Phase Asynchronous AMR Execution for Productive and Performant Astrophysical Flows

2018 ◽  
Author(s):  
Muhammad Nufail Farooqi ◽  
Tan Nguyen ◽  
Weiqun Zhang ◽  
Ann S. Almgren ◽  
John Shalf ◽  
...  
Keyword(s):  
Astrophysical Flows

Laboratory experiments to study supersonic astrophysical flows interacting with clumpy environments

2008 ◽  
pp. 101-105
Author(s):  
P. A. Rosen ◽  
J. M. Foster ◽  
B. H. Wilde ◽  
P. Hartigan ◽  
B. E. Blue ◽  
...  
Keyword(s):  
Laboratory Experiments ◽  
Astrophysical Flows

scholarly journals Perturbation dynamics in Keplerian flow under external stochastic forcing

2020 ◽  
Vol 492 (4) ◽  
pp. 5366-5376 ◽  
Author(s):  
D N Razdoburdin
Keyword(s):  
Reynolds Number ◽  
Angular Momentum ◽  
Momentum Transfer ◽  
Reynolds Numbers ◽  
Stochastic Forcing ◽  
Stochastic Force ◽  
Angular Momentum Transfer ◽  
Linear Perturbations ◽  
Average Angular Momentum ◽  
Astrophysical Flows

ABSTRACT We investigate the dynamics of linear perturbations in Keplerian flow under external stochastic force. To abstract from the details of flow structure and boundary conditions, we consider the problem in the shearing box approximation. An external force is assumed to have zero mean, even so, induced perturbations form a steady state, which provides angular momentum transfer to the periphery of the flow. The most effective scenario is based on the transient amplification of induced vortices with the following emission of a shearing sound wave, wherein the maximum of the flux linearly depends on Reynolds number. Thus such a mechanism is significant for astrophysical flows, for which enormous Reynolds numbers are typical. At the same time, addressing the problem analytically, we find that for incompressible fluid in the shearing box approximation stochastic forcing does not lead to average angular momentum transfer. Thus the compressibility of the fluid plays an important role here, and one cannot neglect it.

Simulation of astrophysical flows in isentropic approximation

2018 ◽  
Vol 27 (10) ◽  
pp. 1844014
Author(s):  
S. G. Moiseenko ◽  
G. S. Bisnovatyi-Kogan
Keyword(s):  
Shock Wave ◽  
Kinetic Energy ◽  
Energy Conservation ◽  
Conservation Equation ◽  
Numerical Errors ◽  
Energy Conservation Equation ◽  
Different Types ◽  
Entropy Conservation ◽  
Isentropic Approximation ◽  
Astrophysical Flows

One of the difficulties of numerical simulations of cold supersonic astrophysical flows is a big difference in different types of energy. Gravitational and/or kinetic energy of the gas could be much larger than its internal energy. In such a case, it is possible to get large numerical errors in the simulations. To avoid this difficulty, conservation of entropy equation was used instead of energy conservation equation. The entropy conservation equation does not contain the gravitational and kinetic energy. The application of the isentropic set of equations is correct when the flow does not contain shocks or the amplitude of the shocks (shock wave Mach number) is not large. We estimate the violation of the energy conservation low when the “shock wave” is isentropic.

scholarly journals Numerical MHD codes for modeling astrophysical flows

New Astronomy ◽  
2016 ◽  
Vol 45 ◽  
pp. 60-76 ◽  
Author(s):  
A.V. Koldoba ◽  
G.V. Ustyugova ◽  
P.S. Lii ◽  
M.L. Comins ◽  
S. Dyda ◽  
...  
Keyword(s):  
Astrophysical Flows
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