Comparative CFD modeling of a bubbling bed using a Eulerian–Eulerian two-fluid model (TFM) and a Eulerian-Lagrangian dense discrete phase model (DDPM)

2021 ◽  
Vol 383 ◽  
pp. 418-442
Author(s):  
Muhammad Adnan ◽  
Jie Sun ◽  
Nouman Ahmad ◽  
Jin Jia Wei
Keyword(s):  
Fluid Model ◽  
Phase Model ◽  
Cfd Modeling ◽  
Discrete Phase Model ◽  
Bubbling Bed ◽  
Discrete Phase ◽  
Two Fluid Model ◽  
Two Fluid

scholarly journals A Hybrid Eulerian–Eulerian Discrete-Phase Model of Turbulent Bubbly Flow

2018 ◽  
Vol 140 (10) ◽  
Author(s):  
Hyunjin Yang ◽  
Surya P. Vanka ◽  
Brian G. Thomas
Keyword(s):  
Bubble Size ◽  
Fluid Model ◽  
Bubbly Flow ◽  
Turbulent Dispersion ◽  
Phase Model ◽  
Discrete Phase Model ◽  
Size Change ◽  
Volumetric Expansion ◽  
Discrete Phase ◽  
Bubble Sizes

The Eulerian–Eulerian two-fluid model (EE) is a powerful general model for multiphase flow computations. However, one limitation of the EE model is that it has no ability to estimate the local bubble sizes by itself. In this work, we have combined the discrete phase model (DPM) to estimate the evolution of bubble sizes with the EE model. In the DPM, the change of bubble size distribution is estimated by coalescence, breakup, and volumetric expansion modeling of the bubbles. The time-varying bubble distribution is used to compute the local interface area between gas and liquid phase, which is then used to estimate the momentum interactions such as drag, lift, wall lubrication, and turbulent dispersion forces for the EE model. In this work, this newly developed hybrid model Eulerian–Eulerian discrete-phase model (EEDPM) is applied to compute an upward flowing bubbly flow in a vertical pipe and the results are compared with previous experimental work of Hibiki et al. (2001, “Axial Interfacial Area Transport of Vertical Bubbly Flows,” Int. J. Heat Mass Transfer, 44(10), pp. 1869–1888). The EEDPM model is able to reasonably predict the locally different bubble size distributions and the velocity and gas fraction fields. On the other hand, the standard EE model without the DPM shows good comparison with measurements only when the prescribed constant initial bubble size is accurate and does not change much. Parametric studies are implemented to understand the contributions of bubble interactions and volumetric expansion on the size change of bubbles quantitatively. The results show that coalescence is larger than other effects, and naturally increases in importance with increasing gas fraction.

scholarly journals Enhanced discrete phase model for multiphase flow simulation of blood flow with high shear stress

2021 ◽  
Vol 104 (1) ◽  
pp. 003685042110080
Author(s):  
Zheqin Yu ◽  
Jianping Tan ◽  
Shuai Wang
Keyword(s):  
Blood Flow ◽  
Shear Stress ◽  
Multiphase Flow ◽  
Experimental Verification ◽  
Flow Simulation ◽  
Turbulence Models ◽  
Phase Model ◽  
Force Model ◽  
Discrete Phase Model ◽  
Discrete Phase

Shear stress is often present in the blood flow within blood-contacting devices, which is the leading cause of hemolysis. However, the simulation method for blood flow with shear stress is still not perfect, especially the multiphase flow model and experimental verification. In this regard, this study proposes an enhanced discrete phase model for multiphase flow simulation of blood flow with shear stress. This simulation is based on the discrete phase model (DPM). According to the multiphase flow characteristics of blood, a virtual mass force model and a pressure gradient influence model are added to the calculation of cell particle motion. In the experimental verification, nozzle models were designed to simulate the flow with shear stress, varying the degree of shear stress through different nozzle sizes. The microscopic flow was measured by the Particle Image Velocimetry (PIV) experimental method. The comparison of the turbulence models and the verification of the simulation accuracy were carried out based on the experimental results. The result demonstrates that the simulation effect of the SST k- ω model is better than other standard turbulence models. Accuracy analysis proves that the simulation results are accurate and can capture the movement of cell-level particles in the flow with shear stress. The results of the research are conducive to obtaining accurate and comprehensive analysis results in the equipment development phase.

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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