the proposed one-dimensional heat transfer measurement device. By substituting the experimental results into the mathematical model of the Angstrom method, the thermal diffusion and thermal conductivity of the test material is calculated. The experimental results are compared with the physical properties of the materials, and the accuracy error is extremely low. This study confirmed that the Angstrom method theory applied thermal diffusivity and thermal conductivity measurement, which can be realized by thermo-electric temperature control technology.

scholarly journals Comparison of six algorithms to determine the soil thermal diffusivity at a site in the Loess Plateau of China

2009 ◽  
Vol 6 (2) ◽  
pp. 2247-2274 ◽  
Author(s):  
Z. Gao ◽  
L. Wang ◽  
R. Horton
Keyword(s):  
Heat Transfer ◽  
Heat Conduction ◽  
Thermal Diffusivity ◽  
Soil Temperature ◽  
Loess Plateau ◽  
One Dimensional ◽  
Boundary Temperature ◽  
Soil Thermal Diffusivity ◽  
Thermal Diffusivities ◽  
Upper Boundary

Abstract. Soil thermal diffusivity is a crucial physical parameter that affects soil temperature. Six prevalent algorithms to calculate soil thermal diffusivity are inter-compared by using soil temperature data collected at the depths of 0.05 m and 0.10 m at a bare site in the China Loess Plateau from DOY 201 through DOY 207 in 2005. Five of the six algorithms (i.e., Amplitude, Phase, Arctangent, Logarithm, and Harmonic or HM algorithms) are developed from the traditional one-dimensional heat conduction equation. The other algorithm is based on the one-dimensional heat conduction-convection equation which considers the vertical heterogeneity of thermal diffusivity in soil and couples thermal conduction and convection processes (hereinafter referred to as the Conduction-convection algorithm). To assess these six algorithms, we (1) calculate the soil thermal diffusivities by using each of the algorithms, (2) use the soil thermal diffusivities to predict soil temperature at the 0.10 m depth, and (3) compare the estimated soil temperature against direct measurements. Results show that (1) HM algorithm gives the most reliable estimates among the traditional five algorithms; and (2) generally, the Conduction-convection algorithm provides the second best estimates. Among all of the algorithms, the HM algorithm has the best description of the upper boundary temperature with time, but it only includes conduction heat transfer in the soil. Compared to the HM algorithm, the Conduction-convection algorithm has a less accurate description of the upper boundary temperature, but by accounting for the vertical gradient of soil diffusivity and the water flux density it includes more physics in the soil heat transfer process. The Conduction-convection algorithm has potential application within land surface models, but future effort should be made to combine the HM and Conduction-convection algorithms in order to make use of the advantages of each.

Improvement Of Free Convection From Three horizontal Finned Cylinders Fixed Between Two Walls

2018 ◽  
Vol 6 (2) ◽  
pp. 98-114 ◽  
Author(s):  
Hassan K. Abdullah ◽  
Haneen H. Rahman
Keyword(s):  
Heat Transfer ◽  
Free Convection ◽  
Prandtl Number ◽  
Convection Heat Transfer ◽  
Constant Heat Flux ◽  
Heat Fluxes ◽  
Head Orientation ◽  
Outer Diameter ◽  
Gravitational Acceleration ◽  
Convection Heat

Improvement of  free convection heat transfer from three finned cylinders arranged at a triangle shape fixed between two walls has been investigated in this study. Three mild steel finned cylinders fixed between two walls from Pyrex glass have been used as a test rig. It has been changed the spacing between the cylinders (X/D=1,2,3 & S/D=2,4,6) and the head orientation of a triangle to the top under constant heat flux values (38, 254, 660, 1268) W/m2 and compare with case of three finned cylinders arranged in vertical array in line fixed between two wall. The experiments are carried for Rayleigh number (Ra) from (15x103 to 14 x104 ) and Prandtl  number from (0.706-0.714 ). The results indicated an increase in Nu with increasing Ra for all cylinders. Furthermore,hx and Nu increased proportionally with the increasing of cylinder spacings for all heat fluxes. Also the experimental results show the case of triangle arrangement is improvement the heat transfer more than case of vertical arrangement. Heat transfer dimensionless correlating equation is also proposed.              Nomeclature: Ax: surface area(m2), T∞: surrounding temperature(k), D: the outer diameter of fin (m), Kf: the thermal conductivity for air at film temperature(W/m.k), hx: Local convection heat transfer(W/m2.k),  Gravitational acceleration(m/s2), I: Electric current (Amp), Nu: Nusselt number, Pr: Prandtl number

scholarly journals One-dimensional particle models for heat transfer analysis

2010 ◽  
Vol 260 ◽  
pp. 012005 ◽  
Author(s):  
H Bufferand ◽  
G Ciraolo ◽  
Ph Ghendrih ◽  
P Tamain ◽  
F Bagnoli ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Analysis ◽  
One Dimensional
Sign in / Sign up

Export Citation Format

Share Document