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In this third paper, the fundamental mechanism of individual-machine transient stability is explained through Newtonian mechanics. The original Newtonian system with variant gravity is developed. This system is formed by a ball and the Earth. It is found that the Newtonian energy conversion strictly holds inside the system, and the equal area criterion can be considered a reflection of the Newtonian work. Based on these features, the stability characterizations of the system are given. Then, the original Newtonian system is extended to a generalized Newtonian system with multiple balls. It is found that this generalized Newtonian system can be decomposed into each two-ball-based subsystem, and the Newtonian energy conversion inside each subsystem is unique and different. This decomposition also ensures the independent parallel stability characterization of the generalized system. Finally, the strict mappings between Newtonian system stability and individual-machine transient stability are systematically analyzed. All these strict mappings fully reveal that the theoretical foundation of the individual-machine transient stability should be Newtonian mechanics.

This paper presents the control modelling and synthesis using a coupled multivariable under-actuated nonlinear adaptive U-model approach for an unmanned marine robotic platform. A nonlinear marine robotics model based on the dynamic equation using the Newtonian method and derivation with respect to the kinematics equations and rigid-body mass matrixes are explained. This nonlinear marine robotics model represents the underwater thruster dynamics, marine robotics dynamics and kinematics related to the earth-fixed frame. Coupled multivariable nonlinear adaptive control synthesis using a U-model approach for the Remotely Operated Vehicle (ROV) and Unmanned Surface Vessel (USV) represent an unmanned marine robotics application. A comparison is presented for the proposed nonlinear control approach between the U-model control approach with nonlinear Fuzzy Logic Control and Sliding Mode Control for the ROV and USV platforms. The results show minimum mean square error values and tracking performance between the plant or system model with the proposed method. Lastly, robustness and stability analysis for the proposed U-Model nonlinear control approach are presented by implementing an adaptive learning rate value.

The study of robotic micromanipulation is important for biomedical applications with live cells. Hydrodynamic trapping is arguably more favorable owing to the apparent lack of temperature gradients and tactile interaction. However, it offers challenges of modeling due to the complex nature of the physics governing the mechanics of trapping. This study aims to present a fully deterministic Multiphysics modeling of the hydrodynamic micro tweezers that actuated by external magnetic fields in a virtually infinite Newtonian fluid. Equation of motion is written to include all hydrodynamic interaction between the particles along with contact force. Early results dictate that it is possible to observe stable orbit for different cases although the interactions could rely on different physical phenomena in part.

Fluids in computational hydrodynamics are often considered Newtonian, meaning a constant viscosity, but that is just a crude approximation for many real-world examples. Accounting for Non-Newtonian behaviour can provide a significant improvement in simulation accuracy. We present a meshless solution for the natural convection of a power-law non-Newtonian fluid driven by differentially heated cavity walls. The Navier-Stokes and heat transport equations are coupled using the Boussinesq approximation and numerically solved with the generalized finite differences, explicit Euler stepping and Chorin's projection method.

In this work we present a general analysis of the extraordinary properties of surface Love waves and the unexpected wave phenomena that can occur in the Love wave waveguides. A brief history of the Love waves and their applications to Love wave sensors is given. The results of the author's recent research on Love wave sensors are presented. The analytical formula for the mass sensitivity of the Love wave sensor is shown. Extraordinary properties that reveal Love waves propagating in lossy media are introduced. Counterintuitive phenomena in Love wave waveguides such as: a) minimum of phase velocity as a function of liquid viscosity and b) maximum of attenuation as a function of liquid viscosity are reported. Moreover, the application of new mathematical tools in the analysis of Love wave sensors such as: Inverse Methods is discussed. New possible directions for research on Love wave sensors have been indicated.

Background and objectives: In order to achieve the mixing of blood and water simulation and consider that blood is a non-Newtonian fluid and water is a Newtonian fluid, we propose a new simulation model which is based on SPH. The problem that non-Newtonian fluid and Newtonian fluid can not mix well is solved.Methods: The model algorithm is divided into three steps in the realization process. Firstly, calculate the velocity of the mixed fluid components, then, calculate the impact factor for each particle in the mixed fluid and adjust for abnormal impact factors. Finally, calculate the acceleration of the mixed fluid particle and update the particle state (e.g., position). The second step is the key process, because the update and correction of the impact factors directly affect the stability of the system. At the same time, considering that the system has good parallel ability, we optimize it here.Results: We also take into account the fluency of the system while achieving the mixing of blood and water and the experimental results show that this fluid mixing model can not only achieve good miscibility of blood and water, but also smooth operation of the system.Conclusions: The experimental results show that the model can simulate the miscibility of blood and water, at the same time, as long as the fluid property parameters are set reasonably, the model can also simulate the miscibility between other non-Newtonian fluids and Newtonian fluids. What’s more, by adjusting the influence factor, the model can simulate the mixed fluid simulation.

This study is concerned with the two-phase flow in a microchannel. The liquids are Newtonian (de-ionized water and sunflower oil) and a Y-shaped microchannel is used. For this microfluidic device, numerical and experimental studies were conducted. The focus of this study is on the evolution of the interface and what happens at it, in terms of stresses, forces and other parameters. By validating the numerical simulations with experiments, it will allow us to go further to the diffusion process and non-Newtonian fluids.

In this study, we develop a semi-empirical approach to model the viscosity of Newtonian nanofluids. For nanofluid viscosity predicting in a wide range of temperature and mass fractions of the nanoparticles, the limited experimental data on base fluid and nanofluid of one mass fraction of nanoparticles are required (viscosity at one temperature and density at two or more temperatures). The verification of the proposed approach using experimental data on two types of nanofluids with metal oxide nanoparticles has been performed.

The small intestine is the primary site of enzymatic digestion and nutrient absorption in humans. Intestinal contractions facilitate digesta mixing, transport and contact with the absorptive surfaces. These motility patterns are regulated by an underlying electrical activity, termed slow waves. In this study, we use computational fluid dynamics simulation of flow and mixing of intestinal contents in the human duodenum with anatomically realistic geometry and contraction patterns. Parameters including the amplitude of contraction (10-50% reduction of radius) and the rheology of the digesta (Newtonian vs Non-Newtonian power law fluid) were altered in-order to study their effects on mixing. Interesting flow features such as stagnation points and reversed flow were observed with digesta. Increases in the amplitude of contraction lead to increased propulsion of digesta along the intestine and increased mixing.

Atherosclerosis is a common cardiovascular disease characterized by the accumulation of plaques on the artery walls, resulting in the lumen stenosis. Over the past few decades, this pathological condition has been deeply studied and computational fluid dynamics has played an important role in investigating the blood flow behavior. Commonly, the blood flow is assumed to be laminar and a Newtonian fluid. However, under a stenotic condition, the blood behaves as a non-Newtonian fluid and the pulsatile blood flow through coronary arteries could result in a transition from laminar to turbulent flow condition. The aim of the present study is to analyze and compare numerically by means of CFD the blood flow behavior, applying the k-ω SST model and a laminar assumption. The effects of Newtonian and non-Newtonian (Carreau) models were also studied. According to the results, the turbulent model is shown to give a better overall representation of pulsatile flow in stenotic arteries. In addition, the effect of non-Newtonian modeling was found to be more significant in wall shear stress measurements than in velocity profiles.

CFD analysis of blood flow within the carotid artery has been carried out due to the rise of strokes and carotid artery diseases. The carotid artery is bifurcated into internal and external ones. Most of the earlier work has been done considering blood as a single phase. However, in this work, blood is treated as multiphase (plasma and morphotic particles). Finite difference method has been used to perform the numerical analysis, using a second-order time discretization scheme. Mixture model theory of Euler-Euler approach is preferred over the Eulerian model. Human blood shows Newtonian and non-Newtonian characteristics. During the cardiac cycle, it behaves non-Newtonian with a shear rate ranging from 0.1 to100 s-1, while Newtonian; exhibiting a shear rate more than 100 s-1. For the present analysis, it is mathematically modelled as an incompressible, time-dependent Newtonian fluid with average values of density and viscosity for each phase. A real geometry of the carotid artery was created using Computed Tomography Angiography image of a carotid artery and its bifurcation. Navier-Stokes equation has been solved computationally, with multiphase boundary conditions in ANSYS 19. CFD is a potent tool in analyzing blood flow within the treated artery. Especially after Carotid End-Arterectomy (CEA) and Carotid Angioplasty with Stenting (CAS) has been carried out. Moreover, an optimized stent design can be carried out using this work after analyzing the flow characteristics and in coordination with CT angiography results. Stent flow regimes and stent meshing can be studied to design a particular stent for a particular case.

The paper investigates the drop formation process in the case of nozzles having non-circular cross-sections. The drops are created in a viscous Newtonian immiscible outer liquid, the injected fluids being either Newtonian or viscoelastic. We investigate the influence of nozzle geometry on the frequency of drop generation. We find no alteration of the frequency of drop generation when cross-sections have the same hydraulic diameter and when Newtonian fluids are injected. We also propose a simple model of the advance velocity of the apex of the drop based on experimental observations regarding the final stages of drop formation.

Computational fluid dynamics becomes an influential tool which gains insight into the physical performance of the circulatory system. Cardiovascular disease received less attention from a computational viewpoint; the present work analyses the blood flow in common carotid artery in head down tilt position. The common carotid artery has complex geometry and material properties, for this, 3-D computational models can improve our capability of understanding the mechanisms of disease progression. 3-D geometry of the common carotid artery is created in Creo, and Ansys CFX analyzes blood flow performance. Mainly, laminar flow is investigated for 10 timesteps, Blood is modeled as Non- Newtonian fluid, and the viscous laminar epsilon model is used during analysis. The simulations produce blood pressure effect on the walls of the human artery and velocity variation in inlet and outlet region with microgravity, and this methodology can be used to explore blood flow behavior in the blood vessel and to relate these to critical clinical issues.

Here we present a novel microrheometer able to provide reliable measurements of extremely low volume fluids. We demonstrate the transition from Newtonian to non-Newtonian behavior in a DNA hydrogel whose structure is strongly temperature dependent.

Cardiovascular disease leading to a heart attack is caused by coronary artery stenosis or obstruction. The change in shear wall stress around the coronary arteries is an important factor in the development of cardiovascular disease. In this work, we analyze the steady and transient behavior of left and right coronary artery blood flow. Then Newtonian and non-Newtonian models have been used to analyze wall shear stress of blood viscosity. Human blood being a non-Newtonian fluid exhibits shear thinning. During the cardiac cycle, it appears as a non-Newtonian fluid with a shear rate between 0.1~100 1/s, while Newtonian fluid exhibiting a shear rate greater than 100 1/s. During the steady-state analysis, the shear stress patterns on the walls in all models were uniform. However, the magnitude of the shear stress of the wall is affected by the model being used. When analyzing transients, blood flow stops and suddenly increases. Therefore, a model using the Generalized Power Law is suitable. Non-Newtonian factors were also analyzed to quantify the non-Newtonian behavior of human blood flow. The Newtonian blood viscosity model is a good approximation of moderately high shear regions; a Generalized Power Law model is recommended to obtain good approximation of low wall shear stress. Fluid Solid Interaction (FSI) analysis of CT scans of left coronary artery was carried out. To study the correlation between the induced flow rates, the tension of the cutting wall and the geometry of the artery; unstable FSI analysis was performed using commercial finite element software to evaluate and measure wall and shear stresses in the system. The left coronary artery is used as a boundary condition and a physiological pressure waveform has been applied. A comparison of results calculated for the FSI model and the solid wall model indicates that the distribution of wall shear stress is significantly affected by the consistency of the walls of arteries.

In this study, a static mode suspended microcantilever model was simulated employing the Finite Elements Method (FEM), to examine the deflection of the microcantilever's beam using Newtonian and Non-Newtonian fluids. The scope of this work is to design and simulate a suspended microcantilever biosensor for the determination of the fluids' dynamic viscosity and the relationship between the blood's hematocrit and the biosensor's sensitivity. These biosensors are microstructures which consist of a microfluidic channel embedded in a microcantilever biosensor. Fluid Structure Interaction (FSI) simulations performed to study the deflection of the microcantilever when Newtonian and Non-Newtonian fluids with different dynamic viscosity are used. For the dynamic viscosity determination of the Non-Newtonian fluids, the Brid-Carreau model was used. The results indicate a proportional relation between the beam's deflection and the fluids' dynamic viscosity.

The wave-particle dualism is one of the most important paradigms of modern physics, often attributing a particle character to objects that are in principle waves. One such example is a soliton, representing a wave that can propagate over extended distances without changing its shape, resembling the trajectories of rigid mechanical bodies in Newtonian physics, even in a collision process [1]. However, this analogy has strong restrictions as still wave properties are required and more importantly only the trivial solution of the momentum conservation equation (exactly equal solitions) can be addressed. Here we take the analogy one decisive step further, discussing completely Newtonian soliton collisions, detached from the wave description. Moreover, we show that the solitons act like extended massive objects, which deform in accord with the continuum mechanical concept of classical theory of elasticity. The interaction offers a variety of possibilities for controlled exchange of energy and momentum, opening a perspective for new applications of solitons in optical switching or trapping.

Ultrasonic is an important method to study the viscoelastic properties of liquid at high frequency. Relationship between the viscosity and phase change between incident wave and reflected wave from solidfluid interface was obtained by acoustic shear impedance model. High resolution time measurement is the key to determine the phase changes of Newtonian fluid which has decoupled relation between amplitude and phase of the reflection coefficient. Various parameters affecting phase difference including the material properties of the solid, the operating frequency and the resolution were discussed in this paper, then the time scales were analyzed theoretically for Newtonian fluid/Plexiglas combination. The results shown that time error of a few tenths of nanosecond can make large deviation in viscosity for lower viscosity products.

The paper is dedicated to the numerical modeling of materials, such as complex fluids, which exhibit intrinsic material instability in viscometric flows. Some notorious examples of complex fluids are polymer solutions, colloids, solid dispersions in liquids and soft solids (pastes, creams, greases). Most of these materials disclose structure instability beyond critical deformations and stresses, being characterized by the existence of a non-monotonic steady flow curve and the shear banding formation. Numerical simulations performed with a generalized Newtonian model confirm the existence of the shear banding in the gap of the rheometers, as a consequence of the coexisting asymptotic steady shear rates of the velocity distribution under constant shear stress. The present findings are consistent with the previous results published in literature and confirmed by experiments performed in our laboratory.

The paper is dedicated to the experimental study of the motion of magnetized spheres in tubes filled with pure viscous and viscoelastic fluids. The main goal of the study is to investigate the spheres motion with variable velocities in confined geometries. Due to the influence of the attractive magnetic force the spheres are accelerated, therefore a non-stationary fluid flow is generated in the tubes. The experiments put in evidence the fluctuation frequency and the rotational speed of the sphere during its displacement within the tube. The influence of the fluids rheology on the spheres motion is also determined.

The present study has been produced to analyze the steady state, laminar and Newtonian fluid flow via the rectangular channel with three equal spaced inclined perforated plates with screen boundary conditions settled at angles from $ - \frac{\pi }{4}$ to $\frac{\pi }{4}$ with κ = 2.2 and η = 0.78. The leading two-dimensional incompossible Navier-Stokes equations are solved by applying the finite element method with least square Galerkin’s scheme using the commercial software COMSOL MultiPhysics 5.4. In the first step, results are contrasted by measuring the stream-wise velocity at the exit wall of the channel with the asymptotic solution provided by Elder [1], which was built on the analysis of fluid flow through the single screen. In the 2nd step we are going to present the velocity contours with surface plot and pressure drop arrow plot in the whole domain vs the inclination of the screens. Finally, dragging forces are calculated at the three perforated plates in terms of angle. The research is significant because it contributed interpolated equations of the maximum velocity at the exit, maximum pressure in the domain and drag force applied by the single screen in terms of inclination.

Adhesives are gaining importance in different industries, but the planning of the bonding process is subject to a high degree of uncertainty caused by the complex flow behavior of adhesives. Therefor the shear-thinning behavior which characterizes many types of adhesives is integrated into the Implicit Incompressible Smoothed Particles Hydrodynamix (IISPH) approach, which is ideally suited for free surface flow scenarios through its mesh-less characteristics. While these particle-based methods are already being used in the real-time simulation of Newtonian fluids in computer graphics, their applicability in engineering disciplines and simulation of complex fluid flows still has to be tested. The Carreau model has already been validated experimentally for accurately portraying the shear-thinning behavior of adhesives. In this work the Carreau model is integrated into the IISPH solver and the simulation results are compared to an analytical solution of the Poiseuille pipe flow. This approach can then be applied to lower the uncertainty in the early phase of manufacturing planning and for simulation-based optimization approaches involving rheological flow behavior.

This work is devoted to a theoretical and numerical study of a flow model in a heat exchanger cooled by two fluids. Assimilated to a vertical channel, the exchanger is divided in two immiscible regions separated by so thin plate made of high thermal conductivity material. The first region is filled with non-Newtonian micropolar fluid. The second region is filled with Newtonian fluid. The convective flow is due to the temperature gradient-between two walls of the channel–it’s also affected by a constant transverse magnetic field. This phenomenon is assumed as a mathematical model and developed. The terms of magnetic, viscous, and microrotation dissipations constituted the focal points of this work which present a numerical approach for some reasons. Firstly, to observe the interaction between these terms while running the dimensionless equations of balance. secondly, to examine the behavior of these terms while varying different obtained parameters. In addition, to study the effect of these terms and the dimensionless numbers and parameters on fluids flow. Finally, The investigation of the suggested model has allowed the appearance of certain dimensionless parameters and numbers such as the parameter of micropolarity, Prandtl number, the mixed convection parameter, the magnetic parameter, and Eckert number etc. The obtained results have been exploited and discussed.

It’s known that the properties of viscoelastic fluid are very different to Newtonian fluid. In this paper, the influence of polymer additive on flow past a bluff body is discussed. The commercial software Fluent as well as its secondary development is employed to describe the viscoelastic fluid flow, which is modeled by Oldroyd-B constitutive equations. Turbulence model is evaluate by Large eddy simulation as well as other frequently used two-equations model, which shown k-w SST is much better than standard K-e turbulent model. The numerical results indicate that the drag of slender body can be reduced by the polymer additives. while at high Weissenberg number, the drag force can be enhanced. The existence of elastic stress is active to suppress the turbulence fluctuations and keep the fluid flow in a more regular way.

The Oldroyd-B constitutive model is widely used for describing the viscoelastic behavior of the blood. However, there is sill a lack of blood flow simulations using non-Newtonian models, hence, a poor understanding of many cardiovascular diseases, mainly, atherosclerosis. In this paper, we intent to realize numerical computations of blood flow through arteries with the presence of a stenosis. We used the Newton iterations to deal with the nonlinear and coupled system of equations that includes the steady Navier-Stokes equations and the Oldroyd-B constitutive equations for viscolelastic fluids. The velocity and pressure field are calculated using the mixed finite elements discretization of the two dimensional spacial parameters. The numerical simulations are realized for a complex geometry of the flow domain with the existence of an arterial stenosis with fixed form. We demonstrated from the obtained results that the fluid behavior differs the Newtonian fluids and gives more realistic understanding of blood flow. Also, we showed the clear effect of stenosis shape and fluid model parameters on the blood flow. The presented study gives more insights on the understanding of blood flow behavior with the presence of various arterial diseases by the variation of different fluid and geometry parameters.

Transverse magnetic field is applied externally on a tapered stenosed artery by considering blood flow as two-flow model, Newtonian in peripheral region and nonNewtonian in core region. The pulsatile flow of blood in peripheral region is considered as Bingham Plastic model and the flow in core region is considered as Herschel-Bulkley model. Dimensionless mathematical model (system of non linear differential equations) is formulated and solved using one of the most advantageous methods, finite difference method. The expressions for important flow characteristics axial velocity, volumetric flow rate and wall shear stress are derived to analyze the effect of magnetic field, tapering angle, hematocrit and time component. Matlab 7.10.0 is used for mathematical simulation. It is found that all the flow characteristics are affected in stenosed artery and magnetic field helps to regulate the flow up to some extent.

The number of chemical processes transferred from a batch-wise approach to continuous flow is increasing, due to several advantages of continuous over batch: processes can be operated at more extreme conditions, resulting in higher speed and efficiency. Thus it is critical to evaluate key performance indicators real-time and in-line. For fluid handling processes like mixing and filling, the viscosity of the process fluid is a critical parameter. Also, for non-Newtonian fluids the viscosity varies with the shear rate. Hence the measured rheology is affected by intrusive sensor designs. Moreover, in view of fouling prevention and safety, the pipe wall should not be punctured. We propose a new concept to measure the viscosity as a function of shear rate by measuring the liquid velocity profile in and the pressure drop over the sensor. The concept is in-line, real-time, does not puncture the pipe wall and is non-intrusive. Here, we report on the development and performance of the tomographic ultrasonic velocity meter, which is part of said concept. The device consisted of 9 transducers distributed along the outer surface of a pipe. Tomographic time delay inversion was used to extract the liquid velocity profiles. The performance of the entire measurement chain was predicted using simulations. The transfer functions and acoustic wave fields were measured using a hydrophone setup. The device was tested with water and a high viscosity Newtonian liquid. The sensor successfully measured liquid velocity profiles.

In this work, we present a two-dimensional (2D) numerical model to describe the phenomenon of the flow in air plasma actuator, comprising two plane parallel electrodes separated by a dielectric layer.The simulation is developed through the use of the COMSOL software. We are interested in the development of gas flow model, in the studied actuator as a function of time, according to the fundamental Navier-stokes equations which govern the Newtonian fluid displacement. We studied the flow of gas with different actuator configurations, with initial conditions and well-defined boundaries conditions.The results obtained provide the velocity flow distribution and profile. The different geometries and initial velocity values affect the exit velocity of the flowing gas in the actuator. We have seen that the velocity is maximal on the upper electrode meaning that the electrode plays an important role in increasing the speed.

We present here an update of the JILA (Parks-Faller) 2010 determination of the Newtonian Constant of gravitation (big $\pmb{G}$ ). Due to an Abbe error that was unaccounted for in the initial analysis, we adjust our value of the gravitational constant $\pmb{G}$ from $\pmb{(6.67234\pm\ 0.00014) \times 10^{-11}\text{m}^{3}\text{kg}^{-1}\text{s}^{-2}}$ to $\pmb{(6.67296\pm 0.00022)\times 10^{-11}\text{m}^{3}\text{kg}^{-1}\text{s}^{-2}}$ . We discuss the source of the error and how it can be avoided in future iterations of this experiment.

This paper investigates the predictive capabilities of numerical simulation for addressing the actual operation of the hydraulic system of a filling machine for beverage packaging processes. The lumped and distributed parameter approach is compared to the full CFD simulation of the filling system and the accuracy of the results obtained is assessed in case of Newtonian and non-Newtonian fluids. First, the 0D-1D model of the complete hydraulic system of the machine filling process is constructed and validated against experimental measurements carried out using water as an operating fluid. Afterward, a combined 1D/3D simulation is carried out in order to simulate the real control strategy of the machine as well as to accurately determine the flow dynamic within the piping. Finally, the two approaches are confronted when using a non-Newtonian fluid and their advantages and limitations are outlined.

We have measured the Newtonian gravitational constant $G$ by using high-Q silica fibers with time-of-swing method. A series of improvements have been adopted to reduce the large corrections and uncertainties.

The study of non-modal amplification of distributed body forces in channel flows of viscoelastic fluids has provided useful insight into the mechanisms that may govern the initial stages of transition to elastic turbulence. However, distributed body forces are not easy to implement in experiments and there is a need to examine amplification of localized body forces. In this work, we use the linearized governing equations to examine such amplification in channel flow of viscoelastic fluids. We first identify the wall-normal location at which the impulsive excitations experience the largest amplification and then analyze the kinetic energy of the fluctuations and the resulting flow structures. For a viscoelastic fluid at low Reynolds numbers, the largest amplification occurs for impulses located near the channel wall. Flow structures that evolve from the localized body force at the optimal location stretch out in the streamwise direction in a viscoelastic fluid, unlike a Newtonian fluid in which disturbances merely diffuse in space due to low inertia. For viscoelastic fluids, we observe the development of vortical structures away from the source of impulsive excitation. This feature is less prominent in Newtonian fluids and it may provide a mechanism for triggering the initial stages of transition to elastic turbulence.

This paper introduces microrobot swimming of two bead ‘microsnowman’ swimmers inside synthetic mucus solutions. In Newtonian fluids, two beads bonded together would be unable to swim in low Reynolds number environments due to their apparent symmetry. The non-Newtonian interactions and heterogeneity of synthetic mucus allow microsnowman structures to maneuver under actuation from rotating magnetic fields without this geometric requirement. Two experiments were carried out in this paper, the first determined the directional controllability of these microsnowman swimmers inside synthetic mucus, while the other analyzed their velocity response to increasing frequency. The results indicate that microsnowman swimmers can swim omnidirectionally, however, their trajectories were offset due to self-generated internal flows. The velocity of the microsnowman swimmers increased linearly with frequency and were successful in overcoming small internal flows within the surrounding medium.

We study dynamics of a particle moving along a gantline with ends fixed on endpoints of an extended space station which mass center describes a circular orbit in the central Newtonian force field. We restrict to the case of gravitationally oriented station, in other words, we suppose that the station is directed on the attracting center throughout the motion. Assuming that the gantline is weightless and unstretchable tether that realizes unilateral constraint, we establish that spacial motions of the particle are librations near the orbit plane generally. Such librations might be regular, including periodic ones, or chaotic. We note that, in general case, the gantline remains taut all the time for regular motions only.

This paper presents the design, development and implementation of a novel, high power hexapole magnetic tweezer system for $3\mathbf{D}$ micromanipulations. Six tapering-tipped magnetic poles are deployed in a tilted Cartesian coordinate system, with an electromagnetic coil on each for actuation, connected by two $3\mathbf{D}$ printed magnetic yokes to form a double layer structure. The power source is integrated to the magnetic tweezer system through a control algorithm on the software level; image processing was used for experiment analysis. Because of the high magnetic field that the magnetic coils can generate, the working space in the system is relatively larger than other similar designs, which provides better performance on microscale robotic swimmer manipulations. Simulations and experiments performed in this paper demonstrate the agile and powerful manipulation of microswimmers with desired control input to follow complex trajectories, avoid obstacles and move against micro-flow in the samples. We prove that the developed hexapole magnetic tweezer has enough power and controllability to guide microswimmers in Newtonian and Non-Newtonian fluid environments. The system will be optimized continuously and implemented into cell penetration experiments. Finally, the application will be deployed into in vivo based environments.

A mathematical model is set up to describe natural convection in a two-layer system with effects of a plane shear flows and a constant flux heating in the case of a viscoelastic fluid. Through theoretical analysis and numerical simulation, the results will be obtained to explain and predict the physical phenomena of thermal instability. A linear stability analysis will be used to get eigenvalue problems for a plane shear flow. Then, a spectral method will be adopted to compute the neutral curves in thermal convection with the effects of shear flows and viscoelastic fluids. With the help of numerical simulation, it shows that neutral curves have a bi-modal nature for a proper fluid-porous depth ratio. Transverse rolls generated by shear flows are studied as well as longitudinal rolls. The effects of viscoelastic fluids on thermal instability will also be investigated in this paper. For Newtonian fluids, longitudinal rolls always set in before transvers rolls. Transvers rolls under the effects of viscoelastic fluids may be observed early in the flow phenomena.

Acoustic streaming is a promising way for transporting fluid or particles suspended in a fluid in lab-on-a-chip devices and microfluidics in general. In literature usually water is considered as the working medium. In this contribution we present a framework based on perturbation theory, which implements viscoelastic fluid behavior to the acoustic streaming effect expanding the applicability beyond simple Newtonian fluids. Numerical simulations were carried out by finite element analysis. As an example we consider the steady flow generated in a channel by acoustic streaming using the upper-convected Maxwell (UCM) model to describe the viscoelastic behavior.

This paper deals with the hemodynamic modeling in a carotid artery bifurcation with two laws - the laminar Newtonian and non Newtonian blood flow models- and two velocity inlet conditions - uniform and parabolic -. We assumed that blood flow is laminar and incompressible and the wall is rigid. From the artery geometry and the inlet velocity profile, four hemodynamic models of pulsatile flow were performed. These models were tested on a healthy subject data. The vascular model was reconstructed from Computed Tomography Angiography acquisition. The Doppler Ultrasound velocity data provided were considered as references. As a first conclusion, in the internal carotid artery, simulated velocities with non Newtonian law and uniform velocity inlet were the closest to US-Doppler measurements. However, in the external carotid artery, the closest model to US-Doppler measurements was non Newtonian law with parabolic inlet. Overall, Newtonian and non Newtonian blood flow models had a close behavior.

This present paper investigates the selective withdrawal of a viscous liquid, layered on top of another denser immiscible liquid. By positioning a capillary near the interface, a thin stream of the lower liquid becomes entrained, as the upper fluid is being pumped out of the vessel that contains it. The phenomenon is observed at a critical position of the capillary nozzle, relative to the interface, and above a critical flow rate. Two immiscible Newtonian liquids were used, water and mineral oil. Both flow focusing and columnary rise phenomena are investigated.

This work in vestigates the locomotion of helical robots in a low Reynolds number environment with two different rheological properties. We study the swimming characteristics of the robot during its transition from a Newtonian fluid to a viscoelastic environment. Our experimental results show that the helical robot causes shear thinning in gelatin with intermediate concentration. Therefore, its speed in gelatin is greater than that in silicone oil. The helical robot swims at maximum speed of 0.36 mm/s in silicone oil with viscosity of 5 Pa.s, and 0.22 mm/s, 0.71 mm/s, and 0.94 mm/s in gelatin with concentration of 2%, 3% and 4%, respectively, under the influence of two rotating dipole fields.

This paper deals with the blood rheology of curved vessel in the case of blood pulsation. To obtain the blood rheology, a three-phase incompressible homogeneous Newtonian viscous fluid consisting of plasma, red blood cells and white blood cells is considered as a blood. Computational fluid dynamics (CFD) model of the three-phase blood is established. To observe the variations of the blood velocity and wall shear stress (WSS) and vascular pressure, the blood rheology of curved vessel is analyzed using FLUENT software under the unsteady condition. In curved vessel, the velocity of the blood and the wall shear stress of the medial wall are both more than the lateral wall. On the other hand, the vascular pressure of the medial wall is less than the lateral wall in the systole. Therefore, in cardiovascular surgery, the blood rheology at the bend should be considered especially. This paper provides references for the implementation of cardiovascular surgery, the prediction of cardiovascular surgical devices performance and the prevention of cardiovascular diseases and cancer.

An experimental work has been devised to investigate the bore height and velocity on a dry flatbed as well as the impingement forces acting on a vertical structure subjected to both Newtonian (water) and non-Newtonian (kaolin clay at 20% concentration) fluids using physical modelling. Rheological analysis has shown that within the observed shear rate range (10 to 500 1/s), the kaolin mixture exhibits Herschel-Bulkley characteristics and the apparent viscosity of the fluid fitted well with the Sisko model. A dam-break system has been used to generate the Newtonian and non-Newtonian bores with the help of a 45 cm fluid depth reservoir located at one end of the wave flume. The experimental results shows that the maximum wave height produced by the non-Newtonian bore experiences up to 70% wave reduction along the length of the flume, as compared to 10% wave reduction for the Newtonian bores. While both fluids are subjected to supercritical flow range, the Reynolds number otherwise shows that the Newtonian bores are within turbulent range whereas for the case of non-Newtonian, the flow is laminar. Nevertheless, the pressure exerted by the non-Newtonian laminar flow (for the submerged part of the structure) is higher compared to that of the turbulent Newtonian bore. Bore surges and runup have shown to pose great influences on the overall pressure distribution along the height of the test model to which the Newtonian bores tends to generate larger surface fluxes compared to the non-Newtonian ones.

We have designed and fabricated a biomicroviscometer platform for measurement of microflows of biological fluids. The biomicroviscometer combines an optically clear biocompatible polydimethylsiloxane (PDMS) channel with on-chip integrated microfluidic differential pressure sensors and capabilities of modular channel geometries. This set-up allows for a direct measurement of the change in pressure and flow rate, increasing the overall accuracy of the measurement of viscosity and optical observation. We present an introduction of this combined method of measurement with different channel dimensions, using Newtonian and non-Newtonian fluids, and the corresponding calculations. This measurement technique has potential applications in measuring rheological properties at the micro level to further blood disease analysis, and lab-on-a-chip fabrication and analysis.

In this work we report a fiber optic sensor to measure the viscosity of Newtonian liquids. The sensor is made of a rectangular channel and two separate multimode optical fibers, which are properly inserted via through-holes provided at the extremities of the rectangular channel. Both the optical fibers do have a decladded zone for each to allow leakage of optical power from the zones when light is coupled into the fibers. When suitable liquid type flows inside the channel, liquid comes into contact with decladded zones thereby reducing leakage of optical power from the decladded zones. Under this condition, optical power levels available at output ends of the fibers undergo step change one after another with a time delay. And, the time delay is found to be proportional to viscosity of liquid and inclination of the channel through which liquid flows.

The problem of blood flow in a channel with Stenosis under the influence of an Unsteady Uniform Magnetic Field is studied. The Mathematical Model used for the formulation of the problem is consistent with the principles of Magnetohydrodynamics (MHD). Blood is considered as a Homogenous Newtonian fluid with an electrically conducting magnetic fluid. The Finite Volume discretization scheme in curvilinear coordinates is utilized for the discretization of the system of equations governing the MHD flow of blood. For the numerical solution of the problem, with a coupled, nonlinear system of PDEs, with suitable boundary conditions are solved using MATLAB. Results dealing with the velocity, pressure, and skin friction indicates the presence of the magnetic field influences considerably the fluid field.

Objective of this present article is to investigate into the linear stability characteristics of finite hydrodynamic journal bearing with micropolar lubrication in turbulent regime. The governing non-dimensional Reynolds equations for steady-state and dynamic pressures have been solved numerically to obtain film pressure distribution which is used to determine the linear stability characteristics in terms of critical mass parameter and whirl ratio. It is found that the higher stability threshold is obtained in micropolar lubrication than that in Newtonian lubrication. It is also observed that the threshold of stability tends to decrease with increase in Reynolds number and the whirl ratio at laminar flow condition has the lowest value.

The paper is concerned with the numerical modelling of the viscous steady flows in the vicinity of 3D micro-structures. The solutions are obtained for the Carreau generalized Newtonian model with negative flow index n. The main goal of the study is to investigate the shear banding formation between two rotating plates, in the presence of micro-pillars and micro-channels. The phenomenon is generated by the material instability of non-homogeneous complex fluids subjected to different shear rates under a constant shear stress. Simulations are performed in 3D configurations with the Ansys Fluent code.