Dynamic Deformation Analysis of a Red Blood Cell in Steady and Unsteady Shear Flows

2008 ◽  
Author(s):  
Sadao Bessho ◽  
Masanori Nakamura ◽  
Kenichirou Koshiyama ◽  
Shigeo Wada
Keyword(s):  
Velocity Field ◽  
Blood Cells ◽  
Predictive Accuracy ◽  
Dynamic Deformation ◽  
Artificial Organs ◽  
Deformation Analysis ◽  
Flow Conditions ◽  
Flow Velocity Field ◽  
Dynamical Deformation ◽  
Simple Flow

Quantitative evaluation of hemolysis, the breaking open of red blood cells (RBCs), is essential in designing artificial organs. Recently, numerical methods to quantify hemolysis from a measured or calculated macroscopic flow velocity field have been proposed [1]. Nevertheless, their predictive accuracy has not reached a satisfactory level required in practice. This would be because the conventional methods are mostly established based on the hemolysis tests under simple flow conditions and have not well considered deformation of RBCs. For further amelioration of the predictive accuracy, it would be necessary to take into account motion and dynamical deformation of individual RBCs in a flow field.

Radial Flow Velocity Field for Predicting Upper-Bound Solutions for Plane Strain Extrusion

1968 ◽  
Vol 90 (1) ◽  
pp. 45-50
Author(s):  
R. G. Fenton
Keyword(s):  
Velocity Field ◽  
Flow Field ◽  
Flow Velocity ◽  
Plane Strain ◽  
Upper Bound ◽  
Radial Flow ◽  
Flow Velocity Field ◽  
Wide Range ◽  
Ram Pressure ◽  
Considerable Range

The upper bound of the average ram pressure, based on an assumed radial flow velocity field, is derived for plane strain extrusion. Ram pressures are calculated for a complete range of reduction ratios and die angles, considering a wide range of frictional conditions. Results are compared with upper-bound ram pressures obtained by considering velocity fields other than the radial flow field, and it is shown that for a considerable range of reduction ratios and die angles, the radial flow field yields better upper bounds for the average ram pressure.

scholarly journals Using Long Term Simulations to Understand Heat Transfer Processes during Steady Flow Conditions in Combined Sewers

Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 570
Author(s):  
Mohamad Abdel-Aal ◽  
Simon Tait ◽  
Mostafa Mohamed ◽  
Alma Schellart
Keyword(s):  
Heat Transfer ◽  
Heat Recovery ◽  
Predictive Accuracy ◽  
Flow Conditions ◽  
Empirical Relationships ◽  
Taylor Diagram ◽  
Physical Phenomena ◽  
The Heat Transfer Coefficient ◽  
Empirical Approaches

This paper describes a new heat transfer parameterisation between wastewater and in-sewer air based on understanding the physical phenomena observed in free surface wastewater and in-sewer air. Long-term wastewater and in-sewer air temperature data were collected and studied to indicate the importance of considering the heat exchange with in-sewer air and the relevant seasonal changes. The new parameterisation was based on the physical flow condition variations. Accurate modelling of wastewater temperature in linked combined sewers is needed to assess the feasibility of in-sewer heat recovery. Historically, the heat transfer coefficient between wastewater and in-sewer air has been estimated using simple empirical relationships. The newly developed parameterisation was implemented and validated using independent long-term flow and temperature datasets. Predictive accuracy of wastewater temperatures was investigated using a Taylor diagram, where absolute errors and correlations between modelled and observed values were plotted for different site sizes and seasons. The newly developed coefficient improved wastewater temperature modelling accuracy, compared with the older empirical approaches, which resulted in predicting more potential for heat recovery from large sewer networks. For individual locations, the RMSE between observed and predicted temperatures ranged between 0.15 and 0.5 °C with an overall average of 0.27 °C. Previous studies showed higher RMSE ranges, e.g., between 0.12 and 7.8 °C, with overall averages of 0.35, 0.42 and 2 °C. The new coefficient has also provided stable values at various seasons and minimised the number of required model inputs.

Fluid Flow Field in the Annulus of Boiling Water (BWR) Nuclear Reactors Under Normal and Accident Conditions

2009 ◽  
Author(s):  
Raju Ananth ◽  
Karen Fujikawa ◽  
Jay Gillis
Keyword(s):  
Fluid Flow ◽  
Velocity Field ◽  
Flow Field ◽  
Pressure Vessel ◽  
Theoretical Study ◽  
Nuclear Reactors ◽  
Boiling Water ◽  
Flow Conditions ◽  
Accident Conditions ◽  
Reactor Pressure

This paper presents a theoretical study of the velocity field in the annulus formed between the Reactor Pressure Vessel (RPV) and the shroud of a Boiling Water Reactor (BWR) under normal and accident flow conditions. Simplified geometry and an ideal irrotational flow are assumed to solve the problem using velocity potentials.

Simulation Research on Stress – Damage Law of the Blood Cells

2012 ◽  
Vol 482-484 ◽  
pp. 776-779
Author(s):  
Xiong Xie ◽  
Jian Ping Tan
Keyword(s):  
Blood Cell ◽  
External Force ◽  
Blood Cells ◽  
Simulation Analysis ◽  
Artificial Organs ◽  
Simulation Research ◽  
Axial Diameter ◽  
Concave Shape ◽  
Damage Law ◽  
Stress Damage

Through simulation analysis of the blood cell by Abques under the function of the different pressures, the change of the cell’s axial diameter and the importance of the effect of external force and double concave shape on the erythrocyte’s deformability are obtained. It lays the foundation for the research artificial organs lubrication.

scholarly journals Electrohydrodynamics of stationary cone-jet streaming

2015 ◽  
Vol 471 (2182) ◽  
pp. 20150290 ◽  
Author(s):  
Andrey V. Subbotin ◽  
Alexander N. Semenov
Keyword(s):  
Velocity Field ◽  
Electric Field ◽  
Flow Velocity ◽  
Entropy Production ◽  
Cone Angle ◽  
Surface Current ◽  
Conductive Liquid ◽  
Flow Velocity Field ◽  
Principle Of Maximum Entropy ◽  
Principle Of Maximum

We discover novel types of stationary cone-jet steams emitting from a nozzle of a syringe loaded with a conductive liquid. The predicted cone-jet-flow geometries are based on the analysis of the electrohydrodynamic equations including the surface current. The electric field and the flow velocity field inside the cone are calculated. It is shown that the electric current along the conical stream depends on the cone angle. The stable values of this angle are obtained based on the Onsager’s principle of maximum entropy production. The characteristics of the jet that emits from the conical tip are also studied. The obtained results are relevant both for the electrospraying and electrospinning processes.

Application of Taylor Vortices in Hemocompatibility Investigations

2003 ◽  
Vol 26 (4) ◽  
pp. 331-338 ◽  
Author(s):  
S. Körfer ◽  
S. Klaus ◽  
K. Mottaghy
Keyword(s):  
Laminar Flow ◽  
Protein Adsorption ◽  
Secondary Flows ◽  
Artificial Organs ◽  
Vortical Flow ◽  
Taylor Vortex ◽  
Vortex Center ◽  
Flow Conditions ◽  
Shear Rates ◽  
Taylor Vortices

Background Artificial organs, implants and extracorporeal circulation affect the physiological flow characteristics of blood as a liquid organ. These artificial systems consist of a wide variety of biomaterials with different geometries and, therefore, with their own flow properties. Secondary flow also occurs in extra – as well as in intracorporeal circulation. Methods In order to investigate the influence of vortical flow conditions a modified Taylor-Couette system was introduced. It consisted of two coaxial cylinders whose surfaces were the target of investigation. The annular gap was filled with donor blood shear and secondary flows were produced by rotating the inner cylinder. Platelet activation and protein adsorption were investigated as markers for thrombogenicity. Results At shear rates high enough to establish stable Taylor vortices (G ≥ 550 s −1) significant differences between vortical Taylor flow and steady laminar flow were detected. At shear rates of G ≥ 550 s −1 laminar flow caused a significantly higher platelet drop and PF4 release when compared to Taylor vortex flow. Also protein adsorption per square unit was significantly higher for laminar flow. Conclusions Based on the present data we conclude that vortical flow patterns lead to an accumulation of platelets and plasma proteins in the vortex center and therefore to a decreased probability of contact between platelets and material surfaces. It can be concluded that a preactivation of the platelets circulating in extracorporeal circuits can be manifested downstream in other geometrical configurations and flow conditions.

Study on Flow Velocity Field of Local Scour around the Pier Protected by the Sediment Storage Dam

2012 ◽  
Vol 594-597 ◽  
pp. 1975-1978
Author(s):  
Hai Jing Zhao ◽  
Dan Xun Li ◽  
Xing Kui Wang
Keyword(s):  
Velocity Field ◽  
Flow Velocity ◽  
Physical Model ◽  
Model Test ◽  
Three Dimensional ◽  
Local Scour ◽  
Physical Model Test ◽  
Three Dimensional Flow ◽  
Sediment Storage ◽  
Flow Velocity Field

Aimed at the representative project which is protected by the downstream sediment storage dam, three dimensional flow velocity field in local scour area around the separate bridge pier via physical model test was studied. The influences of shaping the eroded pit caused by the velocities in different directions were analyzed. The distribution results of flow velocity field in local scour pit near the pier protected by the sediment storage dam, deduced from the paper, will provide references for the defensive design of bridge projects.

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