C. Zilianti, Erfan Bashar, Anna Kyriakoudi, Matteo Pecchiari
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.
{"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}
This paper explores the stability and dynamics of a three-dimensional evaporating/condensing film while falling down a heated/cooled incline. Instead of using the Hertz–Knudsen–Langmuir relation, a more comprehensive phase-change boundary condition is employed. A nonlinear differential equation is derived based on the Benny-type equation, which takes into account gravity, energy transport, vapor recoil, effective pressure, and evaporation. The impact of effective pressure and vapor recoil on instability is studied using a linear stability analysis. The results show that spanwise perturbations can amplify the destabilizing effects of vapor recoil, leading to instability. Energy transport along the interface has almost no effect on the stability of the system, but it does influence the linear wave speed. Nonlinear evolution demonstrates that, in contrast to the vapor recoil effect, effective pressure can improve stability and delay film rupture. The self-similar solution demonstrates that the minimal film thickness decreases as (tr−t)1/2 and (tr−t)1/3 under the dominance of evaporation and vapor recoil, respectively.
{"title":"Three-Dimensional Long-Wave Instability of an Evaporation/Condensation Film","authors":"Weiyang Jiang, Ruiqi Huang, Qiang Yang, Zijing Ding","doi":"10.3390/fluids9060143","DOIUrl":"https://doi.org/10.3390/fluids9060143","url":null,"abstract":"This paper explores the stability and dynamics of a three-dimensional evaporating/condensing film while falling down a heated/cooled incline. Instead of using the Hertz–Knudsen–Langmuir relation, a more comprehensive phase-change boundary condition is employed. A nonlinear differential equation is derived based on the Benny-type equation, which takes into account gravity, energy transport, vapor recoil, effective pressure, and evaporation. The impact of effective pressure and vapor recoil on instability is studied using a linear stability analysis. The results show that spanwise perturbations can amplify the destabilizing effects of vapor recoil, leading to instability. Energy transport along the interface has almost no effect on the stability of the system, but it does influence the linear wave speed. Nonlinear evolution demonstrates that, in contrast to the vapor recoil effect, effective pressure can improve stability and delay film rupture. The self-similar solution demonstrates that the minimal film thickness decreases as (tr−t)1/2 and (tr−t)1/3 under the dominance of evaporation and vapor recoil, respectively.","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":"141341650","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}
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.
{"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}
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.
{"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}
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.
介绍了等离子体流体力学理论中与强外电场有关的随机方程。结果表明，使用这些随机方程可以获得等离子体在强外电场中加热时的新理论解。研究考虑了湍流等离子体在 100 V/cm 的外电场中加热时的电导率理论解。得出了强电场区域内电子漂移速度、电子迁移率、电子碰撞频率和库仑对数的计算值。在此，我们考虑了在 100 < E < 1000 的电场强度范围内氢等离子体的湍流加热实验。等离子体电导率的计算值与在强电场中加热等离子体的实验数据完全一致。研究表明，在强电场 E ~1000 V/cm 区域，等离子体湍流接近 100%。首次证实推导出的碰撞频率、漂移速度和其他值的依赖关系包括等离子体的湍流程度，这使得正确描述在强电场下加热等离子体的实验数据成为可能。此外，还确定了实验数据的分散可能与热通量密度表达式中函数的变化有关。研究首次从理论上证明了实验所确定的事实，即在 E = 100-1000 V/cm 区域等离子体电导率可能存在近似常数，误差约为 30%。结果表明，随机流体动力等离子体理论与其他方法相比具有显著优势，其他方法还无法在考虑湍流程度的同时，令人满意地定性和定量预测已知的长期实验数据。
{"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}
The modeling of transient flows of liquids through tubes is required for studies in water hammer, switched inertance hydraulic converters, and noise reduction in hydraulic equipment. While 3D gridded computational fluid dynamics (CFD) methods exist for the prediction of dynamic flows and pressures in these applications, they are computationally costly, and it is more common to use 1D methods such as the method of characteristics (MOC), transmission line method (TLM), or frequency domain methods. These 1D methods give good approximations of results but require many orders of magnitude less computation time. While these tubes are typically curved or coiled in practical applications, existing 1D solution methods assume straight tubes, often with unknown deviation from the curved tube solution. This paper uses CFD simulations to determine the correction factors that can be used for existing 1D methods with curved tubes. The paper also presents information that can be used to help evaluate the expected errors resulting from this approximation.
{"title":"Correction Factors for the Use of 1D Solution Methods for Dynamic Laminar Liquid Flow through Curved Tubes","authors":"T. Wiens","doi":"10.3390/fluids9060138","DOIUrl":"https://doi.org/10.3390/fluids9060138","url":null,"abstract":"The modeling of transient flows of liquids through tubes is required for studies in water hammer, switched inertance hydraulic converters, and noise reduction in hydraulic equipment. While 3D gridded computational fluid dynamics (CFD) methods exist for the prediction of dynamic flows and pressures in these applications, they are computationally costly, and it is more common to use 1D methods such as the method of characteristics (MOC), transmission line method (TLM), or frequency domain methods. These 1D methods give good approximations of results but require many orders of magnitude less computation time. While these tubes are typically curved or coiled in practical applications, existing 1D solution methods assume straight tubes, often with unknown deviation from the curved tube solution. This paper uses CFD simulations to determine the correction factors that can be used for existing 1D methods with curved tubes. The paper also presents information that can be used to help evaluate the expected errors resulting from this approximation.","PeriodicalId":12397,"journal":{"name":"Fluids","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141377739","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}
The reliable exchange of data is a crucial issue for the loose coupling of computational fluid dynamics (CFD) and computational structural mechanics (CSM) modules in fluid–structure interaction (FSI) applications. This paper presents a comparison between two methods for mapping the traction field across mismatching grids, namely the RIBES method and the preCICE algorithm, both based on radial basis function (RBF) interpolation. The two methods demonstrate different degrees of control over balance preservation during mapping, with the RIBES algorithm exhibiting greater efficacy. Test benches are a parametric double curved geometry and a wind tunnel mock-up. In this second case, forces from mapping are used to load a CSM model to retrieve stress and displacement fields. Differences in FEM results are appreciable although not significant, showing a correlation between the accuracy of balance preservation during data mapping and the structural output.
{"title":"Advanced RBF Methods for Mapping Aerodynamic Loads onto Structures in High-Fidelity FSI Simulations","authors":"A. Chiappa, Andrea Lopez, C. Groth","doi":"10.3390/fluids9060137","DOIUrl":"https://doi.org/10.3390/fluids9060137","url":null,"abstract":"The reliable exchange of data is a crucial issue for the loose coupling of computational fluid dynamics (CFD) and computational structural mechanics (CSM) modules in fluid–structure interaction (FSI) applications. This paper presents a comparison between two methods for mapping the traction field across mismatching grids, namely the RIBES method and the preCICE algorithm, both based on radial basis function (RBF) interpolation. The two methods demonstrate different degrees of control over balance preservation during mapping, with the RIBES algorithm exhibiting greater efficacy. Test benches are a parametric double curved geometry and a wind tunnel mock-up. In this second case, forces from mapping are used to load a CSM model to retrieve stress and displacement fields. Differences in FEM results are appreciable although not significant, showing a correlation between the accuracy of balance preservation during data mapping and the structural output.","PeriodicalId":12397,"journal":{"name":"Fluids","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141380318","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}
Konstantin V. Koshel, M. Sokolovskiy, D. Dritschel, J. Reinaud
This paper seeks and examines N-symmetric vortical solutions of the two-layer geostrophic model for the special case when the vortices (or eddies) have vanishing summed strength (circulation anomaly). This study is an extension [Sokolovskiy et al. Phys. Fluids 2020, 32, 09660], where the general formulation for arbitrary N was given, but the analysis was only carried out for N=2. Here, families of stationary solutions are obtained and their properties, including asymptotic ones, are investigated in detail. From the point of view of geophysical applications, the results may help interpret the propagation of thermal anomalies in the oceans.
本文针对涡旋（或涡流）强度总和（环流异常）消失的特殊情况，寻找并研究了双层地转模型的 N 对称涡旋解。这项研究是对[Sokolovskiy 等人，Phys. Fluids 2020, 32, 09660]的扩展，[Sokolovskiy 等人，Phys. Fluids 2020, 32, 09660]给出了任意 N 的一般公式，但只对 N=2 进行了分析。在这里，我们得到了静止解系列，并详细研究了它们的特性，包括渐近特性。从地球物理应用的角度来看，这些结果可能有助于解释热异常在海洋中的传播。
{"title":"N-Symmetric Interaction of N Hetons, II: Analysis of the Case of Arbitrary N","authors":"Konstantin V. Koshel, M. Sokolovskiy, D. Dritschel, J. Reinaud","doi":"10.3390/fluids9060122","DOIUrl":"https://doi.org/10.3390/fluids9060122","url":null,"abstract":"This paper seeks and examines N-symmetric vortical solutions of the two-layer geostrophic model for the special case when the vortices (or eddies) have vanishing summed strength (circulation anomaly). This study is an extension [Sokolovskiy et al. Phys. Fluids 2020, 32, 09660], where the general formulation for arbitrary N was given, but the analysis was only carried out for N=2. Here, families of stationary solutions are obtained and their properties, including asymptotic ones, are investigated in detail. From the point of view of geophysical applications, the results may help interpret the propagation of thermal anomalies in the oceans.","PeriodicalId":12397,"journal":{"name":"Fluids","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141100345","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}
Oil transportation becomes much more complicated due to the solidification of paraffins in them at low temperatures and the resulting increase in oil viscosity. To solve this problem, special additives as pour point depressants (PPDs) are used to prevent the agglomeration of paraffin crystals. In this work, 15 PPDs were obtained and tested, consisting of a solution of polyethylene in hexane and also, in some cases, from magnetic nanoparticles (MNPs) extracted from coal fly ash. The most effective result was observed with a mixture of 0.25% polyethylene in hexane and 2% MNPs, which managed to lower the oil’s pour point from 18 °C to −17 °C.
{"title":"Novel Pour Point Depressants for Crude Oil Derived from Polyethylene Solution in Hexane and Coal Fly Ash","authors":"Kazim Nadirov, Manap Zhantasov, Tlek Ketegenov, Zhanna Nadirova, Aisulu Batkal, Kaster Kamunur, Gulmira Bimbetova, Rashid Nadirov","doi":"10.3390/fluids9060121","DOIUrl":"https://doi.org/10.3390/fluids9060121","url":null,"abstract":"Oil transportation becomes much more complicated due to the solidification of paraffins in them at low temperatures and the resulting increase in oil viscosity. To solve this problem, special additives as pour point depressants (PPDs) are used to prevent the agglomeration of paraffin crystals. In this work, 15 PPDs were obtained and tested, consisting of a solution of polyethylene in hexane and also, in some cases, from magnetic nanoparticles (MNPs) extracted from coal fly ash. The most effective result was observed with a mixture of 0.25% polyethylene in hexane and 2% MNPs, which managed to lower the oil’s pour point from 18 °C to −17 °C.","PeriodicalId":12397,"journal":{"name":"Fluids","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141104199","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}
Within river systems, the process of bed-forming is intricate, dynamic and is shaped by different factors [...]
在河流系统中，河床形成过程错综复杂、充满活力，并受到不同因素的影响[......]
{"title":"Environmental Hydraulics, Turbulence, and Sediment Transport, Second Edition","authors":"J. Pu, Manish Pandey, P. R. Hanmaiahgari","doi":"10.3390/fluids9060120","DOIUrl":"https://doi.org/10.3390/fluids9060120","url":null,"abstract":"Within river systems, the process of bed-forming is intricate, dynamic and is shaped by different factors [...]","PeriodicalId":12397,"journal":{"name":"Fluids","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141108737","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}
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