Fluids最新文献 - Book学术

Interrupter Technique Revisited: Building an Experimental Mechanical Ventilator to Assess Respiratory Mechanics in Large Animals 重温中断器技术：构建实验性机械通风机，评估大型动物的呼吸力学状况

IF 1.9

Fluids Pub Date : 2024-06-14 DOI: 10.3390/fluids9060142

C. Zilianti, Erfan Bashar, Anna Kyriakoudi, Matteo Pecchiari

{"title":"Interrupter Technique Revisited: Building an Experimental Mechanical Ventilator to Assess Respiratory Mechanics in Large Animals","authors":"C. Zilianti, Erfan Bashar, Anna Kyriakoudi, Matteo Pecchiari","doi":"10.3390/fluids9060142","DOIUrl":"https://doi.org/10.3390/fluids9060142","url":null,"abstract":"Large animals are increasingly used as experimental models of respiratory diseases. Precise characterization of respiratory mechanics requires dedicated equipment with specific characteristics which are difficult to find together in the same commercial device. In this work, we describe building and validation of a computer-controlled ventilator able to perform rapid airways occlusions during constant flow inflations followed by a prolonged inspiratory hold. A constant airflow is provided by a high pressure source (5 atm) connected to the breathing circuit by three proportional valves. The combined action of three 2-way valves produces the phases of the breath. During non-inspiratory breath phases, airflow is diverted to a flowmeter for precise feedback regulation of the proportional valves. A computer interface enables the user to change the breathing pattern, trigger test breaths or run predetermined breaths sequences. A respiratory system model was used to test the ability of the ventilator to correctly estimate interrupter resistance. The ventilator was able to produce a wide range of constant flows (0.1–1.6 L/s) with the selected timing. Errors in the measurement of interrupter resistance were small (1 ± 5% of the reference value). The device described reliably estimated interrupter resistance and can be useful as a measuring tool in large animal research.","PeriodicalId":12397,"journal":{"name":"Fluids","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141339832","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Three-Dimensional Long-Wave Instability of an Evaporation/Condensation Film 蒸发/凝结薄膜的三维长波不稳定性

IF 1.9

Fluids Pub Date : 2024-06-14 DOI: 10.3390/fluids9060143

Weiyang Jiang, Ruiqi Huang, Qiang Yang, Zijing Ding

引用次数: 0

Valveless Pumping with an Unsteady Stenosis in an Open Tank Configuration 开式水槽配置中的无阀泵送与非稳定性狭窄

IF 1.9

Fluids Pub Date : 2024-06-12 DOI: 10.3390/fluids9060141

C. Manopoulos, D. Mathioulakis

{"title":"Valveless Pumping with an Unsteady Stenosis in an Open Tank Configuration","authors":"C. Manopoulos, D. Mathioulakis","doi":"10.3390/fluids9060141","DOIUrl":"https://doi.org/10.3390/fluids9060141","url":null,"abstract":"This work examines the beneficial role of an unsteady stenosis, not driven by any external energy source, as a means for augmenting the flow rate of a valveless pump in a hydraulic loop, including an open tank. In contrast to our previous work, in which the concept of the latter stenosis was introduced for the first time in a horizontal closed loop, here, gravity was taken into account. The stenosis neck cross-sectional area was controlled by the fluid pressure and the opposing force applied externally by a spring of adjustable tension. A pincher compressed and decompressed a part of the pump’s flexible tube periodically, with frequencies from 5 Hz to 11 Hz and compression ratios Ab from 24% to 65%. The presence of the stenosis increased the net flow rate by 19 times for Ab = 24% and 6.3 times for Ab = 38%; whereas for Ab = 65%, the flow rates were comparable. The volumetric efficiency varied from 30% to 40% under the presence of the stenosis, and from 2% to 20% without the stenosis. The role of the stenosis was to cause a unidirectional flow, opening during tube compression and closing during decompression. The pressure amplitudes along the flexible tube increased towards the rigid–flexible tube junction (as a result of the wave reflections), which were found to be significantly attenuated by the presence of the stenosis, whereas the flow rate pulsations did not exceed 10% of the mean at the peak net flow rates.","PeriodicalId":12397,"journal":{"name":"Fluids","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141350512","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Analytical Solution for Transient Electroosmotic and Pressure-Driven Flows in Microtubes 微管中瞬态电渗流和压力驱动流的分析解决方案

IF 1.9

Fluids Pub Date : 2024-06-11 DOI: 10.3390/fluids9060140

Yu Feng, H. Yi, Ruguan Liu

{"title":"Analytical Solution for Transient Electroosmotic and Pressure-Driven Flows in Microtubes","authors":"Yu Feng, H. Yi, Ruguan Liu","doi":"10.3390/fluids9060140","DOIUrl":"https://doi.org/10.3390/fluids9060140","url":null,"abstract":"This study focuses on deriving and presenting an infinite series as the analytical solution for transient electroosmotic and pressure-driven flows in microtubes. Such a mathematical presentation of fluid dynamics under simultaneous electric field and pressure gradients leverages governing equations derived from the generalized continuity and momentum equations simplified for laminar and axisymmetric flow. Velocity profile developments, apparent slip-induced flow rates, and shear stress distributions were analyzed by varying values of the ratio of microtube radius to Debye length and the electroosmotic slip velocity. Additionally, the “retarded time” in terms of hydraulic diameter, kinematic viscosity, and slip-induced flow rate was derived. A simpler polynomial series approximation for steady electroosmotic flow is also proposed for engineering convenience. The analytical solutions obtained in this study not only enhance the fundamental understanding of the electroosmotic flow characteristics within microtubes, emphasizing the interplay between electroosmotic and pressure-driven mechanisms, but also serve as a benchmark for validating computational fluid dynamics models for electroosmotic flow simulations in more complex flow domains. Moreover, the analytical approach aids in the parametric analysis, providing deeper insights into the impact of physical parameters on electroosmotic and pressure-driven flow behavior, which is critical for optimizing device performance in practical applications. These findings also offer insightful implications for diagnostic and therapeutic strategies in healthcare, particularly enhancing the capabilities of lab-on-a-chip technologies and paving the way for future research in the development and optimization of microfluidic systems.","PeriodicalId":12397,"journal":{"name":"Fluids","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141357821","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Stochastic Equations of Hydrodynamic Theory of Plasma 等离子体流体力学理论的随机方程

IF 1.9

Fluids Pub Date : 2024-06-07 DOI: 10.3390/fluids9060139

Artur V. Dmitrenko

{"title":"Stochastic Equations of Hydrodynamic Theory of Plasma","authors":"Artur V. Dmitrenko","doi":"10.3390/fluids9060139","DOIUrl":"https://doi.org/10.3390/fluids9060139","url":null,"abstract":"Stochastic equations of the hydrodynamic theory of plasma are presented in relation to strong external fields. It is shown that the use of these stochastic equations makes it possible to obtain new theoretical solutions for plasma as a result of its heating in a strong external electric field. Theoretical solutions for the conductivity of turbulent plasma when heated in an external electric field of 100 V/cm are considered. Calculated values for the electron drift velocity, electron mobility, electron collision frequency, and the Coulomb logarithm in the region of strong electric fields are obtained. Here we consider experiments on turbulent heating of hydrogen plasma in the range of electric field strength of 100 < E < 1000. The calculated dependences of plasma conductivity are in satisfactory agreement with experimental data for heating plasma in a strong electric field. It is shown that the plasma turbulence in the region of strong electric fields E ~1000 V/cm is close to 100%. For the first time, it is confirmed that the derived dependences for collision frequency, drift velocity, and other values include the degree of turbulence of plasma, which makes it possible to correctly describe experimental data for heating plasma even with strong electric fields. In addition, it was determined that the scatter of experimental data may be associated with the variability of the function in the expression for the heat flux density. For the first time, it is shown theoretically that the experimentally determined fact of the possibility of the existence of an approximate constancy of plasma conductivity in the region E = 100–1000 V/cm can occur with an error of ~30%. The results show significant advantages of the stochastic hydrodynamic plasma theory over other methods that are not yet able to satisfactorily as well as qualitatively and quantitatively predict long-known experimental data while taking into account the degree of turbulence.","PeriodicalId":12397,"journal":{"name":"Fluids","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141372281","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Correction Factors for the Use of 1D Solution Methods for Dynamic Laminar Liquid Flow through Curved Tubes 使用一维求解方法解决液体在弯曲管道中的动态层流问题的修正系数

IF 1.9

Fluids Pub Date : 2024-06-06 DOI: 10.3390/fluids9060138

T. Wiens

引用次数: 0

Advanced RBF Methods for Mapping Aerodynamic Loads onto Structures in High-Fidelity FSI Simulations 在高保真 FSI 模拟中将空气动力载荷映射到结构上的先进 RBF 方法

IF 1.9

Fluids Pub Date : 2024-06-06 DOI: 10.3390/fluids9060137

A. Chiappa, Andrea Lopez, C. Groth

引用次数: 0

N-Symmetric Interaction of N Hetons, II: Analysis of the Case of Arbitrary N N 个赫子的 N 对称相互作用，II：任意 N 的情况分析