Optimal Flow Pattern Research Articles

Experimental and numerical investigations of liquid cooling plates for pouch lithium-ion batteries considering non-uniform heat generation

Ensuring the thermal safety of lithium-ion batteries requires efficient and reliable thermal management systems. However, the non-uniform heat generation of lithium-ion batteries results in uneven temperature distribution, which complicates the comprehension of the flow pattern design and operating parameter optimization in liquid-based battery thermal management, especially under extreme conditions. This study evaluates the thermal management performance of four classic liquid cooling plate designs for pouch batteries by considering their non-uniform heat generation through the electrochemical-thermal coupled model. Through experiment and numerical simulation, the optimal flow pattern is identified. Subsequently, the capability of the thermal management system, utilizing the best flow design, is further assessed under varying operating conditions. The results indicate that while a higher flow rate marginally enhances cooling, the coolant inlet temperature exerts a more substantial impact on the cooling performance. In addition, the recommended parameter settings for cell-level liquid cooling systems are outlined under extreme conditions. With a 5 C discharge rate and an initial temperature of 35 °C, the recommended coolant temperature range and coolant flow rate range are 20–30 °C and 60–100 mL min−1, respectively. As a typical example of computer-aided engineering, this study reveals the impact of battery non-uniform heat generation on battery temperature performance and provides a critical reference for the optimization of liquid-based battery thermal management systems.

How caged motion in the contact layer enhances thermal tunneling across a liquid/solid interface

Ever more powerful and densely packed chips for applications like cryptocurrency mining and artificial intelligence generate such enormous heat fluxes that designers are pivoting from gas to liquid cooling to forestall damage from thermal runaway. Even with optimal flow patterns, however, the intrinsic thermal boundary resistance at the liquid/solid (L/S) interface poses an additional source of thermal impedance. There is a lingering misconception in the field that the higher the liquid contact density, the more frequent the L/S collision rate and the smaller the thermal slip length. Here we present an insightful counterexample based on nonequilibrium molecular dynamics simulations of a simple liquid confined between two face centered cubic crystals at different temperatures aligned with the [001], [011] or [111] facet plane. Measurements of various static and dynamic quantities of the contact layer reveal the ways in which long-range order, anisotropy of the L/S potential, and correlated motion act to reduce thermal boundary resistance. Systems with the smallest thermal slip length exhibit two distinct features: 2D caged motion with stringlike alignment of liquid particles, unlike that observed in glassy systems, and larger nonergodicity parameter with shorter, not longer, caging times. This trapping and release mechanism suggests a paradigm for the design of L/S interfaces to maximize thermal exchange across a classical L/S interface. Published by the American Physical Society 2024

Adaptive control of transportation infrastructure in an urban environment using a real-coded genetic algorithm

The management of urban areas requires the development of an effective strategy for the evolution of transportation infrastructure to ensure the smooth flow of traffic and pedestrians. A crucial component of this infrastructure is the traffic light system, which plays a vital role in traffic control and traffic safety. Improving the efficiency of traffic control systems in intelligent transportation systems (ITS) has a significant impact on a city’s economy. As a result, the cost of fuel for road users can be reduced, and their level of social comfort can be improved, among other benefits. This paper proposes a novel approach to optimizing traffic flows in smart cities, based on the combined use of the genetic optimization algorithm and the ITS simulation model we developed. The proposed method aims to enhance the efficiency of existing traffic control systems and achieve optimal traffic flow patterns, thereby contributing to a more sustainable and efficient urban environment. The optimization algorithm shown here aggregates the objective functions using a simulation model of a real region of the Moscow road network. The model includes intersections, pedestrian crossings and other features that are implemented in the AnyLogic system. The research aims to create a decision-support system for managing urban transport infrastructure. This system will be used to optimize the duration of traffic light phases in order to minimize the time vehicles spend passing through key nodes in the urban road network. It will also optimize pedestrian flow, reducing the impact of traffic on the environment and improving fuel efficiency. By applying this approach, the capacity of the street network can be significantly increased. Additionally, the negative effects of traffic flow on the environment can be reduced by optimizing fuel use and reducing waiting times at intersections managed by traffic lights. The research methodology involves the development of a hybrid evolutionary search algorithm, the creation of a simulation model for transportation and pedestrian flows in the AnyLogic and a series of optimization experiments that demonstrate the effectiveness of the proposed approach when applied to the modeling of complex urban transportation systems.

Optimal flow pattern around hybrid groins with various orientations to improve fish habitat via Experimental Investigation using Acoustic Doppler Velocimeter

Optimal flow pattern around hybrid groins with various orientations to improve fish habitat via Experimental Investigation using Acoustic Doppler Velocimeter

Arrangement optimization of spherical dimples inside tubes based on machine learning for realizing the optimal flow pattern

Arrangement optimization of spherical dimples inside tubes based on machine learning for realizing the optimal flow pattern

An optimization method for enhancement of gas–liquid mass transfer in a bubble column reactor based on the entropy generation extremum principle

In this study, an optimization method is proposed to enhance the gas–liquid mass transfer in bubble column reactor based on the entropy generation extremum principle. The mass transfer- induced entropy generation can be maximized with the increase of mass transfer rate, based on which the velocity field can be optimized. The oxygen gas–liquid mass transfer is the major rate-limiting step of the toluene emissions biodegradation process in bubble column reactor, so the entropy generation due to oxygen mass transfer is used as the objective function, and the conservation equations of the gas–liquid flow and species concentration are taken as constraints. This optimization problem is solved by the calculus of variations, the optimal liquid flow pattern is obtained and the relationship of the maximum mass transfer enhancement on viscous dissipation is revealed, which can be used to improve the design of internal structure of the bubble column reactor.

The Covered Endovascular Reconstruction of the Aortic Bifurcation (CERAB) Technique for Aorto-Iliac Occlusive Disease.

Endovascular treatment options of aorto-iliac occlusive disease have emerged, leading to better outcomes in more complex pathology, which typically involves a reconstruction of the aortic bifurcation. The Covered Endovascular Reconstruction of Aortic Bifurcation (CERAB) configuration was introduced in 2013, in an attempt to optimize outcomes, when compared to the kissing stent configuration, which was traditionally the preferred endovascular technique for this pathology. CERAB aims to optimize geometry, and with that the arterial flow patterns that are associated with loss of patency. In CERAB, the aortic bifurcation is reconstructed using three balloon-expandable covered stents in a tight connection with each other and with an appropriate wall apposition, thereby minimizing geometrical mismatch (Fig. 1a-c). The reconstruction can be extended on both sides and could be combined with chimney, or parallel, grafts in aortic side branches that need to be preserved. In the current paper, the details of the CERAB technique are described and supported by evidence derived from pre-clinical studies that confirm the more optimal geometry and flow patterns compared to kissing stents. Also, a summary is provided of published clinical evidence, including technical and clinical outcomes of the technique. These data show promising early results, with patency rates in line with those achieved with open surgery, also in patients with extensive disease. Finally, the potential modes of failures and future developments are discussed.

Optimal Inhalation Flow Pattern from Turbuhaler Predicted by Laser Photometry.

Background: The emitted dose (ED) from most dry powder inhalers (DPIs) is almost independent of peak inspiratory flow (PIF) above a certain value, which is specific to the individual DPI. However, the ED of the Turbuhaler® (TBH) increases linearly with PIF increments. This study investigated the powder clearance and clinical utility of TBH performance features by using the photo-reflection method (PRM), a type of laser photometry. Methods: Pulmicort® (PLM) (containing budesonide only) and Symbicort® (SMB) (drugs with lactose particles) were inspired with a ramp-up pattern of several PIF intensities using a vacuum pump. Time trajectories of particle release and PIF were then compared. Results: The particle-release trajectories from both types of DPIs were similar, consisting of a sharp increment phase (∼0.15 seconds) followed by exponential decay. Both onset to the peak of particle-release time and particle-release times were not affected by PIF changes when the PIF was >40 L/min. EDs from both TBHs were linearly related to PIFs, and the slope of the regression equation for SMB was 2.4-fold larger than that of PLM. The peak of the released particles (PKIED) was also linearly related to PIF. A linear relationship was also observed between ED and PKIED in both TBHs, and these regression lines overlapped. Conclusion: EDs from the TBH were dependent on PKIED. Therefore, rapid, initially strong, and deep inhalation should be advised while using the TBH. PRM could measure the fine and small amount of particles released from the TBH.

Contrast flow patterns based on needle tip position during cervical transforaminal epidural injections.

Few studies have evaluated the effect of final needle position on contrast flow patterns during the performance of cervical transforaminal epidural steroid injections (TFESIs). To analyze fluoroscopically guided cervical TFESI contrast flow patterns based upon final needle tip position. Retrospective, observational in vivo study. Outpatient private practice physical medicine and rehabilitation spine clinic. One hundred consecutive patients undergoing cervical TFESIs. Cervical TFESIs. Categories of contrast flow patterns including epidural, intraforaminal, "sufficient to inject," and "predominantly epidural and/or intraforaminal," based upon final needle tip position. Two independent observers reviewed images from 100 consecutive patients and classified injectate flow patterns stratified by needle tip position. The interrater reliability for all categories of interest was moderate, with kappa values from 0.61 to 0.76. More medially placed needles (middle third and lateral third of the articular pillars) resulted in higher rates of epidural contrast flow (75%; 95% confidence interval [CI]: 56%-94%; and 60%; 95% CI: 47%-73%) compared to needles placed lateral to the articular pillars (26%; 95% CI: 8%-44%), and higher rates of "predominantly epidural and/or intraforaminal" flow patterns with needles placed in the middle one third (75%; 95% CI: 56%-94%) and lateral one third of the articular pillars (47%; 95% CI: 34%-60%) compared to flow patterns when needles were placed lateral to the articular pillars (17%; 95% CI: 2%-32%). No needles were placed in the medial third of the articular pillars. More medially placed needle tips result in more optimal flow patterns during cervical TFESIs. The importance of this finding is unknown as clinical outcomes were not measured.

A global optimum flow pattern for feeder reconfiguration to minimize power losses of unbalanced distribution systems

The loss minimization has been an important optimization problem in distribution systems because of the economic incentives. The state-of-the-art feeder reconfiguration for minimizing unbalanced distribution systems’ losses cannot prove the optimality of solutions mathematically due to the non-convexity of the problem. This paper proposes a global optimal flow pattern of feeder reconfiguration to provide a best start point and convergence direction for search strategies. The global optimality and the uniqueness of the global optimal flow pattern are proved. Therefore, the loss of the global optimal flow pattern is the lower bound of the feeder reconfiguration for loss minimization. Two global optimal flow pattern-based search strategies are developed to find the global or near optimal solutions. The performance of the proposed algorithms is validated with three test systems for different application scenarios. Test results demonstrate that the efficiency of the search strategies is greatly improved by the global optimal flow pattern and the optimality of solutions can be verified.

Optimal manure utilization chain for distributed animal farms: Model development and a case study from Hangzhou, China

Manure management is a concern for many livestock and poultry producers all around the world. Manure is generated, processed, transported, and utilized in various ways. Manure management requires the coordination of animal feeding operations (AFOs), centralized processing facilities (CPFs), and crop farms. Such a manure utilization chain is more than an individual farm scale, and it is a complex nexus between different production systems. In this study, the manure utilization chain, which recognizes manure management behaviors at different units of a region, was proposed to ensure sustainable manure utilization for distributed animal farms. The goal of this study was to develop a regional manure utilization chain (RMUC) model to minimize annual manure utilization costs by identifying the optimal manure flow patterns among AFOs, CPFs, and crop farms. The model was implemented to evaluate the manure utilization chain in Hangzhou, China. The results showed that the average solid manure logistics cost was CNY 20/ton (1 CNY ~ 0.14 USD), and the average slurry manure utilization cost was CNY 25.4/ton when the manure nutrients were adequately distributed. If the solid manure processing capacities of CPF were optimized, the average solid manure logistics cost would be reduced to CNY 8/ton. This paper also discusses the cost of executing the manure land application setbacks (the minimum distance required between manure application areas and sensitive areas). If Hangzhou followed manure land application restrictions of Illinois, U. S, the slurry manure utilization cost (CNY 65.8/ton) would be 2.59 times greater than the cost (CNY 25.4/ton) in the current scenario. Manure management would be more similar to other waste management and rely on centralized strategy instead of individual farm management.

Determining Satisfaction from Gameplay by Discussing Flow States Related to Relaxation and Excitement

Currently, people use the Internet for both work and leisure. The hedonic features of a website are as crucial as its functional features. In recent years, website researches have begun paying attention to user experience because people immerse games on websites. This study examined how satisfaction differs in different flow states. This study investigated the flow experience of online game players in states of excitement and relaxation and explored how flow states influence website satisfaction and actual use time. Because motivations engendered by goal or behavior orientation moderates the relationship between flow states and website satisfaction, the optimal flow pattern may differ between goal- and behavior-oriented website game players. This study used clustering analysis and a t test to divide and compare the groups. The total number of respondents was 340. Among these, 175 players (51.47%) were male. The results revealed that the goal-oriented players were more satisfied in the relaxation flow state, and the behavior-oriented players were substantially satisfied at an exciting flow experience. However, both goal- and behavior-oriented players demonstrated no significant difference in the time spent on playing games when they were immersed in a flow state. From a theoretical perspective, this study demonstrated that different balances between challenge and skill result in different experiences and satisfaction levels. This study provided a novel finding that the spending time playing games did not mean that the players were more satisfied. Game developers should thoroughly evaluate the balance between challenges and skills based on their target players and company strategies when designing games.

Conjugate heat transfer enhancement in the mini-channel heat sink by realizing the optimized flow pattern

Mini-channel heat sinks are popular in cooling high heat flux devices due to the high convective heat transfer performance associated with moderate pressure drop penalty. It is of great significance to further improve the thermal hydraulic performance in the mini-channel heat sink so as to adapt it to higher heat flux conditions. In this paper, a new method of realizing the optimized flow field to enhance the thermal hydraulic performance was carried out successfully in the mini-channel heat sink. The chosen mini-channel heat sink was 30 mm × 30 mm in substrate size with Reynolds number ranging from 100 to 1100. Through conjugate heat transfer optimization based on exergy destruction minimization principle, the optimized flow pattern was characterized by three pairs of longitudinal swirls flow. Subsequently, the inclined parallelepiped ribs were proposed to realize the optimized flow pattern in the mini-channel heat sink. The heat transfer enhancement mechanism was investigated by analyzing velocity distributions, temperature distributions, and heat convection intensity. Besides, the total thermal resistance was decreased and the exergy destruction minimization principle was verified. As a result, the variation ranges of Nu/Nu0, f/f0, efficiency evaluation criterion (EEC), and overall performance criterion (R3) were 1.35–5.92, 1.27–8.75, 0.68–1.12, and 1.31–4.22, respectively. The maximum average heat flux could achieve 3.2 × 106 W/m2 within a temperature difference of 60 K between substrate and fluid. The configured parameters pitch ratio (PR) and width ratio (WR) were recommended as 1 and 0.2, respectively. This work is conducive to the structural design of mini-channel heat sinks.

Experimental investigation of the coherent structures in a spirally corrugated pipe

Previous numerical and theoretical results (Chen et al., 2019; Liu et al., 2018; Zhao et al., 2019) based on the optimization theory of convective heat transfer reveal that the optimized flow structures in a straight circular pipe enhancing convective heat transfer are multiple longitudinal vortices. This conclusion encourages us to find out whether such flow structures really exist in some enhanced heat transfer pipes by means of advanced experimental techniques. Therefore, a typical enhanced heat transfer pipe was selected, namely a spirally corrugated pipe, and stereoscopic particle image velocimetry (SPIV) was employed to measure its internal instantaneous flow field. Moreover, the proper orthogonal decomposition (POD) method was used to extract the large-scale coherent structures from the measured instantaneous velocity fields. Besides the spirally corrugated pipe, the fully developed turbulent flow in a straight pipe was also analyzed as benchmark of the enhanced heat transfer pipes. The results reveal that longitudinal whirling flow with multi-vortices is formed in both the fully developed turbulent flow field of the straight pipe and the spirally corrugated one. It is thus easy to explain the heat transfer enhancement mechanism of the above flow structures from the perspective of momentum transfer. The flow structures of the fully developed turbulent flow in a straight pipe are quite similar to the optimal flow pattern from the optimization theory. More specifically, multiple longitudinal vortices are spontaneously generated due to turbulence without external heat transfer enhancement techniques. Furthermore, the flow structures similar to multiple longitudinal vortices also exist in the spirally corrugated pipe, although these flow structures deviate from symmetric multiple vortices. Moreover, the flow structures in the spirally corrugated pipe are much more energetic than those in the fully developed turbulent flow in a straight pipe. This is probably the reason why a spirally corrugated pipe can enhance heat transfer compared with a straight circular pipe.

Ordinal optimisation approach for complex distribution network reconfiguration

The increasing complexity of the distribution system makes the practical distribution network operation much difficult. This paper presents an ordinal optimisation (OO) approach to solve the distribution network reconfiguration, which is an NP- hard problem with discrete control variables. OO uses crude and computationally fast model to reduce the search space. The spirit of OO is to seek the good enough solution instead of the best with high probability. The proposed approach is validated with two practical distribution systems, TPC 84 node test system. The results are compared with Optimal Flow Pattern (OFP), Common Genetic Algorithm (CGA), Partheno Genetic Algorithm with Tree Structure Encoding technology (TSE-PGA) and Second-Order Cone Programming (SOCP).

Performance of continuous helical baffled heat exchanger with varying elliptical tube layouts

Helical flow is an optimal flow pattern in shell-and-tube heat exchangers, but the poor heat transfer performance has been always the bottleneck. Aiming to improve heat transfer without tremendous increase of pressure drop, the optimized continuous helical baffled heat exchangers with varying elliptical tube layouts are proposed and investigated by numerical simulation. It concludes that the tube-array angle influences the characteristics of flow and heat transfer significantly. The optimized tube layout can improve heat transfer in fully-developed section and decrease vortices at the back of tubes to some extent. The mean convective heat transfer coefficient and the pressure drop are respectively 2.10–2.33 times and 1.82–4.46 times higher than that of the original heat exchanger with concentric annular layout, and the comprehensive performance proves to be improved by about 50%. The results show that the optimized elliptical tube layouts with varying tube-array angles can realize the initial objective, especially when the Re number of flow is relatively small. This research is beneficial for further optimization on helical baffled heat exchangers to improve heat transfer as well as comprehensive performance.

Modeling the Equilibrium Road Network Capacity

The aims of this paper are to present a new model to calculate the maximum equilibrium road network capacity and obtain the associated optimal origin-destination (i.e. OD) flow pattern for a general road network with given network topology and link attributes. First, the Static Congested Traffic Assignment (SCTA) is introduced to describe the network where all used routes are in a congested state. Congested Equilibrium Travel Times (CETTs) between OD pairs obtained by the SCTA model are regarded as the corresponding upper limits of actual equilibrium travel times which are called Uncongested Equilibrium Travel Times (UETTs) and derived from the traditional Static Uncongested Traffic Assignment (SUTA) model. The main idea of modeling is that the total OD flows can be maximized by flexibly scaling and adjusting OD flows of each individual OD pairs to make the UETTs of all OD pairs reach their upper limits (i.e. CETTs). Next, a novel equilibrium road network capacity model is built by combining the SUTA and the SCTA models. Then, the equivalency condition and the solution uniqueness of the proposed model are proved. The paper moves on to provide two solution algorithms together with an analysis of the model characteristics. Finally, through three numerical examples, it is demonstrated that the proposed model can obtain the unique equilibrium network capacity with the given network topology and associated link attributes. The optimal OD flow pattern, which leads to the maximum total OD flows, is thus obtained. The findings in the paper can help to improve the utilization of road networks and contribute to land development planning and control.

Optimal official work start times in activity-based bottleneck models with staggered work hours

ABSTRACTThis paper aims to optimize official work start times (OWSTs) in activity-based bottleneck models with staggered work hours (SWH). In the models, commuters’ departure time choice from home to work is assumed to follow user equilibrium principle in terms of total activity utility. An activity-based bottleneck model with a single OWST is firstly considered. According to the equilibrium flow pattern, the optimal single OWST is analytically derived with maximized total system activity utility (TSAU). Then, we find that there exist four possible equilibrium traffic flow patterns for the bottleneck model with double OWSTs. The optimal equilibrium traffic flow pattern and the optimal OWSTs with maximal TSAU are also derived. Besides, the optimal SWH scheme for the bottleneck model with double OWSTs is extended to the situation of the bottleneck model with multiple OWSTs. Finally, numerical examples are developed to illustrate the properties of the proposed models.

Large allowance electrochemical turning of revolving parts using a universal cylindrical electrode

There are many large-scale revolving parts in aerospace engines, which usually require relatively large machining allowances to ensure production of the necessary shapes and sizes. Efficient removal of the machining allowances from such large-scale revolving parts, especially for hard-to-cut materials, represents a challenge for traditional mechanical processing. In this research, electrochemical turning with a universal cylindrical electrode is proposed as an efficient method to remove the large machining allowance of revolving parts. Lateral flow and internal flow patterns are exploited to ensure timely removal of electrolysis products and Joule heat. The electric field distribution shows that the current in the machining area increases significantly for the method. The flow field distribution shows that a more uniform flow velocity distribution can be obtained using an internal flow pattern. Experiments were performed to verify the proposed method. The results show that the internal flow pattern allows for faster feed rates and more stable processing, and the material removal rate may be improved significantly through use of an optimized flow pattern, especially for work-pieces with a large machining allowance. To demonstrate application, three differently shaped revolving structures were machined successfully with a radial removal allowance of 10 mm.

InVitro Evaluation of Optimal Inhalation Flow Patterns for Commercial Dry Powder Inhalers and Pressurized Metered Dose Inhalers With Human Inhalation Flow Pattern Simulator

This study aimed at developing a novel analytical method to identify optimal inhalation flow patterns for commercial dry powder inhalers (DPIs) and pressurized metered dose inhalers (pMDIs). As typical commercial DPI and pMDI, Pulmicort® Turbuhaler®, and Sultanol® Inhaler were evaluated by an in vitro inhalation performance testing system with a flow pattern simulator. An 8-stage Andersen cascade impactor (ACI) or twin stage liquid impinger (TSLI) was applied to determine the inhalation performance. The peak flow rate (PFR) of the inhalation flow pattern was set from 15 to 80 L/min in reference to our previous study. From TSLI test results, a higher PFR improved the inhalation performance of the DPI, while the performance of the pMDI was less affected by the PFR. Conversely, from ACI test results, the pMDI performance decreased with a higher PFR, while the DPI followed a similar pattern as in the TSLI test results, because ACI is a finer aerodynamic classification apparatus than TSLI. These results suggested that our in vitro system using a human inhalation flow pattern simulator successfully detected different optimal inhalation patterns between DPI and pMDI. That is, the higher PFR is better for Pulmicort® Turbuhaler® (DPI). Conversely, lower PFR is desirable for Sultanol® Inhaler (pMDI).