scholarly journals Numerical simulations of transonic flows with non-unique solutions

2021 ◽  
Vol 7 (2) ◽  
pp. 127
Author(s):  
A.M. Chuen ◽  
M. Hafez
Keyword(s):  
Numerical Simulations ◽  
Transonic Flows

Determination of the laminar-turbulent transition location in numerical simulations of subsonic and transonic flows past a flat plate

2019 ◽  
Vol 26 (5) ◽  
pp. 629-637 ◽  
Author(s):  
A. V. Boiko ◽  
K. V. Demyanko ◽  
A. A. Inozemtsev ◽  
S. V. Kirilovskiy ◽  
Yu. M. Nechepurenko ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Flat Plate ◽  
Transonic Flows ◽  
Turbulent Transition ◽  
Transition Location ◽  
Laminar Turbulent Transition

FUNDAMENTAL CONCEPTS IN TRANSONIC FLOW PARADIGM OF BLACK HOLE ASTROPHYSICS

2011 ◽  
Vol 20 (10) ◽  
pp. 1723-1731 ◽  
Author(s):  
SANDIP K. CHAKRABARTI
Keyword(s):  
Black Hole ◽  
Numerical Simulations ◽  
Transonic Flow ◽  
Transonic Flows ◽  
Accretion Flow ◽  
New Concepts ◽  
The Subject

Exactly three decades ago, it was realized that an accretion flow onto a black hole should be transonic. Since then, the subject has matured considerably and several new and well established concepts and methodologies have replaced earlier ways of studying accretion and winds. Not surprisingly, with the advent of the faster computers as well as better space-based telescopes, the results of numerical simulations and the observations have also improved along with the theory. Today, it is more than satisfying that the results of theory and numerical simulations, even in the context of nonmagnetic flows, agree in details of the observations exceedingly well. I present here several new concepts and intricacies which one has to get familiar with when one talks about the behavior of the transonic flows, either in accretion or in the outflows.

Direct Numerical Simulations of Gas–Liquid Multiphase Flows

2001 ◽  
Author(s):  
Grétar Tryggvason ◽  
Ruben Scardovelli ◽  
Stéphane Zaleski
Keyword(s):  
Numerical Simulations ◽  
Multiphase Flows ◽  
Direct Numerical Simulations

Saturation mechanism and generated viscosity in gravito-turbulent accretion disks

2020 ◽  
Vol 640 ◽  
pp. A53
Author(s):  
L. Löhnert ◽  
S. Krätschmer ◽  
A. G. Peeters
Keyword(s):  
Growth Rate ◽  
Numerical Simulations ◽  
Accretion Disks ◽  
Gravitational Instability ◽  
Turbulent Viscosity ◽  
Radial Distance ◽  
Maximum Growth ◽  
Wave Number ◽  
Radiative Cooling ◽  
Mixing Length

Here, we address the turbulent dynamics of the gravitational instability in accretion disks, retaining both radiative cooling and irradiation. Due to radiative cooling, the disk is unstable for all values of the Toomre parameter, and an accurate estimate of the maximum growth rate is derived analytically. A detailed study of the turbulent spectra shows a rapid decay with an azimuthal wave number stronger than ky−3, whereas the spectrum is more broad in the radial direction and shows a scaling in the range kx−3 to kx−2. The radial component of the radial velocity profile consists of a superposition of shocks of different heights, and is similar to that found in Burgers’ turbulence. Assuming saturation occurs through nonlinear wave steepening leading to shock formation, we developed a mixing-length model in which the typical length scale is related to the average radial distance between shocks. Furthermore, since the numerical simulations show that linear drive is necessary in order to sustain turbulence, we used the growth rate of the most unstable mode to estimate the typical timescale. The mixing-length model that was obtained agrees well with numerical simulations. The model gives an analytic expression for the turbulent viscosity as a function of the Toomre parameter and cooling time. It predicts that relevant values of α = 10−3 can be obtained in disks that have a Toomre parameter as high as Q ≈ 10.

CHARACTERIZATION OF SPLASH-PLATE ATOMIZERS USING NUMERICAL SIMULATIONS

2007 ◽  
Vol 17 (4) ◽  
pp. 347-380 ◽  
Author(s):  
Mohammad P. Fard ◽  
Denise Levesque ◽  
Stuart Morrison ◽  
Nasser Ashgriz ◽  
J. Mostaghimi
Keyword(s):  
Numerical Simulations
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