scholarly journals Particles, Drops, and Bubbles Moving Across Sharp Interfaces and Stratified Layers

2020 ◽  
Vol 52 (1) ◽  
pp. 61-91 ◽  
Author(s):  
Jacques Magnaudet ◽  
Matthieu J. Mercier
Keyword(s):  
Relative Magnitude ◽  
Immiscible Fluids ◽  
The Body ◽  
Body Motion ◽  
Physical Parameters ◽  
Viscous Effects ◽  
Fluid Resistance ◽  
Wide Range ◽  
Deformable Bodies ◽  
Sharp Interfaces

Rigid or deformable bodies moving through continuously stratified layers or across sharp interfaces are involved in a wide variety of geophysical and engineering applications, with both miscible and immiscible fluids. In most cases, the body moves while pulling a column of fluid, in which density and possibly viscosity differ from those of the neighboring fluid. The presence of this column usually increases the fluid resistance to the relative body motion, frequently slowing down its settling or rise in a dramatic manner. This column also exhibits specific dynamics that depend on the nature of the fluids and on the various physical parameters of the system, especially the strength of the density/viscosity stratification and the relative magnitude of inertia and viscous effects. In the miscible case, as stratification increases, the wake becomes dominated by the presence of a downstream jet, which may undergo a specific instability. In immiscible fluids, the viscosity contrast combined with capillary effects may lead to strikingly different evolutions of the column, including pinch-off followed by the formation of a drop that remains attached to the body, or a massive fragmentation phenomenon. This review discusses the flow organization and its consequences on the body motion under a wide range of conditions, as well as potentialities and limitations of available models aimed at predicting the body and column dynamics.

scholarly journals A Computational Study on the Role of Parameters for Identification of Thyroid Nodules by Infrared Images (and Comparison with Real Data)

Sensors ◽  
2021 ◽  
Vol 21 (13) ◽  
pp. 4459
Author(s):  
José R. González ◽  
Charbel Damião ◽  
Maira Moran ◽  
Cristina A. Pantaleão ◽  
Rubens A. Cruz ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thyroid Nodules ◽  
Numerical Study ◽  
Computational Study ◽  
Internal Heat ◽  
Heat Transfer Process ◽  
The Body ◽  
Physical Parameters ◽  
Infrared Sensors ◽  
Wide Range

According to experts and medical literature, healthy thyroids and thyroids containing benign nodules tend to be less inflamed and less active than those with malignant nodules. It seems to be a consensus that malignant nodules have more blood veins and more blood circulation. This may be related to the maintenance of the nodule’s heat at a higher level compared with neighboring tissues. If the internal heat modifies the skin radiation, then it could be detected by infrared sensors. The goal of this work is the investigation of the factors that allow this detection, and the possible relation with any pattern referent to nodule malignancy. We aim to consider a wide range of factors, so a great number of numerical simulations of the heat transfer in the region under analysis, based on the Finite Element method, are performed to study the influence of each nodule and patient characteristics on the infrared sensor acquisition. To do so, the protocol for infrared thyroid examination used in our university’s hospital is simulated in the numerical study. This protocol presents two phases. In the first one, the body under observation is in steady state. In the second one, it is submitted to thermal stress (transient state). Both are simulated in order to verify if it is possible (by infrared sensors) to identify different behavior referent to malignant nodules. Moreover, when the simulation indicates possible important aspects, patients with and without similar characteristics are examined to confirm such influences. The results show that the tissues between skin and thyroid, as well as the nodule size, have an influence on superficial temperatures. Other thermal parameters of thyroid nodules show little influence on surface infrared emissions, for instance, those related to the vascularization of the nodule. All details of the physical parameters used in the simulations, characteristics of the real nodules and thermal examinations are publicly available, allowing these simulations to be compared with other types of heat transfer solutions and infrared examination protocols. Among the main contributions of this work, we highlight the simulation of the possible range of parameters, and definition of the simulation approach for mapping the used infrared protocol, promoting the investigation of a possible relation between the heat transfer process and the data obtained by infrared acquisitions.

A Comparison of Theoretical and Experimental Pressure Distributions on Bodies of Revolution

1980 ◽  
Vol 24 (01) ◽  
pp. 60-65
Author(s):  
A. J. Smits ◽  
S. P. Law ◽  
P. N. Joubert
Keyword(s):  
Calculation Method ◽  
The Body ◽  
Viscous Effects ◽  
Bodies Of Revolution ◽  
Pressure Distributions ◽  
Wide Range ◽  
The Right ◽  
Right Order ◽  
Axisymmetric Bodies ◽  
Experimental Pressure

A wide range of experimental pressure distributions along axisymmetric bodies was compared with the results of Landweber's potential flow calculation method. Apart from certain viscous effects, some discrepancies were found, and it is shown that blockage corrections are of the right order to account for these discrepancies. The calculation method was also used to show that the pressure distribution over the nose of the body is largely independent of the tail shape, and vice versa.

scholarly journals Falling styles of disks

2013 ◽  
Vol 719 ◽  
pp. 388-405 ◽  
Author(s):  
Franck Auguste ◽  
Jacques Magnaudet ◽  
David Fabre
Keyword(s):  
Complex Dynamics ◽  
Three Dimensional ◽  
Relative Magnitude ◽  
The Body ◽  
Fluid Inertia ◽  
Viscous Effects ◽  
Fluid Medium ◽  
Body Experiences ◽  
Set Up ◽  
Thin Disks

AbstractWe numerically investigate the dynamics of thin disks falling under gravity in a viscous fluid medium at rest at infinity. Varying independently the density and thickness of the disk reveals the influence of the disk aspect ratio which, contrary to previous belief, is found to be highly significant as it may completely change the route to non-vertical paths as well as the boundaries between the various path regimes. The transition from the straight vertical path to the planar fluttering regime is found to exhibit complex dynamics: a bistable behaviour of the system is detected within some parameter range and several intermediate regimes are observed in which, although the wake is unstable, the path barely deviates from vertical. By varying independently the body-to-fluid inertia ratio and the relative magnitude of inertial and viscous effects over a significant range, we set up a comprehensive map of the corresponding styles of path followed by an infinitely thin disk. We observe the four types of planar regimes already reported in experiments but also identify two additional fully three-dimensional regimes in which the body experiences a slow horizontal precession superimposed onto zigzagging or tumbling motions.

scholarly journals Path oscillations and enhanced drag of light rising spheres

2018 ◽  
Vol 841 ◽  
pp. 228-266 ◽  
Author(s):  
Franck Auguste ◽  
Jacques Magnaudet
Keyword(s):  
Density Ratio ◽  
Reynolds Numbers ◽  
Relative Magnitude ◽  
The Body ◽  
Sphere Diameter ◽  
Viscous Effects ◽  
Flow Parameters ◽  
Route To Chaos ◽  
Set Up ◽  
Equivalent Conditions

The dynamics of light spheres rising freely under buoyancy in a large expanse of viscous fluid at rest at infinity is investigated numerically. For this purpose, the computational approach developed by Mougin & Magnaudet (Intl J. Multiphase Flow, vol. 28, 2002, pp. 1837–1851) is improved to account for the instantaneous viscous loads induced by the translational and rotational sphere accelerations, which play a crucial role in the dynamics of very light spheres. A comprehensive map of the rise regimes encountered up to Reynolds numbers (based on the sphere diameter and mean rise velocity) of the order of $10^{3}$ is set up by varying independently the body-to-fluid density ratio and the relative magnitude of inertial and viscous effects in approximately 250 distinct combinations. These computations confirm or reveal the presence of several distinct periodic regions on the route to chaos, most of which only exist within a finite range of the sphere relative density and Reynolds number. The wake structure is analysed in these various regimes, evidencing the existence of markedly different shedding modes according to the style of path. The variation of the drag force with the flow parameters is also examined, revealing that only one of the styles of path specific to very light spheres yields a non-standard drag behaviour, with drag coefficients significantly larger than those measured on a fixed sphere under equivalent conditions. The outcomes of this investigation are compared with available experimental and numerical results, evidencing points of consensus and disagreement.

Creating the Wind

2020 ◽  
Vol 2 (4) ◽  
pp. 14-31
Author(s):  
Élodie Dupey García
Keyword(s):  
Indigenous Communities ◽  
The Body ◽  
Historical Sources ◽  
Natural Behavior ◽  
Sensory Experiences ◽  
Identity And Agency ◽  
Wide Range ◽  
Late Postclassic ◽  
Comparative Examination ◽  
Meteorological Phenomenon

This article explores how the Nahua of late Postclassic Mesoamerica (1200–1521 CE) created living and material embodiments of their wind god constructed on the basis of sensory experiences that shaped their conception of this divinized meteorological phenomenon. In this process, they employed chromatic and design devices, based on a wide range of natural elements, to add several layers of meaning to the human, painted, and sculpted supports dressed in the god’s insignia. Through a comparative examination of pre-Columbian visual production—especially codices and sculptures—historical sources mainly written in Nahuatl during the viceregal period, and ethnographic data on indigenous communities in modern Mexico, my analysis targets the body paint and shell jewelry of the anthropomorphic “images” of the wind god, along with the Feathered Serpent and the monkey-inspired embodiments of the deity. This study identifies the centrality of other human senses beyond sight in the conception of the wind god and the making of its earthly manifestations. Constructing these deity “images” was tantamount to creating the wind because they were intended to be visual replicas of the wind’s natural behavior. At the same time, they referred to the identity and agency of the wind god in myths and rituals.

Chaos in body–vortex interactions

2010 ◽  
Vol 466 (2119) ◽  
pp. 1871-1891 ◽  
Author(s):  
Johan Roenby ◽  
Hassan Aref
Keyword(s):  
Body Shape ◽  
Mass Density ◽  
Relative Equilibrium ◽  
Large Body ◽  
Point Vortex ◽  
Cylindrical Body ◽  
The Body ◽  
Body Motion ◽  
Single Vortex ◽  
Vortex Interactions

The model of body–vortex interactions, where the fluid flow is planar, ideal and unbounded, and the vortex is a point vortex, is studied. The body may have a constant circulation around it. The governing equations for the general case of a freely moving body of arbitrary shape and mass density and an arbitrary number of point vortices are presented. The case of a body and a single vortex is then investigated numerically in detail. In this paper, the body is a homogeneous, elliptical cylinder. For large body–vortex separations, the system behaves much like a vortex pair regardless of body shape. The case of a circle is integrable. As the body is made slightly elliptic, a chaotic region grows from an unstable relative equilibrium of the circle-vortex case. The case of a cylindrical body of any shape moving in fluid otherwise at rest is also integrable. A second transition to chaos arises from the limit between rocking and tumbling motion of the body known in this case. In both instances, the chaos may be detected both in the body motion and in the vortex motion. The effect of increasing body mass at a fixed body shape is to damp the chaos.

Development and Validation of a New Scoring Tool to Evaluate the Clinical Evolution of Adult Patients with Nonsegmental Vitiligo

Dermatology ◽  
2021 ◽  
pp. 1-9
Author(s):  
María Luisa Peralta-Pedrero ◽  
Denisse Herrera-Bringas ◽  
Karla Samantha Torres-González ◽  
Martha Alejandra Morales-Sánchez ◽  
Fermín Jurado Santa-Cruz ◽  
...  
Keyword(s):  
Body Surface ◽  
Task Force ◽  
Intraclass Correlation ◽  
The Body ◽  
Response To Treatment ◽  
Similar Response ◽  
Clinical Evolution ◽  
Wide Range ◽  
Patient Reported ◽  
Extreme Groups

<b><i>Background:</i></b> Vitiligo has an unpredictable course and a variable response to treatment. Furthermore, the improvement of some vitiligo lesions cannot be considered a guarantee of a similar response to the other lesions. Instruments for patient-reported outcome measures (PROM) can be an alternative to measure complex constructions such as clinical evolution. <b><i>Objective:</i></b> The aim of this study was to validate a PROM that allows to measure the clinical evolution of patients with nonsegmental vitiligo in a simple but standardized way that serves to gather information for a better understanding of the disease. <b><i>Methods:</i></b> The instrument was created through expert consensus and patient participation. For the validation study, a prospective cohort design was performed. The body surface area affected was measured with the Vitiligo Extension Score (VES), the extension, the stage, and the spread by the evaluation of the Vitiligo European Task Force assessment (VETFa). Reliability was determined with test-retest, construct validity through hypothesis testing, discriminative capacity with extreme groups, and response capacity by comparing initial and final measurements. <b><i>Results:</i></b> Eighteen semi-structured interviews and 7 cognitive interviews were conducted, and 4 dermatologists were consulted. The instrument Clinical Evolution-Vitiligo (CV-6) was answered by 119 patients with a minimum of primary schooling. A wide range was observed in the affected body surface; incident and prevalent cases were included. The average time to answer the CV-6 was 3.08 ± 0.58 min. In the test-retest (<i>n</i> = 53), an intraclass correlation coefficient was obtained: 0.896 (95% CI 0.82–0.94; <i>p</i> &#x3c; 0.001). In extreme groups, the mean score was 2 (2–3) and 5 (4–6); <i>p</i> &#x3c; 0.001. The initial CV-6 score was different from the final one and the change was verified with VES and VETFa (<i>p</i> &#x3c; 0.05, <i>n</i> = 92). <b><i>Conclusions:</i></b> The CV-6 instrument allows patient collaboration, it is simple and brief, and it makes it easier for the doctor to focus attention on injuries that present changes at the time of medical consultation.

scholarly journals Hydromechanics of low-Reynolds-number flow. Part 2. Singularity method for Stokes flows

1975 ◽  
Vol 67 (4) ◽  
pp. 787-815 ◽  
Author(s):  
Allen T. Chwang ◽  
T. Yao-Tsu Wu
Keyword(s):  
Exact Solutions ◽  
Stokes Flow ◽  
Fundamental Solutions ◽  
The Body ◽  
Circular Cylinders ◽  
Geometrical Parameters ◽  
Flow Problems ◽  
Singularity Method ◽  
Wide Range ◽  
Body Shapes

The present study further explores the fundamental singular solutions for Stokes flow that can be useful for constructing solutions over a wide range of free-stream profiles and body shapes. The primary singularity is the Stokeslet, which is associated with a singular point force embedded in a Stokes flow. From its derivatives other fundamental singularities can be obtained, including rotlets, stresslets, potential doublets and higher-order poles derived from them. For treating interior Stokes-flow problems new fundamental solutions are introduced; they include the Stokeson and its derivatives, called the roton and stresson.These fundamental singularities are employed here to construct exact solutions to a number of exterior and interior Stokes-flow problems for several specific body shapes translating and rotating in a viscous fluid which may itself be providing a primary flow. The different primary flows considered here include the uniform stream, shear flows, parabolic profiles and extensional flows (hyper-bolic profiles), while the body shapes cover prolate spheroids, spheres and circular cylinders. The salient features of these exact solutions (all obtained in closed form) regarding the types of singularities required for the construction of a solution in each specific case, their distribution densities and the range of validity of the solution, which may depend on the characteristic Reynolds numbers and governing geometrical parameters, are discussed.

scholarly journals Polymer-Drug Conjugates as Nanotheranostic Agents

2021 ◽  
Vol 2 (1) ◽  
pp. 63-81
Author(s):  
Sajana Manandhar ◽  
Erica Sjöholm ◽  
Johan Bobacka ◽  
Jessica M. Rosenholm ◽  
Kuldeep K. Bansal
Keyword(s):  
Drug Delivery ◽  
Drug Release ◽  
Treatment Options ◽  
The Body ◽  
Drug Conjugates ◽  
Imaging Characteristics ◽  
Wide Range ◽  
Systemic Side Effects ◽  
Theranostic Agents ◽  
The Stability

Since the last decade, the polymer-drug conjugate (PDC) approach has emerged as one of the most promising drug-delivery technologies owing to several benefits like circumventing premature drug release, offering controlled and targeted drug delivery, improving the stability, safety, and kinetics of conjugated drugs, and so forth. In recent years, PDC technology has advanced with the objective to further enhance the treatment outcomes by integrating nanotechnology and multifunctional characteristics into these systems. One such development is the ability of PDCs to act as theranostic agents, permitting simultaneous diagnosis and treatment options. Theranostic nanocarriers offer the opportunity to track the distribution of PDCs within the body and help to localize the diseased site. This characteristic is of particular interest, especially among those therapeutic approaches where external stimuli are supposed to be applied for abrupt drug release at the target site for localized delivery to avoid systemic side effects (e.g., Visudyne®). Thus, with the help of this review article, we are presenting the most recent updates in the domain of PDCs as nanotheranostic agents. Different methodologies utilized to design PDCs along with imaging characteristics and their applicability in a wide range of diseases, have been summarized in this article.

scholarly journals Self-rechargeable cardiac pacemaker system with triboelectric nanogenerators

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Hanjun Ryu ◽  
Hyun-moon Park ◽  
Moo-Kang Kim ◽  
Bosung Kim ◽  
Hyoun Seok Myoung ◽  
...  
Keyword(s):  
Medical Devices ◽  
Mechanical Energy ◽  
Cardiac Pacemaker ◽  
Operation Time ◽  
Lithium Ion ◽  
The Body ◽  
Body Motion ◽  
Triboelectric Nanogenerator ◽  
Implantable Medical Devices ◽  
Energy Harvesters

AbstractSelf-powered implantable devices have the potential to extend device operation time inside the body and reduce the necessity for high-risk repeated surgery. Without the technological innovation of in vivo energy harvesters driven by biomechanical energy, energy harvesters are insufficient and inconvenient to power titanium-packaged implantable medical devices. Here, we report on a commercial coin battery-sized high-performance inertia-driven triboelectric nanogenerator (I-TENG) based on body motion and gravity. We demonstrate that the enclosed five-stacked I-TENG converts mechanical energy into electricity at 4.9 μW/cm3 (root-mean-square output). In a preclinical test, we show that the device successfully harvests energy using real-time output voltage data monitored via Bluetooth and demonstrate the ability to charge a lithium-ion battery. Furthermore, we successfully integrate a cardiac pacemaker with the I-TENG, and confirm the ventricle pacing and sensing operation mode of the self-rechargeable cardiac pacemaker system. This proof-of-concept device may lead to the development of new self-rechargeable implantable medical devices.

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