The two fluid model of the helium film

1971 ◽  
Vol 325 (1563) ◽  
pp. 447-468 ◽  
Keyword(s):  
Critical Velocity ◽  
Fluid Model ◽  
Experimental Result ◽  
Natural Consequence ◽  
Helium Film ◽  
Two Fluid Model ◽  
New Criterion ◽  
Two Fluid ◽  
Superfluid Velocity

Motivated by the recent discovery that the thickness of a helium film is independent of its state of superflow, we have analysed the conditions under which the two fluid model is consistent with equilibrium between film and vapour. The experimental result is found to be a natural consequence of the requirements for equilibrium. In addition we find that waves in a moving film should be convected at approximately 1/2(p s lp) u s , where u s is the superfluid velocity. A new criterion for critical velocity is discovered and a new result is obtained for the attenuation of waves.

Comments on the article: ‘The two-fluid model of the helium film’

1973 ◽  
Vol 333 (1593) ◽  
pp. 261-263 ◽  
Keyword(s):  
Superfluid Helium ◽  
Fluid Model ◽  
Convection Velocity ◽  
Thermodynamic Approach ◽  
Helium Film ◽  
Helium Films ◽  
Third Sound ◽  
Superfluid Flow ◽  
Two Fluid Model ◽  
Two Fluid

It is argued that the thermodynamic approach used by Goodstein and Saffman in their theory of thin superfluid helium films is incorrect. Their theory does not explain Keller’s experiment. The value they obtained for the convection velocity of third sound in a film with superfluid flow is consequently unfounded theoretically. Their calculation of third sound attenuation is shown to be incomplete.

Transition of Bubbly Flow in Vertical Tubes: New Criteria Through CFD Simulation

2009 ◽  
Vol 131 (9) ◽  
Author(s):  
A. K. Das ◽  
P. K. Das ◽  
J. R. Thome
Keyword(s):  
Cfd Simulation ◽  
Fluid Model ◽  
Bubbly Flow ◽  
Transition Criteria ◽  
Balance Technique ◽  
Flow Through ◽  
Two Fluid Model ◽  
New Criterion ◽  
Vertical Tubes ◽  
Two Fluid

The two fluid model is used to simulate upward gas-liquid bubbly flow through a vertical conduit. Coalescence and breakup of bubbles have been accounted for by embedding the population balance technique in the two fluid model. The simulation enables one to track the axial development of the voidage pattern and the distribution of the bubbles. Thereby it has been possible to propose a new criterion for the transition from bubbly to slug flow regime. The transition criteria depend on (i) the breakage and coalescence frequency, (ii) the bubble volume count below and above the bubble size introduced at the inlet, and (iii) the bubble count histogram. The prediction based on the present criteria exhibits excellent agreement with the experimental data. It has also been possible to simulate the transition from bubbly to dispersed bubbly flow at a high liquid flow rate using the same model.

scholarly journals Natural modes of the two-fluid model of two-phase flow

2021 ◽  
Vol 33 (3) ◽  
pp. 033324
Author(s):  
Alejandro Clausse ◽  
Martín López de Bertodano
Keyword(s):  
Two Phase Flow ◽  
Fluid Model ◽  
Phase Flow ◽  
Two Phase ◽  
Natural Modes ◽  
Two Fluid Model ◽  
Two Fluid

Self-consistent hydrodynamic two-fluid model of vortex plasma

2021 ◽  
Vol 33 (3) ◽  
pp. 037116
Author(s):  
Victor L. Mironov
Keyword(s):  
Fluid Model ◽  
Self Consistent ◽  
Two Fluid Model ◽  
Two Fluid

scholarly journals Mathematical study on two-fluid model for flow of K–L fluid in a stenosed artery with porous wall

2021 ◽  
Vol 3 (4) ◽  
Author(s):  
R. Ponalagusamy ◽  
Ramakrishna Manchi
Keyword(s):  
Theoretical Study ◽  
Fluid Model ◽  
Porous Wall ◽  
Governing Equations ◽  
Rate Of Increase ◽  
Special Cases ◽  
Stenosed Artery ◽  
Flow Through ◽  
Two Fluid Model ◽  
Two Fluid

AbstractThe present communication presents a theoretical study of blood flow through a stenotic artery with a porous wall comprising Brinkman and Darcy layers. The governing equations describing the flow subjected to the boundary conditions have been solved analytically under the low Reynolds number and mild stenosis assumptions. Some special cases of the problem are also presented mathematically. The significant effects of the rheology of blood and porous wall of the artery on physiological flow quantities have been investigated. The results reveal that the wall shear stress at the stenotic throat increases dramatically for the thinner porous wall (i.e. smaller values of the Brinkman and Darcy regions) and the rate of increase is found to be 18.46% while it decreases for the thicker porous wall (i.e. higher values of the Brinkman and Darcy regions) and the rate of decrease is found to be 10.21%. Further, the streamline pattern in the stenotic region has been plotted and discussed.

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