scholarly journals Nonlinear Simulations of the Heat-Flux-driven Buoyancy Instability and Its Implications for Galaxy Clusters

2008 ◽  
Vol 677 (1) ◽  
pp. L9-L12 ◽  
Author(s):  
Ian J. Parrish ◽  
Eliot Quataert
Keyword(s):  
Heat Flux ◽  
Galaxy Clusters ◽  
Nonlinear Simulations ◽  
Buoyancy Instability

scholarly journals Magnetorotational instability in cool cores of galaxy clusters

2015 ◽  
Vol 81 (5) ◽  
Author(s):  
Carlo Nipoti ◽  
L. Posti ◽  
S. Ettori ◽  
M. Bianconi
Keyword(s):  
Heat Flux ◽  
Heat Conduction ◽  
Galaxy Clusters ◽  
Magnetized Plasma ◽  
Radiative Cooling ◽  
Clusters Of Galaxies ◽  
Magnetorotational Instability ◽  
X Ray ◽  
Stability Properties ◽  
Anisotropic Heat Conduction

Clusters of galaxies are embedded in halos of optically thin, gravitationally stratified, weakly magnetized plasma at the system’s virial temperature. Owing to radiative cooling and anisotropic heat conduction, such intracluster medium (ICM) is subject to local instabilities, which are combinations of the thermal, magnetothermal and heat-flux-driven buoyancy instabilities. If the ICM rotates significantly, its stability properties are substantially modified and, in particular, also the magnetorotational instability (MRI) can play an important role. We study simple models of rotating cool-core clusters and we demonstrate that the MRI can be the dominant instability over significant portions of the clusters, with possible implications for the dynamics and evolution of the cool cores. Our results give further motivation for measuring the rotation of the ICM with future X-ray missions such as ASTRO-H and ATHENA.

Anisotropic dissipative effects on the buoyancy instability with background heat flux

2011 ◽  
Vol 18 (3) ◽  
pp. 032106
Author(s):  
Haijun Ren ◽  
Jintao Cao ◽  
Zhengwei Wu ◽  
Paul K. Chu
Keyword(s):  
Heat Flux ◽  
Dissipative Effects ◽  
Buoyancy Instability

Siphon Flows in Stratified Coronal Loops

1994 ◽  
Vol 144 ◽  
pp. 185-187
Author(s):  
S. Orlando ◽  
G. Peres ◽  
S. Serio
Keyword(s):  
Heat Flux ◽  
Scaling Laws ◽  
Flow Model ◽  
Supersonic Flows ◽  
Coronal Loops ◽  
Characteristic Parameters

AbstractWe have developed a detailed siphon flow model for coronal loops. We find scaling laws relating the characteristic parameters of the loop, explore systematically the space of solutions and show that supersonic flows are impossible for realistic values of heat flux at the base of the upflowing leg.

Rate of Sublimation of Ice by Radiative Heating in Freeze-Etching

1980 ◽  
Vol 38 ◽  
pp. 618-619
Author(s):  
Yeshayahu Talmon
Keyword(s):  
Heat Flux ◽  
Freeze Fracture ◽  
Constant Heat Flux ◽  
Radiative Heating ◽  
Constant Heat ◽  
Entire Sample ◽  
Simplified Method ◽  
Freeze Etching ◽  
Sublimation Rates ◽  
Fractured Surface

To bring out details in the fractured surface of a frozen sample in the freeze fracture/freeze-etch technique,the sample or part of it is warmed to enhance water sublimation.One way to do this is to raise the temperature of the entire sample to about -100°C to -90°C. In this case sublimation rates can be calculated by using plots such as Fig.1 (Talmon and Thomas),or by simplified formulae such as that given by Menold and Liittge. To achieve higher rates of sublimation without heating the entire sample a radiative heater can be used (Echlin et al.). In the present paper a simplified method for the calculation of the rates of sublimation under a constant heat flux F [W/m2] at the surface of the sample from a heater placed directly above the sample is described.

Mass distribution and Dynamical State of Galaxy Clusters in the LZLS Sample

2006 ◽  
Vol 20 ◽  
pp. 269-270 ◽  
Author(s):  
L.E. Campusano ◽  
E.S. Cypriano ◽  
L. Jr. Sodré ◽  
J.-P. Kneib
Keyword(s):  
Galaxy Clusters ◽  
Mass Distribution ◽  
Dynamical State

Numerical analysis of local heat flux and thin-slab solidification in a CSP funnel-type mold with electromagnetic braking

2020 ◽  
Vol 117 (6) ◽  
pp. 602
Author(s):  
Heping Liu ◽  
Jianjun Zhang ◽  
Hongbiao Tao ◽  
Hui Zhang
Keyword(s):  
Heat Flux ◽  
Casting Speed ◽  
Shell Growth ◽  
Local Heat ◽  
Operating Conditions ◽  
Thin Slab ◽  
Wide Face ◽  
Slab Width ◽  
Steel Grades ◽  
Local Heat Flux

In this article, based on the actual monitored temperature data from mold copper plate with a dense thermocouple layout and the measured magnetic flux density values in a CSP thin-slab mold, the local heat flux and thin-slab solidification features in the funnel-type mold with electromagnetic braking are analyzed. The differences of local heat flux, fluid flow and solidified shell growth features between two steel grades of Q235B with carbon content of 0.19%C and DC01 of 0.03%C under varying operation conditions are discussed. The results show the maximum transverse local heat flux is near the meniscus region of over 0.3 m away from the center of the wide face, which corresponds to the upper flow circulation and the large turbulent kinetic energy in a CSP funnel-type mold. The increased slab width and low casting speed can reduce the fluctuation of the transverse local heat flux near the meniscus. There is a decreased transverse local heat flux in the center of the wide face after the solidified shell is pulled through the transition zone from the funnel-curve to the parallel-cure zone. In order to achieve similar metallurgical effects, the braking strength should increase with the increase of casting speed and slab width. Using the strong EMBr field in a lower casting speed might reverse the desired effects. There exist some differences of solidified shell thinning features for different steel grades in the range of the funnel opening region under the measured operating conditions, which may affect the optimization of the casting process in a CSP caster.

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