نتایج جستجو برای: bio convection

تعداد نتایج: 86962  

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 ...

Journal: :transport phenomena in nano and micro scales 2015
a. aghaei g.a. sheikhzadeh h.r. ehteram m. hajiahmadi

natural convection heat transfer has many applications in different fields of industry; such as cooling industries, electronic transformer devices and ventilation equipment; due to simple process, economic advantage, low noise and renewed retrieval. recently, heat transfer of nanofluids have been considered because of higher thermal conductivity coefficient compared with those of ordinary fluid...

Journal: :جغرافیا و توسعه ناحیه ای 0
مشکواتی مشکواتی مزرعه فراهانی مزرعه فراهانی قندهاری قندهاری جعفری جعفری

due to its complexity and destructive nature, convection has been subject of many studies and researches among weather phenomena throughout the world. scientists have attempted for decades to generate different types of models to provide the possibility of abating or, at least, reducing convective weather phenomena effects on people’s lives. in south or southwest of iran, people are familiar wi...

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