Velocity Flow Research Articles

Flow accelerated corrosion and thinning mechanism of the pipeline after the butterfly valve based on CFD

Severe thinning was found on the pipeline after the butterfly valve of a hydrogenation unit, gravely threatening the safety and reliability of the unit. The mechanism of pipeline thinning was fully investigated in this work. The results of microstructure analysis showed that the corrosion products of thinned pipeline were mainly FeS2. The CFD results showed that flow accelerated corrosion was the main cause of pipeline thinning. The fluid behind the valve was violently disturbed due to the flow restriction of the valve disc. As a result, the pipeline suffered from erosive effect from high velocity flow with a very large wall shear stress. The region of high velocity and high wall shear stress was basically the same as the actual thinning region. The thinning mechanism of the pipeline was systematically dissected and described.

A parametric analysis of the performance of a horizontal axis tidal current turbine for improving flow-converging effect

This paper proposed a research method for secondary design and parametric analysis of the contraction section of the shroud to improve the flow-gathering effect of horizontal axis tidal current turbines. By comparing the velocity ratio, drag coefficient, and flow field stability of the nine different shroud profile types, a conclusion was drawn that the hydrodynamic performance of the exponential (Type-A) shroud is best. On this basis, the primary parametric analysis of the A profile type shroud is carried out by changing the contraction ratio of the shroud's contraction section to divide the profile into three parts. The results show that the vertical flange inhibits the flow-gathering effect of the shroud, so the secondary parametric analysis is proceeded by removing the flange and changing the flange inclination angle, respectively. At the contraction ratio of 6/8, the flow-gathering effect of each shroud is best, among which the hydrodynamic performance of Type-ABL-6-85° shroud with the flange inclination angle of 85° is best. The maximum power coefficient (Cpmax) is 43.20%, which is 31.59% higher than that with Type-A shroud when the tip speed ratio is 1.5. Therefore, it can be considered that the combined profile type of the shroud contraction section has a better flow-gathering effect than the single profile type.

Experimental and numerical study on the Izbash equation coefficients in rough single fractures

The Izbash equation has been widely used in the subsurface applications. However, the Izbash equation is still empirical, and its coefficients (scaling factor λ and power exponent M) have not been systematically characterized and quantified. In this study, laboratory experiments and numerical simulations of fluid flow across a wide range of hydraulic gradients (J = 0–4) in horizontal rough fractures were conducted to comprehensively characterize and quantify the influence of fracture geometric attributes and fluid inertial effects on λ and M. The results showed that λ increased with fracture relative roughness (RSD). The fluid inertial effect (quantified by the non-Darcy effect factor E and Re) had a two-stage influence on λ. When the fluid flow was laminar, λ increased with E. However, when the fluid flow regime starts to transition from laminar flow to turbulent flow, λ decreased with increasing E. M is positively correlated with RSD and the fluid inertia effect E. We found that the transition of flow regime from laminar to turbulent flow depended on whether the recirculation zones are fully developed. The fully developed recirculation zones determine the distortions of the velocity field and flow field, which induced the turbulent flow. The quantitative models of λ and M were obtained based on numerical simulations, which quantified the coupling influence of the fracture geometric property and fluid inertial effect. The validity of quantitative models was verified by laboratory experiments. Our work provided a new understanding of the Izbash coefficients and laid a foundation for theoretical background exploration of the Izbash equation.

Numerical Investigation of Flow Hydrodynamics in a Flow Field and Porous Substrate Configuration for Redox Flow Battery Application

In the recent past, most of the literature reported that the electrolyte circulations in parallel flow field configurations exhibit severe non-uniformity with higher Pressure Drop (Δp). The present work proposes a three-dimensional computational design of flow field configurations to achieve a single-phase uniform flow with minimal pump power and flow dispersion over an active cell area of 131cm2 for All Iron Redox Flow Battery (AIRFB). Computational investigation of the Pressure Drop (Δp), electrolyte flow velocity and uniform flow distribution in the channels and through the graphite felt electrode under various flow conditions was conducted using the Computational Fluid Dynamics (CFD) tool. It is observed from the results that the Multi-Channel Serpentine Flow Field (MCSFF) has the least pressure drop among the other flow fields. However, the Cross-Split Serpentine Flow Field (CSSFF) resulted in better flow circulation and dispersion over the entire active cell area with a high uniformity index, operating at a wide range of flow rates with a reasonable Pressure Drop (Δp). The porous media permeability and a strong function of Compression Ratio (CR) were numerically validated from the well-known correlation existing in the literature. At CR 50% it was observed that the volume uniformity index of the felt was 69%, which would correspondingly enhance the rate of mass transfer and electro-kinetics at electrode felt and ion conductivity across the membrane. The CSSFF configuration is predominant in terms of uniform flow distribution and wettability at the defined operating conditions resulting in enhanced cell performance.

Experimental study on the slamming pressure distribution of a 3D stern model entering water with pitch angles

Accurate prediction of slamming loads on stern impact is quite difficult due to complex air effects. In this paper, the load characteristics of a three-dimensional stern model with pitch angle are studied by a drop test. The pressure distribution and impact velocity at a drop of 250–900 mm and a pitch angle of 0–15° are measured. The validity of the measurement is verified based on the repeatable analysis. The load characteristics under the pitch angle are further analyzed. The pressure near the stern shaft has complex characteristics, such as multi-peak values and high-frequency oscillation. The vibration sources of pressure are clarified, where the cavity is the main, and the support frame is the secondary. In addition, the vibration characteristics of the load are also affected by the height and pitch angle, in which the drop height has a greater effect on the high-frequency components. The influence of the pitch angle on the load characteristics is further discussed. The load peak increases 30%–60% from 0° to 15°. Finally, the influence of impact velocity and three-dimensional flow on the pressure peak is discussed. These findings reveal the law of stern load affected by pitch angle.

Electro-rheological flow of seminal fluid (K-L MODEL) induced by movement of cilia in a circular conduit

The current study deals with the flow of seminal fluid through the ductus efferentes owing to electro-osmotic force and motion of cilia. The constitutive equation of semen liquid has been assumed to be described as a K-L (Kuang and Luo) fluid model. The main equations of the ciliary flow of K-L model are solved by considering the supremacy of viscous upshot over inertia influence assuming the state of long wave-length number. The analytic expressions for velocity profile, flow rate and flow impedance are derived. This is the first time to bring out to the lime light that the flow impedance is decreased and the plug core radius is enlarged with the introduction of electric force in the ciliary flow system. The effects of pertinent physiological parameters on the time-mean flow rates of rhesus monkey and human semen are thoroughly investigated. The computational mean flow rate's value over the period of time of the current mathematical model has been well matched with the corresponding experimentation values of the time-mean flow rates of rhesus monkey and humanoid semen in the path of generative and the vas deferens of the path of generative of male. Introduction of electric field into the flow ciliary system and the rheology of semen fluid described as K-L fluid model (for the values of rheological parameters of K-L fluid are considered) reduce the flow resistance, which in turn elevates the flow velocity of seminal fluid, which activates the significant and favorable changes for Oocytes getting fertilized within hours of ovulation by means of reasonable volume of semen transport into the female reproductive tract to partake a quick contact with cervical mucus and enter the cervix.

Two-phase flow in a supersonic separator for carbon capture

This work investigates a possible approach of carbon capture and two-phase flow involved. The nonequilibrium condensation, high velocity flow and shock wave in decarbonization process are described by a mathematical model. The separator is optimized through the calculations. The results show that the nonequilibrium state makes CO2 in flue gas condense spontaneously, and the system does not transfer to the equilibrium state instantly when condensation nuclei appear, but gradually turn to the equilibrium state after nucleation rate reaches the maximum. The separator with a larger separation angle is the first to condense, and the liquefied CO2 content is higher, while separator with a smaller angle produces larger droplets. Reducing the contraction ratio makes the shock wave move to the exit, and obtain higher liquid content and larger droplets. In practice, increasing the separation section length equates to a longer droplet growth time, which facilitates carbon liquefaction and separation.

Flow velocity adjustment in a channel with a floating vegetation canopy

Floating vegetation with unanchored and connected roots can completely cover the water surface of rivers, ditches, and streams. Eichhornia crassipes is a typical macrophyte with a stable network of roots that is present in aquatic environments, forming a complicated flow velocity adjustment. This study constructed model floating canopies and real E. crassipes canopies to investigate flow velocity adjustment and verify a new proposed velocity model. Laboratory experiments showed that flow velocity was modified in both the streamwise (x) and vertical (z) directions and impacted by the mean channel velocity, canopy density, and relative flow depth. The penetration distance δe of the Kelvin–Helmholtz vortices penetrating into the floating canopy increased to its maximum beyond the flow adjustment distance XD, where XD was the distance from the canopy leading edge to the position at which the flow was fully developed. The thickness of the bed boundary layer δb was related to the vegetation drag (FD(x)), the bed shear stress (τb(x)), and the height of the free-flow region below the canopy hg. New estimators for δe and δb were proposed and validated for floating canopies. Combined with the new estimators (δe and δb), flow continuity equation, momentum equation and four-layer divided method, a new analytical model was proposed to predict vertical profiles of velocity within and below a floating canopy in both the flow adjustment region (XD > x > 0) and fully developed flow region (x > XD). Fourteen groups of velocity data from this study and published literature were used to verify the proposed model. The predicted vertical profiles of velocity in flow adjustment and fully developed flow regions agreed with measurements under a wide range of vegetation and flow conditions, suggesting that the proposed model was capable of accurately predicting velocity profiles in a channel with a floating canopy. Finally, the model was validated in a channel with a real E. crassipes canopy. A comparison between predicted and measured velocities confirmed that the new model is valid for application in a channel with real floating macrophytes.

Echocardiographic functional determinants of survival in heart failure with abnormal ejection fraction.

Patients with heart failure (HF) with reduced left ventricular (LV) ejection fraction (EF) have a heterogeneous prognosis, and assessment of coronary physiology with coronary flow velocity (CFV) and coronary flow velocity reserve (CFVR) may complement established predictors based on wall motion and EF. In a prospective multicenter study design, we enrolled 1,408 HF patients (age 66 ± 12 years, 1,035 men), with EF <50%, 743 (53%) with coronary artery disease, and 665 (47%) with normal coronary arteries. Recruitment (years 2004-2022) involved 8 accredited laboratories, with inter-observer variability <10% for CFV measurement. Baseline CFV (abnormal value >31 cm/s) was obtained by pulsed-wave Doppler in mid-distal LAD. CFVR (abnormal value ≤2.0) was assessed with exercise (n = 99), dobutamine (n = 100), and vasodilator stress (dipyridamole in 1,149, adenosine in 60). Inducible myocardial ischemia was identified with wall motion score index (WMSI) stress > rest (cut-off Δ ≥ 0.12). LV contractile reserve (CR) was identified with WMSI stress < rest (cutoff Δ ≥ 0.25). Test response ranged from score 0 (EF > 30%, CFV ≥ 32 cm/s, CFVR > 2.0, LVCR present, ischemia absent) to score 5 (all steps abnormal). All-cause death was the only endpoint. Results. During a median follow-up of 990 days, 253 patients died. Independent predictors of death were EF (HR: 0.956, 95% CI: 0.943-0.968, p < 0.0001), CFV (HR: 2.407, 95% CI: 1.871-3.096, p < 0.001), CFVR (HR: 3.908, 95% CI: 2.903-5.260, p < 0.001), stress-induced ischemia (HR: 2.223, 95% CI: 1.642-3.009, p < 0.001), and LVCR (HR: 0.524, 95% CI: 0.324-.647, p = 0.008). The annual mortality rate was lowest (1.2%) in patients with a score of 0 (n = 61) and highest (31.9%) in patients with a score of 5 (n = 15, p < 0.001). High resting CFV is associated with worse survival in ischemic and nonischemic HF with reduced EF. The value is independent and additive to resting EF, CFVR, LVCR, and inducible ischemia.

Optimization of hydraulic design of approach channel of spillway by hydraulic model studies

The approach channel is intended to divert the flow safely from its original course and the diversion may be intended towards spillway, power intake or any other hydraulic structure. The hydraulic design of the approach channel involves determining cross-section dimensions of the channel for the design flood at a given flow velocity, slope and shape or alternatively determining the discharge capacity for the given layout and cross-section dimensions. Proper alignment of approach channel minimizes the head loss by reducing the oblique flows. Sometimes, the spillway approach channel is submerged with unconfined boundaries, asymmetrical in layout. However, these conditions are site-specific. Hydraulic model studies play a substantial role in testing these kinds of layouts to find out an optimum layout. Studies have been carried out on a 1:140 scale model of the spillway to optimize the layout of an unconfined, unlined, asymmetrical, and submerged approach channel by the assessment of velocity profiles and flow pattern in the approach channel for different shaped layouts. Studies indicated that the efficient layout of the approach channel is governed by its maximum available width and straightforward approach, prevention of lateral inflows by the provision of additional embankments and provision of suitable length of the guide bund.

Effects of pellet ratio on the burden movement and distribution characteristics in the BF throat

In order to solve the urgent problem of energy conservation and emission reduction in the iron and steel industry, the use of high proportion pellets in blast furnace smelting will be the trend of ironmaking development in recent years. In the present work, a geometric model of a serial-hopper bell-less type charging system based on the discrete element method was built, which was used to investigate the distribution behavior of burden under the condition of multi-ring charging and different pellet ratios. The results show: (1) the overall velocity and particle flow width of the burden at the chute outlet become larger which results the average radius of falling point increases. (2) The pellet ratio has a significant effect on the distribution characteristics and the burden profiles at the furnace throat. When the pellet ratio increases from 0% to 100%, the relative radius of peak position of the burden layer increases from 0.491 R to 0.639 R, while the peak height decreases from 0.860 m to 0.543 m. (3) The burden segregation occurs at both the radial and longitudinal positions of the layer. In the radial position, the distribution of pellets near the center is relatively concentrated compared with sinter and there is no burden segregation occurs near the relative radius of 0.590 R. In the longitudinal position, the pellets are mainly distributed at the bottom of the burden layer, while the upper part is relatively less distributed. The research content and results may give a reference for the charging operation of BF under the condition of large pellet ratio, and consequently reduce CO2 emission in ironmaking process.

Independent prognostic value of ejection fraction, resting coronary flow, coronary flow reserve, myocardial viability, and inducible ischemia in heart failure with a reduced ejection fraction

Abstract Background and Aims Patients with heart failure (HF) with reduced left ventricular (LV) ejection fraction (EF) have a heterogeneous prognosis, and assessment of coronary physiology with coronary flow velocity (CFV) and coronary flow velocity reserve (CFVR) may complement established predictors based on wall motion. Methods and results In a prospective multicenter study design, we enrolled 1,408 HF patients (age 66±12 years, 1,035 men), with EF &amp;lt;50%, 743 (53%) with coronary artery disease, and 665 (47%) with normal coronary arteries. Recruitment (years 2004-2022) involved 8 accredited laboratories, with inter-observer variability &amp;lt;10% for CFV measurement. Baseline CFV (abnormal value &amp;gt;31 cm/s) was obtained by pulsed-wave Doppler in mid-distal LAD. Coronary flow velocity reserve (CFVR, abnormal value ≤2.0) was assessed with exercise (n=99), dobutamine (n=100), and vasodilator stress (dipyridamole in 1,149, adenosine in 60). Inducible myocardial ischemia was identified with wall motion score index (WMSI) stress&amp;gt; rest (cut-off ∆≥0.12). LV contractile reserve (CR) was identified with WMSI stress&amp;lt; rest (cutoff ∆≥0.25). Test response ranged from score 0 (EF&amp;gt;30%, CFV ≤31 cm/s, CFVR &amp;gt;2.0, LVCR present, ischemia absent) to score 5 (all steps abnormal). All-cause death was the only end-point. Results During a median follow-up of 990 days, 253 patients died. Independent predictors of death were EF (HR: 0.956, 95% CI: 0.943-0.968, p&amp;lt;0.0001), CFV (HR: 2.407, 95% CI: 1.871-3.096, p&amp;lt;0.001), CFVR (HR: 3.908, 95% CI: 2.903-5.260, p&amp;lt;0.001), stress-induced ischemia (HR: 2.223, 95% CI: 1.642-3.009, p&amp;lt;0.001), and LVCR (HR: 0.524, 95% CI: 0.324-.647, p=0.008). The annual mortality rate was lowest (1.2%) in patients with a score of 0 (n=61) and highest (31.9%) in patients with a score of 5 (n=15, p&amp;lt;0.001). Conclusion High resting CFV predicts worse survival in ischemic and nonischemic HF with reduced EF. The value is independent and additive to resting EF, CFVR, LVCR, and inducible ischemia.

Investigating Particle Paths in Intracranial Aneurysms: A Parametric Study

A large part of computational fluid dynamics (CFD) studies in hemodynamics concentrates on the berry-like bulgings on cerebral vessel walls, called intracranial aneurysms (IA). One technique is the calculation of particle paths, which can help understand important physiological processes like thrombus formation or drug propagation. The problem is that the particle paths can display chaotic nature even in simple flows, thus, investigating the effects of parameters on the particle paths is essential. The method used in this study consists of four steps. The first step is to voxelize the observed domain into a uniform voxel grid, the second step is to simulate the velocity flow field using the lattice-Boltzmann method, then to calculate one million particle paths using a fourth-order Runge-Kutta integrator. Lastly, the final step is the calculation of the relative perimeter, relative area and their ratio (P/A ratio) for each outlet when the particle release plane is colored according to the outlets the particles took. Five patient-specific cases were investigated. After a voxel size and integrator time step dependence study, the effect of the presence of the aneurysm sack and the particle release time within the heart cycle were assessed. Based on five geometries, the presence of the aneurysm sac increases the P/A ratio (which is a direct link to the chaotic nature of the particle paths), and when the particles are released near the peak and the decelerating phase of the heart cycle, the P/A ratio also significantly increases.

Abstract 197: Establishing a Novel Pulse Wave Velocity-Guided Mouse Model of Cardiac Arrest With Different Durations

Background: Neurological and cardiovascular injuries are the leading causes of death following cardiac arrest (CA). Few rodent models recapitulate these post-resuscitation symptoms. Aims: To develop extended ischemic CA models under Pulse Wave Velocity ( PWV) guidance with consistent post-CA brain injury (PCABI) and coronary dysfunction as potential therapeutic targets and mechanical studies. Methods: Forty-eight mice were randomized into four experimental groups (control, 8-, 12-, and 16-min CA). Potassium chloride (KCL) was intravenously injected, resulting in immediate asystole. Mice were resuscitated with an injection of epinephrine and manual chest compressions. PWV was monitored for the left carotid artery velocity and coronary flow reserve (CFR). Resuscitability, synaptic density in the hippocampal CA1 region, blood-brain barrier (BBB), and neurologic deficit scores (NDS) were also evaluated. Results: The PWV could monitor rapid asystole after KCL injection, improve cardiopulmonary resuscitation (CPR) success rates, and avoid the pre-matured end of resuscitation. Compared to the standard control, mice with 8-min CA had preserved CFR, mild loss of synaptic density (p&gt;0.05), mild hypothermal, and a normal electrocardiogram. They maintained BBB integrity with no significant change to neurologic function. Compared with a 92% CPR success rate in 8 min-CA mice, 12 min-CA mice had 83%, and 16 min-CA mice had 58% resuscitability. Twelve min-CA mice had significantly impaired CFR at 24 hours and high lethality (40%, P&lt;0.05) within the first three days; 16 min-CA mice worsened (33% survival rate, p&lt;0.01). The 24 hrs electron microscope showed that CA-induced synaptic vesicle densities were ischemic time-dependent [350±60 (control) vs. 289±64 (8 min CA) vs. 269±34 (12 min CA) vs. 181±41/field (16 min CA)], consistent with NDS. The cerebrum and hippocampus were the most valuable regions, indicated by Evans blue evaluation at 48 hrs after CA. Conclusions: We established elongated PWV-guided CA models as with successful CPR, post-CA neurological deficits, leaky BBB, loss of synaptic density, coronary endothelial dysfunction, and even death in mice, which closely recapitulated the post-resuscitation symptoms in survived patients after CPR.

Abstract 12854: Early and Late Features of Intracardiac Flow in Repaired Tetralogy of Fallot (rTOF) Patients Using Doppler Velocity Reconstruction (DoVeR)

Background: Intracardiac flow analysis has implicated flow energy loss (FEL), kinetic energy (KE) and vortex strength (VS) as markers of ventricular dysfunction in repaired Tetralogy of Fallot (TOF); no studies have investigated early vs. late intracardiac flow conditions after repair. We utilized novel echocardiography (echo) based Doppler Velocity Reconstruction (DoVeR) to determine FEL, KE and VS in pre-operative TOF vs early post-repair (&lt;1 month) and late post-repair (&gt;10 years). Methods: This was a single-center retrospective cross-sectional study on TOF patients with pre- and post-operative surveillance transthoracic echo. Apical 4 chamber color Doppler views were collected. The streamfunction-vorticity formulation was used to reconstruct left ventricular (LV) blood velocity fields by DoVeR. Velocity flow fields were evaluated for peak FEL, KE and VS. The FEL was also normalized against KE to account for physiologic variations. Data were compared via one-way ANOVA. Results: Echo studies from 14 pre-operative (1.7±0.5 months), 14 early-post repair (3.6±2.3 months) and 15 late-post repair (16.5±6.6 years) TOF patients were included. There was significant variation in FEL, KE, VS, and normalized FEL across timepoints (all p&lt;0.05) (Figure B). In general, when compared to pre-operative TOF, the early post-repair cohort had lower FEL/KE/VS corresponding to reduction in ventricular volume load; however late post-repair cohort had higher FEL/KE/VS, suggestive of effects from long-term interventricular interactions. Conclusion: The LV intracardiac flow in TOF changes early after initial repair and late after repair. DoVeR could potentially be used to serially evaluate TOF patients.

Numerical investigation on the effect of flexible vegetation in open-channel flow incorporating FSI

ABSTRACT The understanding and studying of the vegetation effect on the natural water flows is an important objective in modern scientific research regarding river management and restoration, with high environmental impact. Vegetation in the open-channel flow significantly affects the velocity of flow. In the present study, influence of the flexible vegetation on the flow characteristics of open-channel flow was resolved numerically using computational fluid dynamics. For the numerical study of the open-channel flow with flexible vegetation, fluid–structure interaction (FSI) is used. The obtained results were then compared with the numerical results of rigid vegetation. The influence of different parameters such as depth of flow, flow velocity, slenderness ratio of vegetation and density of vegetation were studied. It was found that incorporation of FSI in the analysis is essential to accurately predict the flow characteristics. It was also found that the simulation using FSI is more critical in case of submerged vegetation in an open-channel flow for all flow velocities.

A CPC fractional model of the heat and mass transport mechanism in Carbon nanotubes with slip effects on velocity

A fractional technique is used to evaluate the temperature, mass, and velocity flow of single and double wall CNTs over a vertical plate. Slip boundary conditions and applied magnetic force are addressed. Human blood is used to examine how base fluid behaves. Applying the proper dimensionless variables results in the dimensionless formulation of initial and boundary conditions related to the governed dimensional concentration, momentum, and energy equations. The Laplace transform technique is used to resolve the dimensionless governing partial differential equations and get the solutions. The constant proportional Caputo (CPC) time-fractional derivative is a unique class of fractional model used in the simulation technique. The fundamental definitions are used to support the said model first. Using MWCNTs and SWCNTs in comparison to the flow characteristics, a thermal and mass study is given. The heat and mass transfer processes for single-walled carbon nanotubes (SWCNTs) have been shown to typically be progressive. The momentum profile decreases as the fractional variables rise. Multi-walled carbon nanotubes (MWCNTs) show more progressive velocity control as a result of the magnetic parameter. Graphs demonstrate the influence of embedding factors on the velocity, energy, and concentration profiles.

A data-driven model to determine the infiltration characteristics of air curtains at building entrances

The air curtain reduces heat exchange between the two sides by creating a virtual partition and works as a solution for improving building sealing and energy efficiency. Currently, the analytical numerical coupling method has achieved some success in describing the low-order theoretical descriptions of air curtain flow, but its application scope is limited. This paper introduces a data-driven model (DDM) to predict the operation state of the air curtain and the volume flow rate through the entrance. A computational fluid dynamics model is built to generate the dataset, which is validated by comparing velocity and volume flow rate with the published data in the literature. Three of the widely used algorithms are tested: support vector machine, random forest, and backpropagation neural network (BPNN). The main conclusions are as follows: (1) The combination of pressure difference and air supply velocity can quickly determine the operation state of the air curtain in the scene (f1-score = 0.9). (2) A single hidden layer BPNN can achieve high-precision prediction of volume flow rate (R2 = 0.92). (3) Compared to theoretical methods, the DDM can retain three-dimensional characteristics of the jet and capture additional details. The approach proposed in this paper can be applied to practical environments to rapidly and accurately optimize the operating parameters of air curtains.

Numerical Investigation of Immersion Cooling Performance for Lithium-ion Polymer (LiPo) Battery: Effects of Dielectric Fluids and Flow Velocity

This study investigates the enhancement of immersion cooling performance for a single 14.6 Ah lithium-ion polymer (LiPo) battery cell by using air, palm oil, and engineered fluid (3M Novec 7000) as dielectric fluids. The research aims to observe the temperature distribution and rate of heat transfer on the battery cell at a 3C discharge rate, while varying the fluid velocity flow (0 mm/s, 1 mm/s, and 50 mm/s) and fluid types. Computational fluid dynamics (CFD) simulations were performed using ANSYS Fluent software, with heat generation from the LiPo battery simulated using the Newman, Tiedmann, Gu, and Kim (NTGK) semi-empirical electrochemical model. Results revealed that palm oil demonstrated the optimum cooling effect, reducing peak temperature to safe operating temperature region by 62.4% within 1020 seconds. Fluid flow velocity strongly influenced temperature distribution and heat transfer rates, with 50 mm/s resulting in a more uniform temperature distribution compared to 1 mm/s and 0 mm/s. The rate of heat transfer was highest at 1 mm/s and intermediate at 50 mm/s. Considering the abundance of palm oil in Malaysia, utilizing it as the dielectric fluid with a 50 mm/s flow velocity yields the best cooling effect for the 14.6 Ah LiPo battery at a 3C discharge rate.

Bioconvection Flow in the Presence of Casson Nanoparticles on a Stretching/Shrinking Vertical Sheet with Chemical Reaction

A Casson nanoparticle is used in this study to investigate the effects of toxic reactions, temperatures, and concentrations on convective heat transfer flow across a stretching/shrinking vertical sheet. The goal is to convert the control linear partial differential equations (PDEs) into an ordinary differential equations (ODEs) set and analyses them statistically using the Bvp4c technique in MATLAB software. It is necessary to look how various variables, such as the Casson nanofluid measurement, the chemical change constants and Prandtl numbers, the concentration-thermal-buoyancy ratio, the microorganism-to-thermal-buoyancy rate of return, the Lewis number, and other bioconvection-related parameters (such as the variation in micro-organism concentration and the buoyancy parameter), affect each other. The numerical results of the velocity, temperature, concentration, and bioconvection flow profiles are displayed.