نتایج جستجو برای: convection

تعداد نتایج: 26492  

2005
VALLE LÓPEZ JAVIER RUIZ

Recent investigations into convection in Europa’s ice shell have been based on nonNewtonian (stress-dependent) or Newtonian (stress-independent) viscosity for water ice. However, despite the wide use of Newtonian convection, experimentally observed water ice flow is non-Newtonian, and analysis of stability against convection of the ice shell using updated flow laws has been only performed for n...

2004
Garrett M. Leahy David Bercovici

[1] The ‘‘transition zone water filter’’ model of mantle convection attempts to reconcile geochemical evidence for isolated mantle reservoirs with geophysical evidence for whole mantle circulation by decoupling incompatible elements from bulk mantle circulation via a melt layer above the 410 km discontinuity. This would result in a stratified heating distribution similar to layered convection m...

Journal: :Physical review letters 2014
Robert E Ecke Joseph J Niemela

We report experimental measurements of heat transport in rotating Rayleigh-Bénard convection in a cylindrical convection cell with an aspect ratio of Γ=1/2. The fluid is helium gas with a Prandtl number Pr=0.7. The range of control parameters for Rayleigh numbers 4×10^{9}<Ra<4×10^{11} and for Ekman numbers 2×10^{-7}<Ek<3×10^{-5} (corresponding to Taylor numbers 4×10^{9}<Ta<1×10^{14} and convect...

2003
Jun Korenaga Thomas H. Jordan

[1] We investigate the physics of multiscale convection in Earth’s mantle, characterized by the coexistence of large-scale mantle circulation associated with plate tectonics and small-scale sublithospheric convection. In this study, conditions for the existence of smallscale convection beneath oceanic lithosphere are investigated by deriving a scaling law for the onset of convection in a fluid ...

2006
V. S. Solomatov A. C. Barr

The onset of convection in the power-law creep regime on the terrestrial planets and icy satellites is poorly constrained. The major difficulty is that the viscosity of power-law fluids approaches infinity when the perturbation amplitudes approach zero and thus the methods of linear theory are inapplicable. Here, we determine the critical Rayleigh number for the onset of convection by starting ...

2006
L. Han

We perform numerical simulations in 3D spherical geometry to study the properties of convection in Europa’s silicate mantle using the finite-element code CitcomS including temperature-dependent viscosity. Our simulations show that thermal convection occurs if the reference viscosity is – PaS, rheological activation energy is 150-300 kJ/mol, and the viscosity contrast (due to temperature variati...

Journal: :Tellus A: Dynamic Meteorology and Oceanography 1985

2007
A. Mezzacappa A. C. Calder S. W. Bruenn J. M. Blondin M. W. Guidry A. S. Umar

We couple two-dimensional hydrodynamics to detailed one-dimensional multigroup ux-limited diiusion neutrino transport to investigate prompt convection in core collapse supernovae. Our initial conditions, time-dependent boundary conditions, and neutrino distributions for computing neutrino heating, cooling, and deleptonization rates are obtained from one-dimensional simulations that implement mu...

Journal: :تحقیقات مهندسی کشاورزی 0
نیکروز باقری دانشجوی سابق کارشناسی ارشد علیرضا کیهانی دانشیار گروه مکانیک ماشین های کشاورزی دانشکده مهندسی و فناوری کشاورزی دانشگاه تهران سید سعید محتسبی استاد گروه مکانیک ماشین های کشاورزی دانشکده مهندسی و فناوری کشاورزی دانشگاه تهران رضا علیمرانی دانشیار گروه مکانیک ماشین های کشاورزی دانشکده مهندسی و فناوری کشاورزی دانشگاه تهران

monitoring the effective parameters of drying crops is necessary to evaluate and determine system performance under real conditions. hence, a monitoring system was constructed to determine the performance of a vegetation forced-convection solar dryer. digital temperature sensors were set up in the air inlet and outlet of the collector and the air outlet of the drying chamber. a program was writ...

Journal: :transport phenomena in nano and micro scales 2014
m. jafari m. farhadi k. sedighi

the effects of single walled carbon nanotube (swcnt) on mixed convection in a cavity are investigated numerically. the problem is studied for different richardson numbers (0.1-10), volume fractions of nanotubes (0-1%), and aspect ratio of the cavity (0.5-2.5) when the grashof number is equal to 103. the volume fraction of added nanotubes to water as base fluid are lowers than 1% to make dilute ...

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