Fluid Characteristics Research Articles

Thermal full-field prediction of an air-cooled data center using a novel multi-scale approach based on POD and CFD coupling

A full-knowledge of the temperature distribution in a data center is crucial for the design and operation to avoid thermal failure. However, it is a great challenge to conduct full-field simulations using the computational fluid dynamics/heat transfer (CFD/HT) method due to the unacceptable computational cost caused by the multi-scale structure of data centers. In this paper, a novel multi-scale model based on POD and CFD coupling is proposed to predict the thermal and fluid characteristics in data centers from room scale to chip scale. The temperature and flow fields in an air-cooled data center are predicted and analyzed under the scales of room, server, IGBT and chip. Based on the CFD results of Room-Server level, 16 sets of design cases’ temperature fields for Server-IGBT level are compared using the POD and CFD methods, which shows that the maximum average absolute deviation and average relative deviation are 0.004 °C and 0.59%, respectively. Subsequently, three sets of off-design cases for Server-IGBT level and IGBT-Chip level are predicted using the aforementioned methods, yielding the maximum relative deviation 7.21% and 0.98%, respectively. The salient outcome is the remarkable 175-fold reduction in CPU processing time achieved with the POD model compared to traditional CFD simulations.

Optimizing the design of axial flow pump blades based on fluid characteristics

Non-physiological blood flow conditions in axial blood pumps lead to some complications, including hemolysis, platelet activation, thrombosis, and embolism. The high speed of the axial blood pump destroys large amounts of erythrocytes, thereby causing hemolysis and thrombosis. Thus, this study aims to reduce the vortices and reflux in the flow field by optimizing the axial blood pump. The axial blood pump and arterial flow field were modeled by the finite element method. The blood was assumed to be incompressible, turbulent, and Newtonian. The SST k–ω turbulence model was used. The frozen rotor method was also used to calculate the snapshot of motion. Many vortices and reflux exist in the flow field of the blood pump without optimization. The improved flow field had almost no vortex and reflux, thereby reducing the exposure time of blood. The optimized blood pump had little influence on the pressure field and shear stress field. The optimized blood pump mainly reduced the vortex, reflux, and the risk of thrombosis in the flow field. The flow field characteristics of an axial blood pump were studied, and the results showed the risk of thrombosis and hemolysis in the blood pump. In accordance with the relationship between the blade shape and the flow field, the blade of the blood pump was optimized, reducing the vortex and reflux of the flow field, as well as the risk of thrombosis.

Skarn Formation and Zn–Cu Mineralization in the Dachang Sn Polymetallic Ore Field, Guangxi: Insights from Skarn Rock Assemblage and Geochemistry

The Dachang is a world-class, super-giant Sn polymetallic ore field mainly composed of Zn–Cu ore bodies proximal to the granitic pluton and Sn polymetallic ore bodies distal to the granitic pluton. In this study, we used petrographic studies and major and trace element geochemistry with calc-silicates from the Zn–Cu ore bodies to constrain the physicochemical conditions of hydrothermal fluids during skarn rock formation and the evolution of ore-forming elements. Two skarn stages were identified based on petrographic observations: Prograde skarn rocks (Stage I), containing garnet, vesuvianite, pyroxene, wollastonite, and retrograde skarn rocks (Stage II), containing axinite, actinolite, epidote, and chlorite. The retrograde skarn rocks are closely associated with mineralization. The geochemical results show that the garnets in the Dachang ore field belong to the grossular–andradite solid solution, in which the early generation of garnet is mainly composed of grossular (average Gro72And25), while the later generation of garnet is mainly composed of andradite (average Gro39And59); the vesuvianites are Al-rich vesuvianites; the pyroxenes form a diopside–hedenbergite solid solution with a composition of Di3–86Hd14–96; the axinites are mainly composed of ferroaxinite; and the actinolites are Fe-actinolite. The mineral assemblage of the skarn rocks indicates that the ore-forming fluid was in a relatively reduced state in the early prograde skarn stage. As the ore-forming fluid evolved, the oxygen fugacity of the ore-forming fluid increased. During the final skarn stage, the ore-forming fluid changed from a relatively oxidized state to a reduced state. The skarn rocks have evolved from early Al-rich to late Fe-rich characteristics, indicating that the early ore-forming fluid was mainly magmatic exsolution fluid, which may mainly reflect the characteristics of magmatic fluids, and the late Fe-rich characteristics of the skarn rocks may indicate that the late hydrothermal fluid was strongly influenced by country rocks. Trace element analyses showed that the Sn content decreased from the prograde skarn stage to the retrograde skarn stage, indicating that Sn mineralization was not achieved by activating and extracting Sn from prograde skarn rocks by hydrothermal fluids. The significant enrichment of Sn in the magmatic hydrothermal fluid is a necessary condition for Sn mineralization. There are various volatile-rich minerals such as axinite, vesuvianite, fluorite, and tourmaline in the Dachang ore field, indicating that the ore-forming fluid contained extensive volatiles B and F, which may be the fundamental reason for the large-scale mineralization of the Dachang ore field.

Impact of variable fluid characteristics on MHD hybrid nanofluid (MgO+ZnO/H2O) flow over an exponentially elongated sheet with non-uniform heat generation

Variations in viscosity and thermal conductivity play a vital role in the manufacturing of glass fiber, ceramics, pharmaceuticals, and plastics, as well as in hot rolling, space technology, and high-temperature processes. This article investigates an electrically conducting hybrid nanofluid flowing across an exponentially extended sheet under variable fluid properties, such as thermal conductivity, viscosity, and non-uniform heat generation. In addition, the Prandtl number can vary inside the boundary layer and is an effective way to manage heat transfer and fluid flow. Furthermore, slip effects and suction at the boundary have been considered, and the hybrid nanofluid flow is also influenced by variations in viscous forces and viscous dissipation effects. The governing partial differential equations can be discretized into dimensionless ordinary differential equations using similarity transformations. The various important physical parameters have been presented in detail using diagrams. It is also observed that the skin friction of hybrid nanofluids is increased by up to 4.07% compared to nanofluids with suction. The presence of thermal radiation can enhance the energy Nusselt number of hybrid nanofluids by as much as 6.5%. Moreover, the variable Prandtl number is more effective than the constant Prandtl number in enhancing the heat transfer rate.

Mixing characteristics of high-viscosity fluids with laminar flow in a stirred tank with a fractal arranged perforated impeller

Fractal arranged perforated impeller (FAP impeller) was introduced to minimize the isolated mixing region and expand the chaotic mixing region for the mixing process of high-viscosity fluids with laminar flow. The mixing performance of FAP impeller and Rushton turbine were comparatively investigated with numerical simulation and experimental analysis. Results showed that the introduction of fractal arrangement perforated holes in the impeller blades resulted in lower power consumption, power number and mixing efficiency number, and higher values of largest Lyapunov exponent compared with conventional ones. The higher mixing efficiency could be obtained with an increase in fractal iteration number of FAP impeller. Meanwhile, the design of fractal arrangement perforated holes in the impeller blades could destroy the recirculation zone behind impeller blades, enhance the strain rate, and reduce the dimension of isolated mixing region compared with standard ones, and the aforementioned phenomena became more prominent with the increase of fractal iteration number of FAP impeller. In addition, it could be also found that fractal arrangement perforated holes in the impeller blades could enhance the strain rate and improve the fluid mixing efficiency as compared to horizontal-vertical arrangement perforated holes and a simple whole perforated hole in the impeller blades with equivalent cut area.

Cu-Graphene water-based hybrid nanofluids: synthesis, stability, thermophysical characterization, and figure of merit analysis

Hybrid nanofluids are emerging as an alternative to conventional heat transfer fluids and nanofluids for improving the thermal efficiency of heat exchanging devices synergistically due to their outstanding thermophysical properties associated because of the dispersion of different types of nanoparticles as compared to mono nanofluids. This will help in optimizing fluid characteristics in different flow regimes for several applications. However, enhancing the thermal energy efficiency of heat exchangers is challenging owing to the deprived stability of hybrid nanofluids at greater volume concentrations. This work concentrated on the synthesizing, thermophysical depiction, and thermal performance estimation of stable water-based Cu-graphene hybrid nanofluids using very low volume concentrations of Cu and graphene hybrid nanostructures. Cu-graphene hybrid nanofluid was successfully synthesized by dispersing the synthesized Cu and graphene nanostructures (keeping the Cu concentration constant at 0.04 vol % and varying the graphene concentration from 0.01 to 0.1 vol %) in water. Hybrid nanofluids display excellent stability against aggregation for up to 7 weeks, as proven by higher zeta potential values. Thermophysical characteristics of the prepared hybrid nanofluids were effectively measured. The thermal conductivity of Cu-graphene hybrid nanofluids shows exceptional enrichment (~ 35%) at minimal concentrations of hybrid nanostructures. Viscosity of the water-based hybrid nanofluids shows remarkable enhancement as compared to water and represents the increasing trend in viscosity of the base fluid with respect to the increase in concentration of hybrid nanostructures. The thermal and rheological properties of hybrid nanofluids are effectively validated with existing theoretical models. In addition, the specific heat and pumping power of Cu-graphene hybrid nanofluids with respect to the volume concentration of hybrid nanostructures are calculated using the existing theoretical equations. A figure of merit (FOM) analysis was conducted for the synthesized hybrid nanofluids to gauge thermal efficiency and evaluate the applicability of these hybrid nanofluids under laminar and turbulent flow conditions.

Numerical study of gas invasion law in fractured reservoirs

Gas invasion during the drilling process in fractured reservoirs poses challenges, affecting drilling efficiency and increasing costs. Therefore, it is crucial to effectively and accurately describe the flow characteristics of subsurface fluids. Addressing the issue of gas invasion in fractured reservoirs, this study considers the influence of matrix deformation and fracture aperture variation on fluid flow and establishes a mathematical model for coupled flow and solid deformation in fractured reservoirs. The numerical formulation of the mathematical model is derived using the finite element method. To better represent real reservoir conditions, discrete fractures are created using MATLAB, and numerical solutions are obtained using the commercial software COMSOL Multiphysics. The accuracy of the model is verified through a comparison between numerical and analytical solutions. This paper first explores the characteristics of fluid flow within a single fracture and rock deformation when encountering a fracture during drilling. It then compares the predictive capability of the coupled model with that of the uncoupled model in estimating gas invasion. Finally, the primary factors influencing gas invasion in fractured reservoirs are analyzed from the perspectives of rock matrix, fractures, and drilling operations.

Effect of pocket orientation on four pocket hybrid journal bearing operating with piezo-viscous polar lubricant

PurposeThe present paper aims to analyse the synergistic effect of pocket orientation and piezo-viscous-polar (PVP) lubrication on the performance of multi-recessed hybrid journal bearing (MHJB) system.Design/methodology/approachTo simulate the behaviour of PVP lubricant in clearance space of the MHJB system, the modified form of Reynolds equation is numerically solved by using finite element method. Galerkin’s method is used to obtain the weak form of the governing equation. The system equation is solved by Gauss–Seidal iterative method to compute the unknown values of nodal oil film pressure. Subsequently, performance characteristics of bearing system are computed.FindingsThe simulated results reveal that the location of pressurised lubricant inlets significantly affects the oil film pressure distribution and may cause a significant effect on the characteristics of bearing system. Further, the use of PVP lubricant may significantly enhances the performance of the bearing system, namely.Originality/valueThe present work examines the influence of pocket orientation with respect to loading direction on the characteristics of PVP fluid lubricated MHJB system and provides vital information regarding the design of journal bearing system.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-07-2023-0241/

Metabolic profile of follicular fluid in patients with ovarian endometriosis undergoing IVF: a pilot study

Research QuestionEndometriosis is a common benign gynaecological disorder. A number of studies have confirmed that the occurrence of disease in endometriosis patients is associated with metabolic changes in biological fluids and tissues. We set out to investigate the metabolic characteristics of follicular fluid in patients with ovarian endometriosis undergoing in vitro fertilization (IVF). DesignThe current research project is an exploratory cohort study on endometriosis. A total of 19 infertile patients with ovarian endometriosis diagnosed by laparoscopy were enrolled in this study and 23 age- and BMI-matched controls (women with infertility due to male or tubal factors). All the patients underwent IVF treatment with a gonadotropin-releasing hormone antagonist protocol and completed follicular fluid (FF) collection at oocyte retrieval. The metabolomics of FF samples was analyzed by Ultra high performance liquid chromatography-orbitrap exploris-mass spectrometer (UHPLC-OE-MS). The best combination of biomarkers was then selected by performing stepwise logistic regression analysis with backward elimination. ResultsFifteen metabolites were identified as biomarkers associated with endometriosis. A final model containing 8-hydroxy-2-deoxyguanosine, biotin, n-acetyl-L-methionine and n-methylnicotinamide was constructed. Receiver operating characteristic analysis confirmed the value of these parameters in diagnosing endometriosis, with a sensitivity of 94.7% and a specificity of 95.7%. Analysis of fortification via the Kyoto Encyclopedia of Genes and Genome showed that 15 metabolites were enriched in 8 metabolic pathways. ConclusionMetabolomics based on UHPLC-OE-MS effectively characterized the metabolomics analysis of FF in patients with ovarian endometriosis. These findings may provide a new basis for a better understanding of how diseases progress and for the discovery of new biomarkers.

An Analysis of the Carreau Fluid Pumping According to the Saffman Slip Condition Using an Asymmetric Direction by Peristaltic Pumps

Hall Effect of the peristalsis pump on a Carreau fluid is analyzed in the Saffman slip boundary conditions at the walls. Asymmetric channel is taken into consideration by wave’s propagation on the channel walls. Long wavelength and low Raynold number assumption an asymmetric into consideration for obtaining the fluid flow solution. The perturbation method is applied for solving the constructed mathematical model and the results are obtained for various characteristics of the fluid. Different graphical representations and comparisons have been examined to discuss various developments of fluid characteristics parameters of interest individually.

Influence of Suction and Injection on Peristaltic Mechanism of a Jeffrey Nanofluid in a Vertical Channel with Complete Slip Effects

The main goal of the current study is to understand how the peristaltic system of a Jeffrey nanofluid operating in a vertical tube with complete slip properties is influenced by suction and injection. The peristaltic flow was examined by several researchers using various biological fluid types. The majority of the authors used viscous (Newtonian) fluids to illustrate the peristaltic flow mechanism. Because of its uses in industry, non-Newtonian fluids have attracted a great deal of attention. There are numerous models for non-Newtonian liquids because of the complexity of fluids. The Jeffrey fluid model is the most straightforward linear model to depict the non-Newtonian fluid characteristics for which it is reasonable to expect that accurate or analytical solutions would eventually be discovered. Nanofluids are innovative substances that have endless applications in engineering, biology, medicine and other fields. This mathematical model can be used effectively to transport cervical cancer in the tiny blood channels of the cervix. The resulting flow model is then effectively simulated with the appropriate assumptions of a small Reynolds number and long wavelength. The governing conservation equations are then established. Analytical solutions have been found for, pressure rates per wavelength, temperature, velocity and concentrations of nanoparticles in the resultant flow problem. Using the software WOLFRAM MATHEMATICA, the effects of all physical parameters on streamline, velocity, temperature, concentration fields, pressure gradient, frictional force and pressure rate are graphically analyzed. We observed in both 2D-plot and 3D-plot that we increasing the slip parameters β1 and β2 lead to increase the velocity profile. By raising the Jeffrey nanofluid parameter, the pressure rise is decreased. With frictional force, the opposite behavior is observed. The effect of suction and injection parameter k on the trapping bolus, which gets greater as k is higher.

Significance of Facet Fluid Index in Anterior Cervical Degenerative Spondylolisthesis.

Retrospective cohort study. To correlate cervical facet fluid characteristics to radiographic spondylolisthesis, determine if facet fluid is associated with instability in cervical degenerative spondylolisthesis, and examine whether vertebral levels with certain facet fluid characteristics and spondylolisthesis are more likely to be operated on. The relationship between facet fluid and lumbar spondylolisthesis is well-documented; however, there is a paucity of literature investigating facet fluid in degenerative cervical spondylolisthesis. Patients diagnosed with cervical degenerative spondylolisthesis were identified from a hospital's medical records. Demographic and surgical characteristics were collected through a structured query language search and manual chart review. Radiographic measurements were made on preoperative MRIs for all vertebral levels diagnosed with spondylolisthesis and adjacent undiagnosed levels between C3 and C6. The facet fluid index was calculated by dividing the facet fluid measurement by the width of the facet. Bivariate analysis was conducted to compare facet characteristics based on radiographic spondylolisthesis and spondylolisthesis stability. We included 154 patients, for whom 149 levels were classified as having spondylolisthesis and 206 levels did not. The average facet fluid index was significantly higher in patients with spondylolisthesis (0.26±0.07 vs. 0.23±0.08, p <0.001). In addition, both fluid width and facet width were significantly larger in patients with spondylolisthesis (p <0.001 each). Cervical levels in the fusion construct demonstrated a greater facet fluid index and were more likely to have unstable spondylolisthesis than stable spondylolisthesis (p <0.001 each). Facet fluid index is associated with cervical spondylolisthesis and an increased facet size and fluid width are associated with unstable spondylolisthesis. While cervical spondylolisthesis continues to be an inconclusive finding, vertebral levels with spondylolisthesis, especially the unstable ones, were more likely to be included in the fusion procedure than those without spondylolisthesis.

Study on the Structure-Activity Relationship and Oil Displacement Characteristics of the Polysurfactant Agent.

This study examines a versatile polymer known as polysurfactant, which is synthesized by co-polymerizing flexible acrylamide and sodium acrylate hydrocarbon chain. The polymer serves as a backbone and possesses active functional groups. Notably, the polysurfactant exhibits superior plugging and flooding abilities compared to conventional polymers. The primary objective of this paper is to investigate the properties and oil displacement characteristics of the polysurfactant through indoor physical simulation experiments. The results demonstrate that the multi-branched structure of the polysurfactant enhances its ability to associate, leading to the formation of a unique spatial network structure. The inclusion of multi-branched structures notably amplifies the association effect. The critical concentration for the association is estimated to be around 800 mg/L, at which juncture the polysurfactant exhibits a viscosity retention rate surpassing 90% subsequent to shearing. Furthermore, this spatial network structure exhibits self-recovery capabilities after experiencing shear failure and displaying strong viscosity and shear resistance. In addition, the concentration of the polysurfactant can control the hydrodynamic feature size, which shows its adaptability in regulation and oil-repelling functions at reservoir permeabilities ranging from 500 to 2000 × 10-3 μm2 with resistance coefficients ranging from 108 to 320. During the microscopic oil displacement process, the polysurfactant exerts a significant impact on mobility control, while the elastic pull clearly demonstrates a commendable viscoelastic oil displacement effect. The polysurfactant exhibits a specific degree of emulsification capability towards crude oil, leading to the emulsion exhibiting typical pseudoplastic fluid characteristics. The utilization of emulsification transportation and emulsification blockage contributes to the enhancement of oil recovery. As a result, the polysurfactant exhibits multifaceted capabilities, encompassing profile control, flooding, and plugging, owing to its unique structural characteristics. Through the implementation of a field test focused on flooding in the Daqing Oilfield, a significant enhancement in the recovery rate of 10.85% is observed, accompanied by a favorable input-output ratio of 1:3.86, thereby generating significant economic advantages.

Stability analysis of nonlinear convective boundary layer flow on a shrinking surface in the presence of viscous dissipation

This study investigates analytically the stability analysis of a nonlinear convective boundary layer (BL) flow of the nanofluids GO-EG and GO-W on a shrinking surface in the presence of a magnetic field and viscous dissipation. We provide a second-order nonlinear ordinary differential equation (NODE) for temperature distribution (TD) and a third-order NODE for velocity profile (VP) coupling based on the thermophysical characteristics of the base fluid and nanofluid as well as similarity transformations (STs) in the fundamental governing equations of momentum and energy. The analytical method HAM is used to answer the equations that have been gathered. In many different industries, such as manufacturing, automotive, microelectronics, and defense, cooling of various types of equipment and devices has very important challenges. To fulfill the demands of the engineering and industrial industries, it is hoped that this issue would significantly improve the heat transformation ratio.

Effectiveness of Maxwell velocity and smoluchowski thermal slip constraints in presence of non-uniform heat source

Magnetohydrodynamic flow of nanomaterial by a stretched boundary is addressed. Entropy generation is examined. Variable fluid characteristics are considered. Buongiorno thermal enhancement model in presence of Darcy-Forchheimer expression is addressed. Nonlinear thermal radiation, non-uniform heat source and dissipation are considered in thermal expression. Slip conditions in chemically reactive flow are addressed. Here Maxwell slip velocity and Smoluchowski slip temperature are under consideration. Impact of Arrhenius activation energy is deliberated. Optimal homotopy analysis approach (OHAM) is utilized for construction of convergent solutions. Graphical description for liquid motion, entropy rate, concentration and temperature are examined. Higher magnetic variable has reverse effect on entropy rate and velocity. Higher temperature and entropy rate are seen for radiation parameter. Higher temperature dependent conductivity parameter has opposite effect on liquid motion and entropy rate. Liquid flow has same impact for both porosity and velocity slip parameters. Larger thermal slip variable lead to decrease thermal distribution while reverse impact holds for heat source. Concentration has opposite trend through both random and thermophoresis parameters. An enhancement in thermal distribution and entropy rate are seen through variable thermal conductivity. An intensification in entropy rate has been noticed through concentration dependent conductivity variable. The considered configuration has relevance for detecting cooling towers, polymer extrusion, spinning of filaments, cable coating and metallurgical processes.

DIY-PIV system for Poiseuille flow investigation in undergraduate fluid mechanics course

Fluid flow visualization techniques are becoming more widespread every year due to the availability of lasers, high-speed cameras, and the development of a large amount of image processing software. Nowadays, one of the most popular methods of flow optical visualization is particle image velocimetry (PIV). PIV is an innovative way to measure and analyze fluid characteristics, giving students a more in-depth understanding of how fluids move. This paper is focused on using low-cost components and free software to implement PIV for Poiseuille flow investigation in an undergraduate fluid mechanics course. The introduction discusses how PIV is being used as a complementary method in educational institutions, highlights the high cost of equipment to implement PIV, and gives examples of low-cost do-it-yourself (DIY)-PIV systems. The following sections present the theoretical background, descriptions of the DIY-PIV experimental setup, and plan of the investigation for the Poiseuille flow analysis. A brief overview of free image processing software for the PIV implementation is also provided. The last section presents the results of the Poiseuille flow study and analyzes the measurement quality using the created DIY-PIV system. The present experimental investigation covers topics and reinforces skills related to concepts: laminar flow, Poiseuille flow (velocity distribution, maximum and average velocity), Reynolds number, and measurement error.

Ore-forming fluid characteristics and deposit genesis of the Songjianghe gold deposit in Dunhua, Jilin Province

Ore-forming fluid characteristics and deposit genesis of the Songjianghe gold deposit in Dunhua, Jilin Province

Mason number modified for magnetorheological fluid dynamic characteristics

A quantitative analysis of characteristics of a magnetorheological fluid (MRF) under dynamic oscillation conditions was conducted using the Mason number method. The expression for the modified dynamic Mason number Mn* under different vibration frequencies, vibration amplitudes, and magnetic field strengths was established through theoretical derivations. The energy storage and loss moduli of the MRF were measured using dynamic sweep-amplitude experiments under different oscillation conditions. The results revealed that the data of the energy storage and loss moduli can be collapsed into the main curve when the dynamic Mason number Mn* is regarded as the abscissa. Furthermore, the function of each modulus and Mn* was obtained by data fitting. Thus, a unified mathematical model for MRF moduli vs. magnetic field strength and oscillatory parameters such as frequency, amplitude, et al. was established. This will provide support for the application of the MRF in vibration control and other fields.

Porous Microparticle Preparation via Tuning Electrostatic Breakup Characteristics of a Non-Newtonian Fluid for High-Performance Uranium Extraction

Porous Microparticle Preparation via Tuning Electrostatic Breakup Characteristics of a Non-Newtonian Fluid for High-Performance Uranium Extraction

Numerical Prediction of Hydrodynamic Characteristics of Wet Particles and Power-Law Fluids in a Fluidized Bed Using the Dynamic Restitution Coefficient

Numerical Prediction of Hydrodynamic Characteristics of Wet Particles and Power-Law Fluids in a Fluidized Bed Using the Dynamic Restitution Coefficient