Numerical study of a viscoelastic fluid in the output region of curved duct using a finite volume method

2013 ◽  
Author(s):  
T. Zambrano ◽  
G. Mompean ◽  
Z. Salloum
Keyword(s):  
Finite Volume Method ◽  
Finite Volume ◽  
Viscoelastic Fluid ◽  
Numerical Study ◽  
Curved Duct ◽  
Volume Method

scholarly journals Numerical study of a case of the free discharge of water through the turbine with a braked runner

2021 ◽  
Vol 2119 (1) ◽  
pp. 012152
Author(s):  
D V Platonov ◽  
A V Minakov ◽  
A V Sentyabov
Keyword(s):  
Finite Volume Method ◽  
Finite Volume ◽  
Numerical Study ◽  
Francis Turbine ◽  
Flow Structures ◽  
Pressure Pulsations ◽  
Integral Characteristics ◽  
Free Discharge ◽  
Simulation Results ◽  
Volume Method

Abstract The paper presents a numerical study of the free discharge of water through the turbine with a braked runner. The simulation was carried out for a unit of a full-scale Francis turbine. The finite volume method was employed for unstructured meshes using the DES method. The simulation results show the flow structures, integral characteristics, and pressure pulsations in the flow path. The analysis of the applicability of this approach to real conditions is carried out.

The Rheology of Blood Flow in a Branched Arterial System

2005 ◽  
Vol 15 (6) ◽  
pp. 398-405 ◽  
Author(s):  
Shewaferaw S. Shibeshi ◽  
William E. Collins
Keyword(s):  
Blood Flow ◽  
Finite Volume Method ◽  
Finite Volume ◽  
Power Law ◽  
Numerical Study ◽  
Arterial System ◽  
Magnitude Distribution ◽  
Velocity Magnitude ◽  
Percentage Difference ◽  
Volume Method

AbstractBlood flow rheology is a complex phenomenon. Presently there is no universally agreed upon model to represent the viscous property of blood. However, under the general classification of non-Newtonian models that simulate blood behavior to different degrees of accuracy, there are many variants. The power law, Casson and Carreau models are popular non-Newtonian models and affect hemodynamics quantities under many conditions. In this study, the finite volume method is used to investigate hemodynamics predictions of each of the models. To implement the finite volume method, the computational fluid dynamics software Fluent 6.1 is used. In this numerical study the different hemorheological models are found to predict different results of hemodynamics variables which are known to impact the genesis of atherosclerosis and formation of thrombosis. The axial velocity magnitude percentage difference of up to 2 % and radial velocity difference up to 90 % is found at different sections of the T-junction geometry. The size of flow recirculation zones and their associated separation and reattachment point’s locations differ for each model. The wall shear stress also experiences up to 12 % shift in the main tube. A velocity magnitude distribution of the grid cells shows that the Newtonian model is close dynamically to the Casson model while the power law model resembles the Carreau model.

Dynamics of high-Deborah-number entry flows: a numerical study

2011 ◽  
Vol 677 ◽  
pp. 272-304 ◽  
Author(s):  
A. M. AFONSO ◽  
P. J. OLIVEIRA ◽  
F. T. PINHO ◽  
M. A. ALVES
Keyword(s):  
Finite Volume Method ◽  
Finite Volume ◽  
Newtonian Fluid ◽  
Numerical Study ◽  
Chaotic Regime ◽  
Deborah Number ◽  
Weissenberg Number ◽  
Local Flow ◽  
Abrupt Contraction ◽  
Volume Method

High-elasticity simulations of flows through a two-dimensional (2D) 4 : 1 abrupt contraction and a 4 : 1 three-dimensional square–square abrupt contraction were performed with a finite-volume method implementing the log-conformation formulation, proposed by Fattal & Kupferman (J. Non-Newtonian Fluid Mech., vol. 123, 2004, p. 281) to alleviate the high-Weissenberg-number problem. For the 2D simulations of Boger fluids, modelled by the Oldroyd-B constitutive equation, local flow unsteadiness appears at a relatively low Deborah number (De) of 2.5. Predictions at higher De were possible only with the log-conformation technique and showed that the periodic unsteadiness grows with De leading to an asymmetric flow with alternate back-shedding of vorticity from pulsating upstream recirculating eddies. This is accompanied by a frequency doubling mechanism deteriorating to a chaotic regime at high De. The log-conformation technique provides solutions of accuracy similar to the thoroughly tested standard finite-volume method under steady flow conditions and the onset of a time-dependent solution occurred approximately at the same Deborah number for both formulations. Nevertheless, for Deborah numbers higher than the critical Deborah number, and for which the standard iterative technique diverges, the log-conformation technique continues to provide stable solutions up to quite (impressively) high Deborah numbers, demonstrating its advantages relative to the standard methodology. For the 3D contraction, calculations were restricted to steady flows of Oldroyd-B and Phan-Thien–Tanner (PTT) fluids and very high De were attained (De ≈ 20 for PTT with ϵ = 0.02 and De ≈ 10000 for PTT with ϵ = 0.25), with prediction of strong vortex enhancement. For the Boger fluid calculations, there was inversion of the secondary flow at high De, as observed experimentally by Sousa et al. (J. Non-Newtonian Fluid Mech., vol. 160, 2009, p. 122).

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