Obstruction Factor Research Articles

Impact of upstream buildings on Wind-Driven Rain Loading: Refining Obstruction Factor in ISO semi-empirical model based on CFD

CFD is a valuable tool for assessing Wind-Driven Rain (WDR) loading, one of the most important environmental loads for façade design. The majority of previous studies on this topic have primarily concentrated on simple building configurations, i.e., stand-alone buildings. Hence, prior findings may not be applicable to consider the impact of upstream buildings in urban areas, which significantly alter wind flow field, consequently, change WDR loadings on downstream building facades compared to the stand-alone building. Part A: four different steady-state RANS models (i.e., standard k−ω, realizable k−ε, RNG k−ε, and standard k−ε) coupled with the Eulerian Multiphase (EM) technique (RANS-EM) are compared and implemented using OpenFOAM-7. These models are validated and verified based on wind-tunnel and field measurement data obtained from the literature for a six-story mid-rise residential building located in an urban area in Vancouver, Canada. The study considers 13 distinct rainfall events, for the test building with/without overhangs. All four RANS models are deemed suitable for modeling WDR in urban areas, while the steady-state standard k-ω RANS-EM approach without incorporating turbulent dispersion showing slightly better performance, thus utilized for the reminder of the study. Part B: a sensitivity analysis is presented on how the upstream buildings influence the WDR loading on a downstream building, denoted as Obstruction Factor. A comparison between the CFD and ISO semi-empirical model shows significant discrepancies, potentially reaching up to factors of 5. Thus, updated Obstruction Factors are suggested to enhance the ISO model for more accurate estimation of WDR loads.

An alternative general model for the effective longitudinal diffusion in chromatographic beds filled with ordered porous particles

The two-zone moment-analysis method for the determination of the dispersion tensor in hierarchical retentive porous media has been adopted to compute and model the effective longitudinal diffusion Deff, or equivalently the B-term band broadening, in chromatographic beds filled with ordered porous particles. On the one hand, this approach offers accurate numerical results for Deff while keeping computational expenses low. On the other hand, it also gives direct insight for the analytical modelling, readily revealings the two main essential quantities (resp. referred to as the mobile-zone and stationary-zone effective diffusion factors γm and γs) that contribute to Deff. Modelling these two main parameters provided us with two new analytical models for Deff: a general one, valid for diluted and concentrated packings and accurate in the whole range of relevant intra-particle diffusion coefficient Dpz, and an approximate one, reliable for diluted packings and accurate also for concentrated packings with low to intermediate values of Dpz. The large advantage of both models is that they do not need any fitting parameter because all the required information is incorporated into the experimentally accessible geometric obstruction factor in the mobile phase originating from the tortuosity of the through-pore space (limiting case of fully solid particles without any retention). These models hence serve as an alternative to the Effective Medium Theory (EMT) models used so far in the literature. To validate the theory, five ordered geometries have been investigated. The accuracy of the general model proposed has been quantified and found to be comparable with that of the 3rd order approximate Torquato model for four geometries, even for macro-porosities close to the close-packing limit. The case of a 2-d triangular array of ellipsoidal particles with different elongations is also investigated to show the general validity and applicability of the models.

Role of site-wise dynamic defects in a resource-constrained exclusion process

We study an exclusion process with site-wise dynamic disorder in a resource constrained environment. The dynamic defects that hinder the particle flux on the lattice stochastically appear and disappear throughout the lattice with a constrained binding rate and a constant unbinding rate, respectively. The effect of constrained resources on the stationary properties of the system has been comprehended in the form of the filling factor. The analytical results replicated by naive mean-field theory accord quite well with the Monte Carlo simulation for faster defects irrespective of the affected hopping rate and slower defects with a large affected hopping rate. For slower defects with a small affected hopping rate, some correlations are observed in the system, leading to the adoption of an enhanced mean-field approach which provides reasonably better approximations than the usual naive-mean field. These correlations slowly fade away with an increase in the affected hopping rate. Our theoretical calculations unify the parameters – the affected hopping rate, defect binding (unbinding) rate, and defect density – that control defect kinetics on the lattice into a single parameter known as the obstruction factor. The repercussions of the obstruction factor have been thoroughly examined by discussing its limiting cases. The phase boundaries that are yielded through different mean-field approaches are uniquely impacted by their corresponding obstruction factor.

Experimental investigation of blast mitigation of pre-fractal obstacles

Obstacles arranged into a pre-fractal shape (Sierpinski carpet) were tested for their blast attenuation abilities using 250 g PE4 at three different scaled distances ( Z = 1.87, 2.24, 2.99 m/kg1/3). Three pre-fractal iterations were tested, as well as free-field tests for comparative purposes. Reductions in peak overpressure up to 26% and peak specific impulse up to 19% were observed, attributed to a mechanism known as ‘trapping’. This mechanism is characterised by a reduction in the ability of a blast wave to advect downstream, with corresponding increases in pressure observed within the bounds of the pre-fractal obstacle. Attenuation magnitudes and areas of reduced pressure and impulse were found to be drastically different with each pre-fractal iteration, with a transition from shadowing to wave trapping as the obstacles more closely resembled true fractals. A linear dependence on a newly-defined obstruction factor ( OF) was found for arrival time, overpressure and impulse at the sensor locations, suggesting that the attenuation of a pre-fractal obstacle is inherently determinable. The results indicate that the mechanism of blast mitigation of pre-fractal obstacles is fundamentally different from singular or arrays of regular obstacles, and could be exploited further to develop novel protective structures with enhanced blast attenuation.

Reservoir crowding in a resource-constrained exclusion process with a dynamic defect.

To understand the complicated transport processes that occur in biological and physical systems, we investigate a constrained totally asymmetric simple exclusion process with a stochastic defect particle. The defect particle might randomly emerge or vanish, resulting in a dynamic defect, and slows down the flow of moving particles when attached to the lattice. Using a mean-field technique, we examine the steady-state characteristics and boundary-layer analysis is provided to comprehend the properties of finite system. In a simplification, our theoretical method unifies three different parameter used to define the defect dynamics into one parameter termed the obstruction factor. It is found that the defect kinetics lead to emergence of phases where the current is defect restricted. The system shows nine phases overall, including bulk-induced and boundary-induced shock phases, with the phase schema showing no more than eight phases depending on the dynamics. We found that variation of obstruction does not lead to qualitative transition in the system, whereas the change in constraint on total particles affect the system qualitatively. All the theoretical outcomes have been validated using extensive Monte Carlo simulations.

An Analytical Model for the Thermal Assessment of a Vertical Double U-Tube Ground-Coupled Heat Pump System in Steady-State Conditions

An analytical model was built to predict the thermal resistance of a vertical double U-tube ground-coupled heat pump that operates under steady-state conditions. It included a geometry obstruction factor for heat transfer throughout the backfill medium due to the presence of the second loop. The verification of the model was achieved by the implementation of five different borehole configurations and a comparison with other correlations in the available literature. The model considered a U-tube spacing range between (2) and (4) times the U-tube outside diameter producing a geometry configuration factor range of (0.29–0.6). The results of the model were utilized for the assessment of the DX ground heat exchanger coupled heat pump system. For similar geometrical configurations, the borehole thermal resistance experienced a decrease as the geometry factor increased. The single U-tube borehole thermal resistance was higher than that of the double U-tube heat exchanger by (10–27)% for the examined geometry configurations. The borehole thermal resistance at tube spacing of twice the tube diameter was higher than the predicted value at the triple diameter and fell in the range of (18–34)%.

A three-stage hybrid model investigating regional evaluation, pattern analysis and obstruction factor analysis for water resource spatial equilibrium in China

The natural distributions of water resources and the spatial positions of the human activities that demand water for production and society are often different, which has globally restricted socioeconomic development, human survival, and ecosystem sustainability. The research significance of water resource spatial equilibrium (WRSE) is to break the limitation of water resources for economic, social and ecological environment development to the greatest extent. To objectively evaluate WRSE, a three-stage hybrid model based on the water-social-economic-natural compound ecosystem (W-SENCE) framework was established in this research. This model includes regional evaluation, pattern analysis and obstruction factor analysis to investigate WRSE quantitatively. To demonstrate the effectiveness of the proposed three-stage hybrid model, empirical research on 31 provincial administrative regions in China was conducted. The results show that: 1) The overall state of water resource spatial equilibrium of China in 2019 is at a poor level with a value of 0.3432 (the result is within the range of 0–1); 2) To improve WRSE, these 8 provinces including Jilin, Gansu, Ningxia, Shaanxi, Shanxi, Chongqing, Qinghai and Yunnan need to formulate policies that focus on both water resource endowment and water resource matching; 3) Eco-environment water consumption in most surveyed provinces accounts for a very small proportion of total water consumption, and 24 out of the 31 provinces can improve WRSE efficiently by increasing eco-environment water consumption appropriately. The proposed three-stage hybrid model provides a novel perspective as well as an important reference for further research on WRSE. Furthermore, the results of this research are essential for decision makers to develop tailored strategies to improve WRSE of China.

Experimental diffusivity of energetic compounds determined by peak parking

Diffusivities of several explosive compounds, as well as other complex organic compounds were experimentally derived using a peak parking methodology. High performance liquid chromatography (HPLC) with stop flow ‘parking’ was used to experimentally determine diffusivity based on band broadening associated with chemical diffusion within the HPLC column. This research builds on prior methods by determining an obstruction factor through comparing benzene diffusion in methanol in a C18 column to the previously published capillary column. The method is useful for structures not easily described by computational chemistry methods or for solvents that do not have association coefficients in published diffusivity models. Using the peak parking method, diffusivities (cm2/s) ranged from 6.29 × 10-7 to 1.06 × 10-6 for hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), 4.82 × 10-5 to 1.26 × 10-4 for 3-nitro-1,2,4-triazol-5-one (NTO), 1.63 × 10-5 to 7.20 × 10-6 for nitroguanidine (NQ), 7.07 × 10-6 to 2.09 × 10-5 for pyrimidine-2-carboxylic acid, and 1.02 × 10-6 to 2.27 × 10-6 for streptomycin. Compared to diffusivities estimated computationally, the empirical diffusivities reported herein estimated by two different methods have percent differences averaging 142%, 174%, 27%, 85%, and 33% for RDX, NTO, NQ, pyrimidine-2-carboxylic acid, and streptomycin, respectively. NTO had experimental diffusivities greater than the computational values, while RDX and streptomycin had experimental diffusivities lower than computational values.

Experimental Investigation of Lift Enhancement and Drag Reduction of Discrete Co-Flow Jet Rotor Airfoil

Rotor airfoil design involves multi-point and multi-objective complex constraints. How to significantly improve the maximum lift coefficient and lift-to-drag ratio of rotor airfoil is a fundamental problem, which should be solved urgently in the development of high-performance helicopter rotor blades. To address this, discrete co-flow jet (DCFJ) technology is one methods with the most potential that can be harnessed to improve the performance of the rotor airfoil. In this study, wind tunnel experiments are conducted to study the effect of DCFJ technology on lift enhancement and drag reduction of OA312 airfoil. Furthermore, the performance improvement effects of the open co-flow jet (CFJ) and DCFJ technologies are studied. In addition, the influence of fundamental parameters, such as the obstruction factor and relative unit length, are analyzed. Results demonstrate that DCFJ technology is better than CFJ technology on the performance enhancement of the OA312 airfoil. Moreover, the DCFJ rotor airfoil can significantly reduce the drag coefficient and increase the maximum lift coefficient and the stall angle of attack. The maximum lift coefficient can be increased by nearly 67.3%, and the stall angle of attack can be delayed by about 12°. The DCFJ rotor airfoil can achieve the optimal performance when the obstruction factor is 1/2 and the relative unit length is 0.025.

ANALISIS KINERJA RUAS JALAN TERHADAP PASAR TRADISIONAL

Way kandis market is one of the market center in marketing area in Bandar Lampung City whichhas the highestactyvity especially in busy tie, the problem is about the traffic flow conflictwhich causes traffic jam.
 This research aims to know about the condition of road capacity in Ratu dibalau street to the influence of the market activity in Way kandis market bby evaluating the influenceof the obstruction factor with the analysis ofcounting such the vehicles volume, the speed of vehicles and the road capacity based on the result of the surveying in the area so that it can solve the problemswhich happen in that area.
 Based on discution result from MKJI 1997 counting, it got the value of satitation degree in Ratu dibalau street in front of way kandis market is about 0,64 with the speed of vehicles is about 32 km/hr and includes to the highest obstructions factor.
 This is show thet Ratu dibalau in from of the way kandis market has a problem which causes the traffic jam with the time of speed is about 11,25 / second, this is from the problems which influence to the walker and vehicles park or stop. 
 
 
 Keywords: road performance, traditional market, way kandis

Capacity Building Kelembagaan Komisi Informasi Provinsi Lampung dalam Meningkatkan Penyelenggaraan Keterbukaan Informasi Publik di Provinsi Lampung

Transparency in government management is important to continue to be improved. The existence of a good government management is the increasing of public trust through public information disclosure. The Information Commission as an implementor in the implementation of law No. 14 of 2008 on Public Information Disclosure must continue to develop the capacity of institutions in order to provide maximum performance so as to encourage the implementation of public information disclosure in Lampung Province. This research aimed to describe the institutional capacity building efforts conducted by the Lampung Provincial Information Commission as well as identify inhibitory factors in the effort. The research method used a qualitative approach. The results of the study generally showed that the Lampung Provincial Information Commission began to make institutional capacity building efforts through the development of physical resources, the development of operational processes, and the development of human resources. Overall all three aspects have gone pretty well.Aspects of physical resource development are starting to go well due to structural changes in the institution that have a good impact on other aspects. In terms of operational development, efforts are made that motivate employees through incentives, personnel addition and building good cooperation and coordination. Aspects of human resource development are trying to be built through training efforts. The obstruction factor in capacity building efforts found to be related to legal devices as well as agency budgets that are not yet fully independent.

Development of Analytical Model for a Vertical Single U-Tube Ground-Coupled Heat Pump System

An analytical model was built to study the thermal design of a single vertical U-tube coupled heat pump under steady-state conditions. It was based on the philosophy of U-tube replacement by an equivalent thermal resistance situated between the heat transfer medium that flows inside the tube and the borehole boundary. An obstruction factor was introduced to account for the reduction of heat flow from or to a tube in the borehole due to the presence of the second leg of the U-tube. Two Copper U-tubes with wall factors of (12.5) and (14.29) were implemented to comprise several borehole configurations to verify the present work. The shank spacing was ranged between (2) and (4) times the U-tube outside diameter producing shank spacing to borehole diameter ratio range of (0.29-0.59). The model was utilized for the assessment of DX ground heat exchangers works as a condenser for cooling purposes. Reducing of the tube spacing to tube outside diameter ratio from (3.3) to (2) for both tube wall factors showed a rise for the borehole thermal resistance in the range of (22-54)% and (26.5-28)% predicted at wall factors of (12.5) and (14.29) respectively.

A Methodology for the Estimation and Modelling of the Obstruction Factor in the Expression for Mesopore Diffusion in Reversed-Phase Liquid Chromatography Particles

An experimental methodology for the determination of the obstruction factor in the expression for mesopore diffusion in Zorbax Eclipse Plus C18 reversed-phase particles is proposed. The method uses peak parking experiments conducted on particles that were previously stripped of their stationary phase by flushing the column with trifluoroacetic acid at a temperature of 60°C. Further using pure organic solvents as the mobile phase, any potential retention or surface diffusion effect is omitted. To avoid interference between the parked peaks and baseline disturbances typically occurring when switching on and off the flow, peak parking experiments were carried out in a set-up wherein two identical columns were used in parallel. This set-up allowed to maintain the flow through the detector at all times, by redirecting the flow from one column to the other during the peak parking experiments. Several tracer molecules (ionic and deuterated tracers) were compared and it was found that the use of deuterated molecules provides the best possible coverage of the accessible space of the mesopore volume. Interpreting the peak parking responses obtained with these tracers with a model based on the effective medium theory (EMT) subsequently provided an estimate of the value of the mesopore diffusion obstruction factor γmp. Taking the well-established pore hindrance factor F(λ) correction into account, the obtained experimental γmp-values are more in agreement with the tortuous and constricted diffusion paths one can expect in the void space within a structure resembling a monolithic skeleton with tetrahedral connectivity rather than in the void space formed by a packing of nanospheres. This is also more in line with the measured internal porosity values lying around εpz=0.5, whereas a packing of nanospheres would rather correspond to an εpz of 0.4. As such, the presented protocol provides a means to infer the internal mesopore structure of reversed-phase particles.

Evaluation of Water Resources Carrying Capacity and Its Obstruction Factor Analysis: A Case Study of Hubei Province, China

The carrying capacity of water resources can provide a reference index for regional economic construction and development. Hubei produces 13.2% of China’s hydroelectric energy and 4% of China’s water resources, highlighting that the reservoir group in Hubei province is relatively developed. In the current research on water resources carrying capacity, only the amount of water resources was considered; the benign mutual feeding effect of regional reservoirs on regional water resources carrying capacity was not reflected upon. In order to guide social and economic activities better, this paper proposes the addition of reservoir water storage to the calculation of water resources carrying capacity as a separate indicator. In this paper, the cloud model method was used to calculate the water resources carrying capacity of Hubei province and the Dematel method was used to determine the degree of importance of reservoir water storage. Finally, the degree of obstacles was also considered to discuss the main factors affecting the water resources carrying capacity of Hubei province. In the system discussed in this paper, the degree of influence and the affected degree of reservoir water storage were found to be 1.2915 and 0.5759, respectively. The calculation results showed that Hubei province’s water resources carrying capacity has been increasing every year and the amount of water resources per unit area was the main restricting factor, with the obstacle degree reaching 19.24% of the average annual level.

Deglutição: impacto dos movimentos da laringe sobre a proteção das vias aéreas

Introduction: Asthma and allergic rhinitis have been considered as manifestations of the same syndrome, since they have common epidemiological, genetic and pathophysiological bases. The interaction between difficulty in breathing function, asthma and allergic rhinitis may promote changes in the stomatognathic system, such as chewing and swallowing functions, as well as anatomical and functional changes in facial and somatic growth. Objective: To perform an integrative review of chewing and swallowing assessment in children and teenagers with rhinitis and asthma. Materials and Methods: We searched the Lilacs, MedLine, PubMed and Scielo databases for articles on swallowing and chewing in children and teenagers with asthma and rhinitis in January and February 2017, and this research was updated in June 2018. Results: A total of 2,537 articles were found, but only five presented the eligibility criteria. Discussion: Few studies regarding the topic were found. Of the five articles selected, three inferred to find no alterations and two found altered patterns, relating to the nasal obstruction factor. More research is needed on the subject. Conclusion: There is no scientific evidence to support the presence of chewing and swallowing disorders due to asthma and rhinitis in children and teenagers.

Alterações da mastigação e deglutição secundárias à rinite alérgica e à asma em crianças e adolescentes – revisão integrativa

Introdução: A asma e a rinite alérgica têm sido consideradas manifestações de uma mesma síndrome, uma vez que apresentam bases epidemiológicas, genéticas e fisiopatológicas comuns. A interação entre a dificuldade na função de respiração, a asma e a rinite alérgica podem promover alterações no sistema estomatognático, como as funções de mastigação e a deglutição, além de modificações anatômicas e funcionais, no crescimento facial e somático. Objetivo: Realizar uma revisão integrativa da avaliação da mastigação e deglutição em crianças e adolescentes com rinite e asma. Materiais e Métodos: Foi realizada uma pesquisa nas bases de dados Lilacs, MedLine, PubMed e Scielo, sobre artigos que abordavam a deglutição e mastigação em crianças e adolescentes com asma e rinite no período de janeiro e fevereiro de 2017, e a pesquisa foi atualizada em junho de 2018. Resultados: Foram encontrados 2.537 artigos, mas apenas cinco apresentaram os critérios de elegibilidade. Discussão: Poucos estudos referentes ao tema foram encontrados. Dos cinco artigos selecionados, três inferiram não encontrar alterações e dois encontraram padrões alterados, relacionando com o fator de obstrução nasal. É necessário que mais pesquisas sejam realizadas sobre o tema. Conclusão: Não há evidências científicas que afirmem a presença de alterações de mastigação e deglutição decorrentes da asma e da rinite em crianças e adolescentes.

A challenge in anaerobic digestion of swine wastewater: recalcitrance and enhanced-degradation of dietary fibres.

Dietary fibres are main substances in the pig's feed. Because of the recalcitrance, they could enter swine wastewater and become a serious obstruction factor for the anaerobic digestion process. In this work, three dietary fibres abundant in pig feedstocks: Wheat Bran Fibre (WBF), Alfalfa Fibre (AF) and Rice Chaff Fibre (RCF) were chosen and their anaerobic degradability was determined. The results showed that the biochemical methane potential in 10days (BMP10) of WBF, AF and RCF was 258, 176 and 86mL/g-VS, respectively. The size, purity, crystallinity, and lignin coating in particular, were found having influences on the anaerobic biodegradability of dietary fibres. To surprise, a negative rather than positive effect was observed for the direct addition of extraneous cellulase into the anaerobic digestion systems, leading to a longer lag time and a smaller BMP10. The enhancement was achieved for the addition of extraneous bacteria in the form of anaerobic granular sludge (AnGS), shortening the lag time of WBF and AF by 36% and 13%, respectively. By high-throughput sequencing analysis, abundant protein and amino acids degraders found in anaerobic activated sludge (AnAS) could degrade the exogenous enzymes. Abundant members affiliated to the family Anaerolineaceae, and Syntrophobacteraceae in AnGS, related to the cellulolytic and syntrophic activity respectively, probably contribute to the acceleration effect of AnGS.

Combining tomographic imaging and in silico computation for rapid effective PEMFC cathode transport characterization

An approach for determination of effective oxygen diffusivity within a polymer electrolyte membrane fuel cell cathode catalyst layer by combining tomography and geometric calculations is presented. Accurate determination of effective oxygen diffusivity is critical for modeling and characterization of cathode design architectures. In silico geometric characterization methods exploit the increasing availability, capability, and decreasing cost of tomographic imaging and high-performance computing. Geometric methods can be made simple and fast and could accelerate efforts to iteratively improve cathode design. The method described herein relied on mathematically exact and statistically significant definitions of geometric tortuosity and geometric constrictivity, in addition to porosity. To demonstrate generality and robustness, a correlation for obstruction factor underpinned by these parameters was statistically induced from hundreds of instantiations of stochastic cathode microstructures generated by a simulated annealing method and validated versus the obstruction factor of real cathode microstructures obtained separately by Star and Fuller in a previous publication and Ziegler et al. at the University of Freiburg. This work demonstrated the utility and viability of adopting a combined tomography/geometric-computational approach for determination of the effective diffusivity of reactant in the cathode catalyst layer and its underlying transport properties. This analysis was based on a conventional cathode microstructure with platinum catalyst, carbon black support, and perfluorosulfonic acid ionomer. However, the method could easily be extended to platinum group metal-free cathodes in which accurate characterization may be of even greater importance due to the thicker cathode layers required in these systems. This approach could be widely adopted and relied upon for characterization as the materials and processing conditions of cathode layers are iteratively tested and optimized.

OPTIMALISASI RETRIBUSI PASAR DALAM MENINGKATKAN PENDAPATAN ASLI DAERAH KABUPATEN DOMPU PROVINSI NUSA TENGGARA BARAT

ABSTRACT
 Below Market is one of the main economic’s activator of Dompu’s society. Below Market is located at the urban area in Dompu city so it needs to be manage and arrange in order to keep the society’s Economics consist well. Based on that thing, the writer interest to do a research by a tittle “optimization the levies of below Market in order to increase the local revenue of Dompu regency West Nusa Tenggara province. The purpose of this Research was to determine optimization of a levy Market to increase the local revenue, to know the obstruction factor of managing a levy Market and also to know the efforts that the government do to manage a levy Market. A method that the writer use is descriptive qualitative method using inductive approach. The resource of the data that use is secondary and primary data. To collecting the data the writer do the interview and documentation also use the reduction of data analysis. Presentation and Verification. The Research located at BAPPENDA at Dompu Regency. The result of this research showed that optimization of the levies below Market can not give such a high contribution of the local revenue in Dompu Regency, because the result does not maksimum yet. Besides, the realization of the local revenue still can not reach the target, and the less awareness of the levy payer, and also less of the Supervision in the Regency, less of socialization, less of tool and infrastructure. That it is why we hope that government and the society can support in order to decrease the problem and Gide the Solutions to solven the levies of below Market problems.
 Keywords: optimization, retribution, local revenue

Application of the Improved Spacer Grid Model in Subchannel Analysis Code

In most subchannel analysis codes, spacer grids are simulated using an effective loss coefficient that can account only for the spacer grid’s mean axial effect on the pressure drop. Since the mixing vane spacer grid (MVG) in a rod bundle has great influence on local flow fields, neglecting the effect of mixing vanes will degrade fidelity and resolution in thermal-hydraulic calculation. This paper focuses on improving the spacer grid model in subchannel analysis. First, cross-flow mixing effects of MVGs are accounted for by applying the distributed resistance method. By choosing resistance correlation appropriately and considering the geometric dimensions of mixing vanes, the source term of mixing vanes can be represented quantitatively in the axial and lateral momentum equations of a subchannel analysis code. Second, the Carlucci model is used to calculate mixing rates, and obstruction factor Fobs is introduced to consider turbulent mixing effects caused by spacer grids. The improved MVG cross-flow model and turbulent mixing model are implemented in the subchannel code ATHAS. Validation is provided for the 5 × 5 rod bundle experiments provided by Karoutas et al. [Proc. 7th Int. Mtg. Nuclear Reactor Thermal-Hydraulics (NURETH-7), Saratoga, New York (1995)] and high-quality experimental data provided by the Organisation for Economic Co-operation and Development/U.S. Nuclear Regulatory Commission Pressurized Water Reactor Subchannel and Bundle Test (PSBT) benchmark to demonstrate their effects and accuracy. From the validation, it can be concluded that the calculated lateral velocities agree well with those provided by the experimental data. In addition, the improved cross-flow and turbulent mixing models significantly increase the accuracy of predictions of exit subchannel coolant temperatures, with reduction in root-mean-square error to be 2.27 K.