Study of Blood Flow in Micro-Channels Using Mixture Theory

2014 ◽  
Author(s):  
Wei-Tao Wu ◽  
Nadine Aubry ◽  
James F. Antaki ◽  
Mehrdad Massoudi
Keyword(s):  
Blood Flow ◽  
Newtonian Fluid ◽  
Mixture Theory ◽  
Shear Thinning ◽  
Characteristic Size ◽  
Navier Stokes ◽  
Two Phase ◽  
Plasma Skimming ◽  
Micro Channels ◽  
Complex Phenomena

It is known that in large vessels (whole) blood behaves as a Navier-Stokes (Newtonian) fluid; however, in a vessel whose characteristic dimension (e.g., a diameter in the range of 20 to 500 microns) is about the same size as the characteristic size of the blood cells, blood behaves as a non-Newtonian fluid, exhibiting complex phenomena, such as shear-thinning, stress relaxation, the Fahraeus effect, the plasma-skimming, etc.. Using the framework of mixture theory an Eulerian-Eulerian two phase model is applied to model blood flow, where the plasma is treated as Newtonian fluid and the RBCs are treated as shear thinning fluid.[5]

Experimental Investigation of Flow-Induced Vibration in Gas/Shear-Thinning Liquid Flows in Vertical Pipe

2020 ◽  
Author(s):  
Ruinan Lin ◽  
Ke Wang ◽  
Qing Li ◽  
Narakorn Srinil ◽  
Fangjun Shi
Keyword(s):  
Newtonian Fluid ◽  
Industrial Process ◽  
Flow Region ◽  
Shear Thinning ◽  
Maximum Energy ◽  
Internal Diameter ◽  
Flow Induced Vibration ◽  
Two Phase ◽  
Liquid Flows ◽  
Shear Thinning Fluid

Abstract The non-Newtonian shear-thinning fluid widely exists in the industrial process and the rheology exerts a significant influence on the flow pattern transition and flow-induced vibration (FIV). However, studies on the rheology effect of the liquid phase in the vertical upward two-phase flows are quite lacking due to the complexity of non-Newtonian fluid properties. In the present study, the vertical upward gas/shear-thinning liquid flows experiments are conducted on a rigid acrylic pipe with an internal diameter of 20 mm. Three different Carboxymethyl Cellulose (CMC) solutions are used as the non-Newtonian fluid, aimed at capturing a two-phase flow regime transition including the vertical slug, churn and annular flows. The results indicate that the maximum energy spectral densities of vibration occur at the slug-to-churn flow transition boundary at low liquid velocities and the annular flow region under high liquid velocities, respectively. The effects of the rheology of the shear-thinning fluid in terms of the flow patterns and FIV are also presented and discussed.

scholarly journals Numerical simulation for the single-bubble electrospinning process

2015 ◽  
Vol 19 (4) ◽  
pp. 1255-1259 ◽  
Author(s):  
Lan Xu ◽  
Jiang-Hui Zhao ◽  
Hua Liu
Keyword(s):  
Stokes Equations ◽  
Turbulent Viscosity ◽  
Electrospinning Process ◽  
Single Bubble ◽  
Navier Stokes ◽  
Two Phase ◽  
Navier Stokes Equations ◽  
Two Fluids ◽  
Complex Phenomena ◽  
Volume Of Fluids

This paper studies numerically the two-phase flow in the single-bubble electrospinning process by solving the modified Navier-Stokes equations under the influence of electric field, and the interface between the two fluids has been determined by using the volume of fluids method. A realizable k-? model is used to model the turbulent viscosity. The numerical results offer in-depth insight into physical understanding of many complex phenomena which cannot be fully explained experimentally.

Rheological studies of functional polyurethane composite

2017 ◽  
Vol 50 (3) ◽  
pp. 222-240
Author(s):  
Sayavur I Bakhtiyarov ◽  
Jimmie C Oxley ◽  
James L Smith ◽  
Philipp M Baldovi
Keyword(s):  
Newtonian Fluid ◽  
Power Law ◽  
Effective Viscosity ◽  
Aluminum Content ◽  
Fluid Model ◽  
Shear Thinning ◽  
Testing Time ◽  
Two Phase ◽  
Bingham Plastic ◽  
Polyurethane Composite

The rheological dynamic characteristics of the functional Polyurethane composite as well as its compounds ( triethanolamine (TEOA) and toluene-2,4-diisocyanate (TDI)) with and without solid additives (aluminum flakes) were experimentally measured using a computer-controlled mechanical spectrometer (rheometer) ARES-G2. Rheological studies showed that both components behave as viscous Newtonian fluids. TEOA exhibits a strong temperature-thickening behavior. TEOA with aluminum flake additives behaves as a viscous Newtonian fluid. The effective viscosity of the two-phase mixture increases with the concentration of the aluminum additive and decreases with the temperature rise. The rheometric tests showed that the effective viscosity of the TDI/Al mixture increases with the aluminum content. The mixture exhibits thermal-thickening and shear-thinning behaviors with the yield stress. The system can be described with the Bingham plastic model. It is determined that TEOA/TDI composite exhibits a strong time-thickening and shear-thinning behaviors. The rheological behavior of this composite can be described with the power-law generalized non-Newtonian fluid model. The effective viscosity of TEOA/TDI/Al composite increases with both the testing time (exponentially) and the aluminum content (polynomial) in the mixture. However, these shear-thinning composites obey the power-law generalized non-Newtonian fluid model, and their flow curves can be described by the logarithmic law.

A Non-Newtonian Fluid Flow Model for the Slip Condition on Blood Flow through a Stenosed Artery using Power-law Fluid

2018 ◽  
Vol 9 (7) ◽  
pp. 871-879
Author(s):  
Rajesh Shrivastava ◽  
R. S. Chandel ◽  
Ajay Kumar ◽  
Keerty Shrivastava and Sanjeet Kumar
Keyword(s):  
Blood Flow ◽  
Fluid Flow ◽  
Newtonian Fluid ◽  
Power Law ◽  
Flow Model ◽  
Slip Condition ◽  
Power Law Fluid ◽  
Stenosed Artery ◽  
Flow Through

Numerical Modeling of Evolution of Boundary Between Incompressible Gas and Liquid in Two-Dimensional Region

2006 ◽  
Vol 4 ◽  
pp. 224-236
Author(s):  
A.S. Topolnikov
Keyword(s):  
Numerical Modeling ◽  
Interphase Boundary ◽  
Incompressible Liquid ◽  
Stokes Equations ◽  
Numerical Code ◽  
Navier Stokes ◽  
Two Phase ◽  
Navier Stokes Equations ◽  
Incompressible Media ◽  
Good Agreement

The paper is devoted to numerical modeling of Navier–Stokes equations for incompressible media in the case, when there exist gas and liquid inside the rectangular calculation region, which are separated by interphase boundary. The set of equations for incompressible liquid accounting for viscous, gravitational and surface (capillary) forces is solved by finite-difference scheme on the spaced grid, for description of interphase boundary the ideology of Level Set Method is used. By developed numerical code the set of hydrodynamic problems is solved, which describe the motion of two-phase incompressible media with interphase boundary. As a result of numerical simulation the solutions are obtained, which are in good agreement with existing analytical and experimental solutions.

scholarly journals Obtaining Expressions for Time-Dependent Functions That Describe the Unsteady Properties of Swirling Jets of Viscous Fluid

Mathematics ◽  
2021 ◽  
Vol 9 (16) ◽  
pp. 1860
Author(s):  
Eugene Talygin ◽  
Alexander Gorodkov
Keyword(s):  
Blood Flow ◽  
Viscous Fluid ◽  
Swirling Flow ◽  
Fluid Flows ◽  
Theoretical Method ◽  
Flow Channel ◽  
Navier Stokes ◽  
Swirling Jets ◽  
Continuity Equations ◽  
Dynamic Velocity

Previously, it has been shown that the dynamic geometric configuration of the flow channel of the left heart and aorta corresponds to the direction of the streamlines of swirling flow, which can be described using the exact solution of the Navier–Stokes and continuity equations for the class of centripetal swirling viscous fluid flows. In this paper, analytical expressions were obtained. They describe the functions C0t and Г0t, included in the solutions, for the velocity components of such a flow. These expressions make it possible to relate the values of these functions to dynamic changes in the geometry of the flow channel in which the swirling flow evolves. The obtained expressions allow the reconstruction of the dynamic velocity field of an unsteady potential swirling flow in a flow channel of arbitrary geometry. The proposed approach can be used as a theoretical method for correct numerical modeling of the blood flow in the heart chambers and large arteries, as well as for developing a mathematical model of blood circulation, considering the swirling structure of the blood flow.

scholarly journals Experimental and Numerical Study on Water Filling and Air Expelling Process in a Pipe with Multiple Air Valves under Water Slow Filling Condition

Water ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2511
Author(s):  
Jintao Liu ◽  
Di Xu ◽  
Shaohui Zhang ◽  
Meijian Bai
Keyword(s):  
Numerical Model ◽  
Stokes Equations ◽  
Numerical Study ◽  
Practical Method ◽  
Navier Stokes ◽  
Physical Processes ◽  
Two Phase ◽  
Saint Venant Equations ◽  
Water Filling ◽  
Air Valve

This paper investigates the physical processes involved in the water filling and air expelling process of a pipe with multiple air valves under water slow filling condition, and develops a fully coupledwater–air two-phase stratified numerical model for simulating the process. In this model, the Saint-Venant equations and the Vertical Average Navier–Stokes equations (VANS) are respectively applied to describe the water and air in pipe, and the air valve model is introduced into the VANS equations of air as the source term. The finite-volume method and implicit dual time-stepping method (IDTS) with two-order accuracy are simultaneously used to solve this numerical model to realize the full coupling between water and air movement. Then, the model is validated by using the experimental data of the pressure evolution in pipe and the air velocity evolution of air valves, which respectively characterize the water filling and air expelling process. The results show that the model performs well in capturing the physical processes, and a reasonable agreement is obtained between numerical and experimental results. This agreement demonstrates that the proposed model in this paper offers a practical method for simulating water filling and air expelling process in a pipe with multiple air valves under water slow filling condition.

Two-Phase Flow and Heat Transfer in Rectangular Micro-Channels

2003 ◽  
Author(s):  
Weilin Qu ◽  
Seok-Mann Yoon ◽  
Issam Mudawar
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Flow Pattern ◽  
Two Phase Flow ◽  
Flow Patterns ◽  
Heat Sinks ◽  
Phase Flow ◽  
Micro Channel ◽  
Two Phase ◽  
Micro Channels

Knowledge of flow pattern and flow pattern transitions is essential to the development of reliable predictive tools for pressure drop and heat transfer in two-phase micro-channel heat sinks. In the present study, experiments were conducted with adiabatic nitrogen-water two-phase flow in a rectangular micro-channel having a 0.406 × 2.032 mm cross-section. Superficial velocities of nitrogen and water ranged from 0.08 to 81.92 m/s and 0.04 to 10.24 m/s, respectively. Flow patterns were first identified using high-speed video imaging, and still photos were then taken for representative patterns. Results reveal that the dominant flow patterns are slug and annular, with bubbly flow occurring only occasionally; stratified and churn flow were never observed. A flow pattern map was constructed and compared with previous maps and predictions of flow pattern transition models. Annual flow is identified as the dominant flow pattern for conditions relevant to two-phase micro-channel heat sinks, and forms the basis for development of a theoretical model for both pressure drop and heat transfer in micro-channels. Features unique to two-phase micro-channel flow, such as laminar liquid and gas flows, smooth liquid-gas interface, and strong entrainment and deposition effects are incorporated into the model. The model shows good agreement with experimental data for water-cooled heat sinks.

Sign in / Sign up

Export Citation Format

Share Document