Numerical study of a two-fluid hydrodynamic model of the interstellar medium and population I stars

1985 ◽  
Vol 297 ◽  
pp. 507 ◽  
Author(s):  
W.-H. Chiang ◽  
K. H. Prendergast
Keyword(s):  
Interstellar Medium ◽  
Hydrodynamic Model ◽  
Numerical Study ◽  
Two Fluid

scholarly journals A numerical study of the interaction between two ejecta in the interplanetary medium: one- and two-dimensional hydrodynamic simulations

2004 ◽  
Vol 22 (10) ◽  
pp. 3741-3749 ◽  
Author(s):  
A. Gonzalez-Esparza ◽  
A. Santillán ◽  
J. Ferrer
Keyword(s):  
Hydrodynamic Model ◽  
Physical Mechanism ◽  
Interplanetary Medium ◽  
Numerical Study ◽  
Two Dimensions ◽  
Magnetic Clouds ◽  
The Sun ◽  
Two Dimensional ◽  
Hydrodynamic Simulations

Abstract. We studied the heliospheric evolution in one and two dimensions of the interaction between two ejecta-like disturbances beyond the critical point: a faster ejecta 2 overtaking a previously launched slower ejecta 1. The study is based on a hydrodynamic model using the ZEUS-3-D code. This model can be applied to those cases where the interaction occurs far away from the Sun and there is no merging (magnetic reconnection) between the two ejecta. The simulation shows that when the faster ejecta 2 overtakes ejecta 1 there is an interchange of momentum between the two ejecta, where the leading ejecta 1 accelerates and the tracking ejecta 2 decelerates. Both ejecta tend to arrive at 1AU having similar speeds, but with the front of ejecta 1 propagating faster than the front of ejecta 2. The momentum is transferred from ejecta 2 to ejecta 1 when the shock initially driven by ejecta 2 passes through ejecta 1. Eventually the two shock waves driven by the two ejecta merge together into a single stronger shock. The 2-D simulation shows that the evolution of the interaction can be very complex and there are very different signatures of the same event at different viewing angles; however, the transferring of momentum between the two ejecta follows the same physical mechanism described above. These results are in qualitative agreement with in-situ plasma observations of "multiple magnetic clouds" detected at 1AU.

scholarly journals Numerical Study of Shear Banding in Flows of Fluids Governed by the Rolie-Poly Two-Fluid Model via Stabilized Finite Volume Methods

Processes ◽  
2020 ◽  
Vol 8 (7) ◽  
pp. 810
Author(s):  
Jade Gesare Abuga ◽  
Tiri Chinyoka
Keyword(s):  
Finite Volume ◽  
Numerical Algorithm ◽  
Numerical Study ◽  
Fluid Model ◽  
Shear Banding ◽  
Numerical Algorithms ◽  
Viscoelastic Fluids ◽  
Two Fluid Model ◽  
Two Fluid ◽  
Good Agreement

The flow of viscoelastic fluids may, under certain conditions, exhibit shear-banding characteristics that result from their susceptibility to unusual flow instabilities. In this work, we explore both the existing shear banding mechanisms in the literature, namely; constitutive instabilities and flow-induced inhomogeneities. Shear banding due to constitutive instabilities is modelled via either the Johnson–Segalman or the Giesekus constitutive models. Shear banding due to flow-induced inhomogeneities is modelled via the Rolie–Poly constitutive model. The Rolie–Poly constitutive equation is especially chosen because it expresses, precisely, the shear rheometry of polymer solutions for a large number of strain rates. For the Rolie–Poly approach, we use the two-fluid model wherein the stress dynamics are coupled with concentration equations. We follow a computational analysis approach via an efficient and versatile numerical algorithm. The numerical algorithm is based on the Finite Volume Method (FVM) and it is implemented in the open-source software package, OpenFOAM. The efficiency of our numerical algorithms is enhanced via two possible stabilization techniques, namely; the Log-Conformation Reformulation (LCR) and the Discrete Elastic Viscous Stress Splitting (DEVSS) methodologies. We demonstrate that our stabilized numerical algorithms accurately simulate these complex (shear banded) flows of complex (viscoelastic) fluids. Verification of the shear-banding results via both the Giesekus and Johnson-Segalman models show good agreement with existing literature using the DEVSS technique. A comparison of the Rolie–Poly two-fluid model results with existing literature for the concentration and velocity profiles is also in good agreement.

Deposition of Small Particles From Turbulent Flows

2003 ◽  
Author(s):  
Z. Wu ◽  
J. B. Young
Keyword(s):  
Turbulent Flow ◽  
Turbulent Flows ◽  
Channel Flow ◽  
Gas Turbines ◽  
Particle Deposition ◽  
Numerical Study ◽  
Turbulent Channel Flow ◽  
Brownian Diffusion ◽  
Small Particles ◽  
Two Fluid

This paper deals with particle deposition onto solid walls from turbulent flows. The aim of the study is to model particle deposition in industrial flows, such as the one in gas turbines. The numerical study has been carried out with a two fluid approach. The possible contribution to the deposition from Brownian diffusion, turbulent diffusion and shear-induced lift force are considered in the study. Three types of turbulent two-phase flows have been studied: turbulent channel flow, turbulent flow in a bent duct and turbulent flow in a turbine blade cascade. In the turbulent channel flow case, the numerical results from a two-dimensional code show good agreement with numerical and experimental results from other resources. Deposition problem in a bent duct flow is introduced to study the effect of curvature. Finally, the deposition of small particles on a cascade of turbine blades is simulated. The results show that the current two fluid models are capable of predicting particle deposition rates in complex industrial flows.

scholarly journals Inundation of the Ziltendorfer Lowland during the Odra flood 1997 and its impact on the main river – a numerical study

2006 ◽  
Vol 8 (3) ◽  
pp. 181-192 ◽  
Author(s):  
Hilmar Messal ◽  
Heinz-Theo Mengelkamp
Keyword(s):  
Water Level ◽  
Hydrodynamic Model ◽  
Numerical Study ◽  
Complex Flow ◽  
Dam Breach ◽  
Main River ◽  
Flooding Event ◽  
Odra River ◽  
Flooding Period ◽  
Good Agreement

The inundation of the Ziltendorfer Lowland, a farmland polder with some villages, during the major flooding event in July 1997 in the Odra watershed, is simulated with the two-dimensional hydrodynamic model TRIM2D. Inflow and outflow through three consecutive embankment breaches make up a complex flow regime which governs the inundation and the water level in the Odra river. With reasonable assumptions for the dam breach genesis the inundation and depletion are simulated in good agreement with the observed flooding front positions. Simulations with a one-dimensional hydrodynamic model for “dam breach” and “no dam breach” scenarios confirm analytical considerations of an increase of the water level downstream in the main river for the “dam breach” scenario because of an outflow from the Ziltendorfer Lowland into the Odra river during the peak flooding period.

A NUMERICAL STUDY OF TWO-PHASE FLOW USING A TWO-DIMENSIONAL TWO-FLUID MODEL

2004 ◽  
Vol 45 (10) ◽  
pp. 1049-1066 ◽  
Author(s):  
Moon-Sun Chung ◽  
Seung-Kyung Pak ◽  
Keun-Shik Chang
Keyword(s):  
Two Phase Flow ◽  
Numerical Study ◽  
Fluid Model ◽  
Phase Flow ◽  
Two Dimensional ◽  
Two Phase ◽  
Two Fluid Model ◽  
Two Fluid
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