Bridging the Gap Between Continuum Mechanical Microrotation Viscosity and Lagrangian Point-Particles

2013 ◽  
Vol 135 (12) ◽  
Author(s):  
Helge I. Andersson ◽  
Lihao Zhao
Keyword(s):  
Fluid Dynamics ◽  
Simple Relation ◽  
Lagrangian Point ◽  
Flow Variable ◽  
Particle Loading ◽  
Carrier Fluid ◽  
Point Particles ◽  
Fluid Property ◽  
Dilute Suspension ◽  
Made In

The microrotation viscosity is an essential fluid property in micropolar fluid dynamics. By considering a dilute suspension of inertial spherical point-particles in an otherwise Newtonian fluid, an explicit analytical expression for the microrotation viscosity is derived. This non-Newtonian continuum mechanical fluid property is seen to be proportional with the viscosity of the carrier fluid and the local particle loading. A number of assumptions were made in order to arrive at this simple relation, which implies that the microrotation viscosity should be considered as a flow variable rather than as a constant fluid property.

Aggregation Studies: MR and MA With Poxvirus

1967 ◽  
Vol 25 ◽  
pp. 90-91
Author(s):  
D. G. Sharp ◽  
Kwang Soo Kim
Keyword(s):  
Cell Interaction ◽  
Actual State ◽  
New Host ◽  
Virus Particles ◽  
Particle Level ◽  
Dilute Suspension ◽  
The Individual ◽  
Quality Factor Q ◽  
Made In ◽  
Number Of Particles

The only instrument that gives direct information about virus-cell interaction at the individual particle level is the electron microscope. The counting of virus particles sedimented from dilute suspension for electron microscopy showed first that rather few of them produce plaques. Soon it was shown that the quality factor (Q=PFU/particles) was not a constant. It changed during the repeated passages required for adaptation of a virus to growth in a new host cell. More recently changes in Q have been observed when changes are made in the state of aggregation of the virus particles. These changes, their measurement and their meaning are the substance of this paper.Virus particles sedimented from dilute suspension fall upon a flat surface producing a pattern that shows coincidence pairs, triplets, etc., produced by chance falling together of separate particles. The number of these is small and it can be calculated. Aggregation in excess of this amount is true aggregation. It is the actual state of the virus particle population that encounters the cells of the monolayer on which plaques appear. From electron micrographs the frequency Ni of groups containing i particles is determined together with the total number of particles.

Numerical Reproduction of DDT in Small Scale Channels

2017 ◽  
Author(s):  
Ke Ren ◽  
Alexei Kotchourko ◽  
Alexander Lelyakin ◽  
Thomas Jordan
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Efficient Method ◽  
Combustion Model ◽  
Small Scale ◽  
Experimental Facility ◽  
Deflagration To Detonation Transition ◽  
Detonation Transition ◽  
Made In

Deflagration to detonation transition (DDT) is a quite challenging subject in computational fluid dynamics both from a standpoint of the phenomenon nature understanding and from extremely demanding computational efforts. In the article the hybrid DDT combustion model is introduced as an efficient method to simulate the DDT problems. As verification, two DDT experiments made in experimental facility MINI RUT are used.

scholarly journals Thermodynamics of Acoustic Black Holes in Two Dimensions

2016 ◽  
Vol 2016 ◽  
pp. 1-8
Author(s):  
Baocheng Zhang
Keyword(s):  
Fluid Dynamics ◽  
Black Holes ◽  
Black Hole ◽  
Two Dimensions ◽  
Two Dimensional ◽  
Schwarzschild Black Hole ◽  
First Law Of Thermodynamics ◽  
Entropic Gravity ◽  
Acoustic Black Holes ◽  
Made In

It is well-known that the thermal Hawking-like radiation can be emitted from the acoustic horizon, but the thermodynamic-like understanding for acoustic black holes was rarely made. In this paper, we will show that the kinematic connection can lead to the dynamic connection at the horizon between the fluid and gravitational models in two dimensions, which implies that there exists the thermodynamic-like description for acoustic black holes. Then, we discuss the first law of thermodynamics for the acoustic black hole via an intriguing connection between the gravitational-like dynamics of the acoustic horizon and thermodynamics. We obtain a universal form for the entropy of acoustic black holes, which has an interpretation similar to the entropic gravity. We also discuss the specific heat and find that the derivative of the velocity of background fluid can be regarded as a novel acoustic analogue of the two-dimensional dilaton potential, which interprets why the two-dimensional fluid dynamics can be connected to the gravitational dynamics but it is difficult for four-dimensional case. In particular, when a constraint is added for the fluid, the analogue of a Schwarzschild black hole can be realized.

scholarly journals Impact of Electrification and Particle Loading on Velocity Profile of Dusty Fluid Flow Over a Stretching Sheet

2020 ◽  
Vol 9 (3) ◽  
pp. 3140-3143
Keyword(s):  
Fluid Flow ◽  
Velocity Profile ◽  
Phase Velocity ◽  
Particle Density ◽  
Vertical Direction ◽  
Fluid Phase ◽  
Particle Phase ◽  
Particle Loading ◽  
Carrier Fluid ◽  
Dusty Fluid

The performance of incompressible, laminar, boundary- layer flows over a semi-infinite horizontal stretchable plate is considered. The dusty fluid flow problems are modelled and solved in agreement with two-way coupling model. The particle phase momentum equation in the vertical direction is considered where as that for fluid phase is neglected. Here the electrification term added in not from the supply from outside rather it is the generation due to collision of particles So the effects of particle loading and electrification on velocity profile have been studied. From the result analysis it is concluded that electrification and particle density have significant effect on particle phase velocity, whereas carrier fluid phase has negligible effect. The particle phase velocity increases with increasing of electrification parameter and decreases with increase of loading ratio.

Adapting Parametric Acoustic Arrays for Tomographic Imaging

1988 ◽  
Vol 10 (3) ◽  
pp. 196-203
Author(s):  
Anni Cai ◽  
Jing Ao Sun ◽  
Glen Wade
Keyword(s):  
Theoretical Model ◽  
Cross Section ◽  
Tomographic Reconstruction ◽  
Simple Relation ◽  
Tomographic Imaging ◽  
Nonlinear Parameter ◽  
Acoustic Arrays ◽  
Parametric Array ◽  
The Cross ◽  
Made In

In this paper, we present a theoretical model of a parametric array for tomographic applications. The array in the model is assumed to extend right up to the receiver and its cross section is assumed not to be negligible. These two assumptions have not been previously made in applications concerned with tomography. We invoke conditions that permit the derivation of a simple relation for tomographic reconstruction of variations in the acoustic nonlinear parameter throughout the cross section of an object.

Constitutive equations in suspension mechanics. Part 2. Approximate forms for a suspension of rigid particles affected by Brownian rotations

1976 ◽  
Vol 76 (1) ◽  
pp. 187-208 ◽  
Author(s):  
E. J. Hinch ◽  
L. G. Leal
Keyword(s):  
Constitutive Equations ◽  
Fluid Model ◽  
Second Order ◽  
Order Tensor ◽  
Rigid Particles ◽  
Dilute Suspension ◽  
Suspension Mechanics ◽  
Made In

Approximate constitutive equations are derived for a dilute suspension of rigid spheroidal particles with Brownian rotations, and the behaviour of the approximations is explored in various flows. Following the suggestion made in the general formulation in part 1, the approximations take the form of Hand's (1962) fluid model, in which the anisotropic microstructure is described by a single second-order tensor. Limiting forms of the exact constitutive equations are derived for weak flows and for a class of strong flows. In both limits the microstructure is shown to be entirely described by a second-order tensor. The proposed approximations are simple interpolations between the limiting forms of the exact equations. Predictions from the exact and approximate constitutive equations are compared for a variety of flows, including some which are not in the class of strong flows analysed.

Basic Fundamentals of Extrusion and Mixing Theory

1972 ◽  
Vol 45 (5) ◽  
pp. 1421-1433 ◽  
Author(s):  
J. J. Boguslawski
Keyword(s):  
Fluid Dynamics ◽  
Process Control ◽  
Empirical Data ◽  
Practical Experience ◽  
Polymer Processing ◽  
Fundamental Theory ◽  
Rubber Particles ◽  
Extrusion Technology ◽  
Mathematical Relationships ◽  
Made In

Abstract The first mechanically driven extruders for rubber and rubber-like materials were developed by Francis Shaw in 1879 in England and John Royle in 1880 in the U. S. A. For nearly 60 years the design of extruder screws remained as an art. With rapidly expanding plastic markets and rapidly rising labor and processing machinery costs, the extruder users and builders realized that only close co-ordination and cooperation among scientists, engineers, and process workers could develop an extruder which would be the most universal and economical tool in polymer processing. Between 1946 and 1953 most of the modern extrusion theory was developed. It has been proven that extrusion theory, when combined with test data and practical experience, is an extremely useful tool. Due to an abundance of empirical data and fundamental theory, extrusion technology has now grown far beyond the level of a mechanical art. At least part of the process can be described by mathematical relationships through the application of rheology, thermodynamics, and fluid dynamics theory. Important advances have been made in process control as well as in increasing output. It is significant that the technology of the rubber extruder, the parent of the plastic extruder, can even now benefit directly from these developments. The transition from hot feeding to use of cold rubber particles can be mentioned as an example.

scholarly journals THEORETICAL FORMS OF SHORELINES

2011 ◽  
Vol 1 (7) ◽  
pp. 11
Author(s):  
W. Grijm
Keyword(s):  
Simple Relation ◽  
Mathematical Treatment ◽  
Physical Processes ◽  
Wave Characteristics ◽  
Wave Approach ◽  
Real Value ◽  
Detailed Picture ◽  
Made In

In previous publications Pelnard-Considere, Bruun and larras have d.erived theoretical shore formations. When doing so, it is necessary to idealize the conditions, such as a lxttoral transport by waves only, unvarying wave characteristics and a simple relation between the angle of wave approach and the littoral transport. Moreover various other simplifications have to be made in order to make it possible to handle the equations. The question may arise whether results, obtained from such an idealized situation, have any value for practical cases, where the conditions are much more complex and variable. The answer is no when we expect to obtain a true and detailed picture of the development of any particular stretch of coast. Such theoretical exercises can be of real value, however, because they help us to understand why and how certain formations come into being and how they are influenced by certain physical processes* This is the case for instance with such formations as deltas, spits and tombolos. We cannot say that we really know the function which determines the littoral transport. Up to now one of the simplifications in the mathematical treatment has been the restriction to stay within an area in which the values of

scholarly journals Fire Propagation Study in Naturally Ventilated Buildings using Computer Simulation

2019 ◽  
Author(s):  
Raja Singh
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Natural Ventilation ◽  
The Other ◽  
Dynamics Simulation ◽  
Small Cells ◽  
Base Case ◽  
Fire Propagation ◽  
Naturally Ventilated Buildings ◽  
Made In

Fire safety is of imminent concern in buildings since the first building was made. In a fire, the major concerns are evacuation and safety from the smoke and the heat. Smoke and the heat of the fire spreads in the building from one space to the other if there is continuity in space. Naturally ventilated buildings are made with a premise of enhancing this vertical and horizontal continuity in order to create health ventilation and air movement. In case of a fire, these natural ventilation pathways can facilitate the flow of smoke and heat through the spaces. This study aims at verifying using computational fluid dynamics simulation the actual role played by natural ventilation elements in the propagation of fire in buildings. A CFD (Computational Fluid Dynamics) package called FDS(Fire Dynamics Simulator) has been used preceded by a 3D model made in a 3D modelling software. The CFD software uses laws of conservation of mass, momentum and energy to actually evaluate the change in the mass, momentum and energy in small cells. These cells are of which the test space is made up of and is divided into. A test case is made up of a building with conventional design. This is tested against enhanced naturally ventilated buildings with parametric iterations. The first model of the building has one feature and then the feature gets added and tested again in each case. Here, we can compare in real time the effect of each feature against a base case and against the other features provided for enhanced natural ventilation. What is compared in all the results is the slices made at the same location. This gives us an insight on the fire propagation in naturally ventilated buildings and designers can use this to prevent fires from endangering the lives of the inhabitants.

LBE in the Framework of Computational-Fluid Dynamics

2018 ◽  
Author(s):  
Sauro Succi
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Numerical Scheme ◽  
General Framework ◽  
The Past ◽  
Computational Fluid Dynamics Cfd ◽  
Made In

This chapter outlines the main properties of LB as a numerical scheme within the general framework of computational fluid dynamics (CFD). The matter has witnessed significant developments in the past decade, and even though the bottomline picture of LB as a very effective numerical scheme stands intact, a number of assessments made in the previous book need some revision. Since the matter is fairly technical, only general notions shall be discussed, leaving in-depth details to the original literature.

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