On the role of discrete mass conservation for non-Boussinesq flow simulations in enclosures

2017 ◽  
Vol 104 ◽  
pp. 1283-1299 ◽  
Author(s):  
Mukesh Kumar ◽  
Ganesh Natarajan
Keyword(s):  
Mass Conservation ◽  
Flow Simulations ◽  
Discrete Mass

scholarly journals Haemodynamic flow conditions at the initiation of high-shear platelet aggregation: a combined in vitro and cellular in silico study

2020 ◽  
Vol 11 (1) ◽  
pp. 20190126 ◽  
Author(s):  
B. J. M. van Rooij ◽  
G. Závodszky ◽  
A. G. Hoekstra ◽  
D. N. Ku
Keyword(s):  
Platelet Aggregation ◽  
In Silico ◽  
Platelet Rich Plasma ◽  
High Shear ◽  
Shear Rates ◽  
Flow Simulations ◽  
In Silico Study ◽  
Platelet Aggregates

The influence of the flow environment on platelet aggregation is not fully understood in high-shear thrombosis. The objective of this study is to investigate the role of a high shear rate in initial platelet aggregation. The haemodynamic conditions in a microfluidic device are studied using cell-based blood flow simulations. The results are compared with in vitro platelet aggregation experiments performed with porcine whole blood (WB) and platelet-rich-plasma (PRP). We studied whether the cell-depleted layer in combination with high shear and high platelet flux can account for the distribution of platelet aggregates. High platelet fluxes at the wall were found in silico . In WB, the platelet flux was about twice as high as in PRP. Additionally, initial platelet aggregation and occlusion were observed in vitro in the stenotic region. In PRP, the position of the occlusive thrombus was located more downstream than in WB. Furthermore, the shear rates and stresses in cell-based and continuum simulations were studied. We found that a continuum simulation is a good approximation for PRP. For WB, it cannot predict the correct values near the wall.

scholarly journals Why a Large-Scale Mode Can Be Essential for Understanding Intracellular Actin Waves

Cells ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 1533 ◽  
Author(s):  
Carsten Beta ◽  
Nir S. Gov ◽  
Arik Yochelis
Keyword(s):  
Large Scale ◽  
Mass Conservation ◽  
Coarse Grained ◽  
Cellular Functions ◽  
Multi Scale ◽  
Spatio Temporal ◽  
Actin Waves ◽  
Inhibitor Type ◽  
Activator Inhibitor Type

During the last decade, intracellular actin waves have attracted much attention due to their essential role in various cellular functions, ranging from motility to cytokinesis. Experimental methods have advanced significantly and can capture the dynamics of actin waves over a large range of spatio-temporal scales. However, the corresponding coarse-grained theory mostly avoids the full complexity of this multi-scale phenomenon. In this perspective, we focus on a minimal continuum model of activator–inhibitor type and highlight the qualitative role of mass conservation, which is typically overlooked. Specifically, our interest is to connect between the mathematical mechanisms of pattern formation in the presence of a large-scale mode, due to mass conservation, and distinct behaviors of actin waves.

The Segregated Approach to Predicting Viscous Compressible Fluid Flows

1987 ◽  
Vol 109 (2) ◽  
pp. 268-277 ◽  
Author(s):  
J. P. Van Doormaal ◽  
G. D. Raithby ◽  
B. H. McDonald
Keyword(s):  
Numerical Method ◽  
Compressible Fluid ◽  
Equations Of Motion ◽  
Fluid Flows ◽  
Mass Conservation ◽  
Viscous Compressible Fluid ◽  
Algebraic Equations ◽  
Simple Method ◽  
Compressible Fluid Flows

The SIMPLE method of Patankar and Spalding and its variants such as SIMPLER, SIMPLEC, and SIMPLEX are segregated methods for solving the discrete algebraic equations representing the equations of motion for an incompressible fluid flow. The present paper presents the extension of these methods to the solution of compressible fluid flows within the context of generalized segregated approach. To provide a framework for better understanding the segregated approach to solving viscous compressible fluid flows an interpretation of the role of pressure in the numerical method is presented. With this interpretation it becomes evident that the linearization of the equation for mass conservation and the approach used to solve the linearized algebraic equations representing the equations of motion are important in determining the performance of the numerical method. The relative performances of the various segregated methods are compared for several subsonic and supersonic compressible fluid flows.

scholarly journals Role of State-to-State Kinetics in Determining Transport Coefficients for Hypersonic Flow Simulations

2014 ◽  
Vol 7 (1) ◽  
pp. 173-180
Author(s):  
Eswar Josyula ◽  
Jonathan M. Burt ◽  
William F. Bailey ◽  
Prakash Vedula
Keyword(s):  
Hypersonic Flow ◽  
Transport Coefficients ◽  
Flow Simulations

scholarly journals Role of State-to-State Kinetics in Determining Transport Coefficients for Hypersonic Flow Simulations

2014 ◽  
Vol 7 (1) ◽  
pp. 173-180 ◽  
Author(s):  
Eswar Josyula ◽  
Jonathan M. Burt ◽  
William F. Bailey ◽  
Prakash Vedula
Keyword(s):  
Hypersonic Flow ◽  
Transport Coefficients ◽  
Flow Simulations

PHYSICAL AND MATHEMATICAL MODELING OF METAL-SLAG EXCHANGES IN GAS-STIRRED LADLES

MRS Advances ◽  
2017 ◽  
Vol 2 (61) ◽  
pp. 3821-3829
Author(s):  
Luis E. Jardón-Pérez ◽  
A. López-Gutierrez ◽  
Alfredo Vazquez ◽  
C. González-Rivera ◽  
M. A. Ramirez-Argaez
Keyword(s):  
Mathematical Model ◽  
Mass Conservation ◽  
Momentum Conservation ◽  
Conservation Equation ◽  
Steel Ladle ◽  
Metallic Inclusions ◽  
Flow Phenomena ◽  
Rigorous Study ◽  
Turbulent Momentum

AbstractLadle refining plays a key role in achieving the quality of the steel since in this reactor temperature and chemical composition is adjusted, elimination of non-metallic inclusions is performed, and also deoxidation and desulphurization are operations taking place in the refining process. Specifically, the metal-slag mass exchanges have not received much attention through scientific studies. In this work, a rigorous study on the mass exchange between metal and slag is presented through a scaled water physical model. In the model, thymol (playing the role of a solute such as sulfur) is added to the water (playing the role of steel) and silicon oil (playing the role of slag) picks up the thymol, while the ladle is agitated with the central injection of gas. The evolution of thymol concentration in time was measured. Also, a mathematical model was developed and cast into the commercial CFD code Fluent Ansys to represent the fluid flow phenomena and the mass transfer through the solution of the continuity equation, the turbulent momentum conservation equations and the species mass conservation equation. There is a good agreement between the measured and the computed results regarding the thymol concentration evolution in water and consequently the mathematical model was validated regarding the mass species metal-slag exchanges and it may be used to study metal-slag exchanges in the steel ladle such as deoxidation or desulphurization.

scholarly journals Dermal Denticles of Three Slowly Swimming Shark Species: Microscopy and Flow Visualization

Biomimetics ◽  
2019 ◽  
Vol 4 (2) ◽  
pp. 38 ◽  
Author(s):  
Katrine Feld ◽  
Anne Noer Kolborg ◽  
Camilla Marie Nyborg ◽  
Mirko Salewski ◽  
John Fleng Steffensen ◽  
...  
Keyword(s):  
Functional Role ◽  
Shark Species ◽  
Surface Drag ◽  
Greenland Shark ◽  
Shark Skin ◽  
Flow Simulations ◽  
Micro Piv ◽  
Image Velocimetry ◽  
Biomimetic Structures

Shark skin has for many years inspired engineers to produce biomimetic structures reducing surface drag or acting as an anti-fouling layer. Both effects are presumed to be consequences of the structure of shark skin that is composed of arrays of so-called dermal denticles. However, the understanding of the full functional role of the dermal denticles is still a topic of research. We report optical microscopy and scanning electron microscopy of dermal denticles from three slowly swimming shark species for which the functional role of the dermal denticles is suggested as one of defense (possibly understood as anti-fouling) and/or abrasion strength. The three species are Greenland shark (Somnosius microcephalus), small-spotted catshark (Scyliorhinus canicula) and spiny dogfish (Squalus acanthias). Samples were taken at over 30 different positions on the bodies of the sharks. In addition, we demonstrate that the flow pattern near natural shark skin can be measured by micro-PIV (particle image velocimetry). The microfluidic experiments are complemented by numerical flow simulations. Both visualize unsteady flow, small eddies, and recirculation bubbles behind the natural dermal denticles.

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