Volume 2: Computational Fluid Dynamics最新文献_第3页

Three Dimensional Simulation of the Effect of Windcatcher’s Inlet Shape 捕风器入口形状影响的三维模拟

Volume 2: Computational Fluid Dynamics Pub Date : 2019-11-20 DOI: 10.1115/AJKFLUIDS2019-5385

P. Abdo, Rahil Taghipour, B. P. Huynh

{"title":"Three Dimensional Simulation of the Effect of Windcatcher’s Inlet Shape","authors":"P. Abdo, Rahil Taghipour, B. P. Huynh","doi":"10.1115/AJKFLUIDS2019-5385","DOIUrl":"https://doi.org/10.1115/AJKFLUIDS2019-5385","url":null,"abstract":"\u0000 Windcatcher has been used over centuries for providing natural ventilation using wind power, it is an effective passive method to provide healthy and comfortable indoor environment. The windcatcher’s function is based on the wind and on the stack effect resulting from temperature differences. Generally, it is difficult for wind to change its direction, and enter a room through usual openings, the windcatcher is designed to overcome such problems since they have vertical columns to help channel wind down to the inside of a building. The efficiency of a windcatcher is maximized by applying special forms of opening and exit. The openings depend on the windcatcher’s location and on its cross sectional area and shape such as square, rectangular, hexagonal or circular. In this study the effect of the inlet design is investigated to achieve better air flow and increase the efficiency of windcatchers. To achieve this, CFD (computational fluid dynamics) tool is used to simulate the air flow in a three dimensional room fitted with a windcatcher based on the different inlet designs. The divergent inlet has captured the highest air flow with a difference of approximately 3% compared to the uniform inlet and 5% difference compared to the bulging-convergent inlet.","PeriodicalId":346736,"journal":{"name":"Volume 2: Computational Fluid Dynamics","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126442134","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Modeling and CFD Analyses of Gear Pump in OpenFOAM OpenFOAM齿轮泵的建模与CFD分析

Volume 2: Computational Fluid Dynamics Pub Date : 2019-11-20 DOI: 10.1115/ajkfluids2019-5435

G. Shoukat, Kamran Siddique, M. Sajid

{"title":"Modeling and CFD Analyses of Gear Pump in OpenFOAM","authors":"G. Shoukat, Kamran Siddique, M. Sajid","doi":"10.1115/ajkfluids2019-5435","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-5435","url":null,"abstract":"\u0000 Turbomachinery plays a key role in process and manufacturing industries. The interplay between power, flow rates and pressure output remain an interesting research area. To support specific processes in the industry, each pump or compressor must be fine-tuned for peak performance. As trend shifts from large organizations to entrepreneurial startups, spending significant costs on licensing of commercially available CFD softwares becomes unfeasible. This paper investigates the use of OpenFOAM – open source CFD package towards the analysis of gear pumps. The solution employs dynamic meshing and snappyHexMesh library in a single study. To validate the numerical model developed under OpenFoam’s environment, experimental studies were carried out. The pressure output of the pump was measured at four different RPMs — 200, 250, 300 and 400. An excellent agreement between experimental and numerical studies was seen at relatively higher RPMs. The numerical studies further explored the pulsating flow, recorded the variation between a constant maximum and minimum pressure value for each RPM. The variation in pressure was observed to increase at higher RPMs. The agreement between experimental and numerical findings established the utility of OpenFoam in investigating pump action.","PeriodicalId":346736,"journal":{"name":"Volume 2: Computational Fluid Dynamics","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130170299","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Evaluation of Pressure-Strain Correlation As a Basis for Development of a Physics-Based Transition Onset Marker 压力-应变相关性评估作为开发基于物理的过渡开始标记的基础

Volume 2: Computational Fluid Dynamics Pub Date : 2019-07-28 DOI: 10.1115/ajkfluids2019-5418

S. Muthu, S. Bhushan, D. K. Walters

引用次数: 2

Study of a Multistage Canned Motor Pump: Simulation, Optimization and Validation 多级屏蔽泵的研究:仿真、优化与验证

Volume 2: Computational Fluid Dynamics Pub Date : 2019-07-28 DOI: 10.1115/ajkfluids2019-5157

H. Benigni, M. Mosshammer, H. Jaberg

{"title":"Study of a Multistage Canned Motor Pump: Simulation, Optimization and Validation","authors":"H. Benigni, M. Mosshammer, H. Jaberg","doi":"10.1115/ajkfluids2019-5157","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-5157","url":null,"abstract":"\u0000 This paper describes the detailed analysis of a multistage canned motor pump with an additional radial suction impeller by means of CFD simulations to determine the main losses and to establish optimization potential of the hydraulic parts. In addition to the main flow channels of the impeller, the degree of detail of the analysis also includes the front and rear impeller side spaces, relief holes, gaps, return sections and all hydraulically wetted surfaces of the canned motor. The model presented was successively generated and already at a very early stage it was obvious that the model has to contain all details mentioned in order to provide valuable simulation results. For the impeller, the gaps and the pressure relief holes primarily structured meshes were used with a final model of the existing pump consisting of more than 35 million nodes. The behavior of the main components was analyzed in detail and additionally the CFD simulations — stationary and transient — with scale resolving turbulence models were validated by means of model tests. Furthermore, a comprehensive loss analysis of the existing pump was performed to verify the optimization potential. The subsequent optimization was realized semi-automated. A tight corset of requirements, e.g. identical head curve, suction behavior and dimensions, has been defined to guarantee retrofit capability of the pump analyzed in order to fully satisfy the demand for a constant delivery head curve and at the same time to provide for a relative increase of the optimum efficiency by 25% and in a wide range of applications by at least 20%. The optimized model was manufactured based on rapid prototyping and tested in the laboratory. The results show a satisfying correlation between the numerically predicted and the measured results on the test rig and prove the high quality of the numerical simulations run.","PeriodicalId":346736,"journal":{"name":"Volume 2: Computational Fluid Dynamics","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129453123","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

DSMC Simulation of Rarefied Gas Flow Over a Wall Mounted Cube 壁挂式立方体上稀薄气体流动的DSMC模拟

Volume 2: Computational Fluid Dynamics Pub Date : 2019-07-28 DOI: 10.1115/ajkfluids2019-5447

D. Nabapure, R. Murthy

引用次数: 5

Hydrodynamic Evaluation of Microtiter Plate Assay Using Computational Fluid Dynamics for Biofilm Formation 生物膜形成的计算流体动力学微滴板测定的流体动力学评价

Volume 2: Computational Fluid Dynamics Pub Date : 2019-07-28 DOI: 10.1115/ajkfluids2019-5425

R. Zahra, A. Khan, Muhammad Sajid

{"title":"Hydrodynamic Evaluation of Microtiter Plate Assay Using Computational Fluid Dynamics for Biofilm Formation","authors":"R. Zahra, A. Khan, Muhammad Sajid","doi":"10.1115/ajkfluids2019-5425","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-5425","url":null,"abstract":"\u0000 Biofilms are complex surface associated communities where bacterial cells are enclosed by self-produced extra cellular polymeric substances (EPS), mainly consisting of exopolysaccharides, proteins and extracellular DNA. Treatment of biofilm associated persistent infections is an emerging issue for clinicians as bacterial cells adhere with human epithelial cells or indwelling medical devices such as implants and catheters, used in urinary tract and respiratory infections. Several methods are in practice to assess the biofilm formation of bacterial strains. Most of these are phenotypic methods which include Congo red assay (CRA), Air liquid interface (ALI), tissue culture plate method and Microtiter plate assay (MTPA). MTPA is considered as a standard screening method for comparing adherence pattern and is the most widely used quantitative method for detection of biofilm formation. Generally, the assay is performed under standard static conditions and little is known about the hydrodynamics in the microtiter plates. A few studies have applied computational fluid dynamics (CFD) simulations to describe flow pattern in microtiter plates during biofilm production and optimized the suitable conditions to detect the biofilm formation which have proven to be efficient. In this work the dependencies of biofilm formation on the hydrodynamics in microtiter plate assays were evaluated using OpenFOAM® an open-source toolbox for numerical simulation. It was found that higher flow rates increase the nutrient availability, promote cell growth, and attachment pattern with increased production of exopolymer, while the increase in flow velocity increases the shear rate causing erosion and disassembly of biofilm production because of detachment from the surface.","PeriodicalId":346736,"journal":{"name":"Volume 2: Computational Fluid Dynamics","volume":"78 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114305700","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Validation and Development of DNS Database for Low Prandtl Numbers in Rod Bundle 棒束低普朗特数DNS数据库的验证与开发

Volume 2: Computational Fluid Dynamics Pub Date : 2019-07-28 DOI: 10.1115/ajkfluids2019-5036

J. Lai, E. Merzari, Y. Hassan, A. Obabko

{"title":"Validation and Development of DNS Database for Low Prandtl Numbers in Rod Bundle","authors":"J. Lai, E. Merzari, Y. Hassan, A. Obabko","doi":"10.1115/ajkfluids2019-5036","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-5036","url":null,"abstract":"\u0000 Difficulty in capturing heat transfer characteristics for liquid metals is commonplace because of their low molecular Prandtl number (Pr). Since these fluids have very high thermal diffusivity, the Reynolds analogy is not valid and creates modeling difficulties when assuming a turbulent Prandtl number (Prt) of near unity. Baseline problems have used direct numerical simulations (DNS) for the channel flow and backward facing step to aid in developing a correlation for Prt. More complex physics need to be considered, however, since correlation accuracy is limited. A tight lattice square rod bundle has been chosen for DNS benchmarking because of its presence of flow oscillations and coherent structures even with a relatively simple geometry.\u0000 Calculations of the Kolmogorov length and time scales have been made to ensure that the spatial-temporal discretization is sufficient for DNS. In order to validate the results, Hooper and Wood’s 1984 experiment has been modeled with a pitch-to-diameter (P/D) ratio of 1.107. The present work aims at validating first- and second-order statistics for the velocity field, and then analyzing the heat transfer behavior at different molecular Pr. The effects of low Pr flow are presented to demonstrate how the normalized mean and fluctuating heat transfer characteristics vary with different thermal diffusivity. Progress and future work toward creating a full DNS database for liquid metals are discussed.","PeriodicalId":346736,"journal":{"name":"Volume 2: Computational Fluid Dynamics","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114516432","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Comparison of a Singularity- and an Inverse Design Method for Axial Flow Fans Based on Numerical Simulations 基于数值模拟的轴流风机奇异设计与反设计方法的比较

Volume 2: Computational Fluid Dynamics Pub Date : 2019-07-28 DOI: 10.1115/ajkfluids2019-4713

A. Theis, M. Böhle

{"title":"Comparison of a Singularity- and an Inverse Design Method for Axial Flow Fans Based on Numerical Simulations","authors":"A. Theis, M. Böhle","doi":"10.1115/ajkfluids2019-4713","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-4713","url":null,"abstract":"\u0000 In this contribution two different design methods for axial flow profiles are presented. A direct method based on a singularity method (SDM) is compared with an inverse design method (IDM). For the application of the SDM a profile is used with a circular arc camber line and a thickness distribution of bisuper-ellipses. The stagger angle is adjusted in such a way that the turning of the flow on the cross section is realized. For the adjustment of the stagger angle of the cross section the fast working SDM is applied. The stagger angle is varied until the corresponding deflection angle calculated by the SDM is reached. The IDM consists of an inverse boundary layer- and an inverse potential theory method. Along the suction side the shape factor of the boundary layer is prescribed conveniently for the laminar and turbulent part. The velocity distribution at the outer edge of the boundary is calculated by an inverse boundary layer method. On the pressure side the velocity distribution is chosen in such a way that a corresponding circulation is realized for turning the flow. Finally, the whole geometry of the cascade is calculated by the inverse potential theory method.\u0000 The examination of one cross section is done numerically using the commercial RANS Solver ANSYS CFX. Low Reynolds number of approximately 4.25 × 105 and the transition from laminar to turbulent are taken into account by the transition SST model.","PeriodicalId":346736,"journal":{"name":"Volume 2: Computational Fluid Dynamics","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123469417","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Numerical Investigation of Pressure Pulsation in Vaneless Region of a High Speed Centrifugal Pump 高速离心泵无叶区压力脉动的数值研究

Volume 2: Computational Fluid Dynamics Pub Date : 2019-07-28 DOI: 10.1115/ajkfluids2019-4912

Zeng Yongshun, M. Yang, Zhai Yuqing, Z. Yao, Fujun Wang, R. Xiao

{"title":"Numerical Investigation of Pressure Pulsation in Vaneless Region of a High Speed Centrifugal Pump","authors":"Zeng Yongshun, M. Yang, Zhai Yuqing, Z. Yao, Fujun Wang, R. Xiao","doi":"10.1115/ajkfluids2019-4912","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-4912","url":null,"abstract":"\u0000 The pressure pulsation due to rotor-stator interaction (RSI) is unavoidable for high-speed centrifugal pump when operating under different conditions. The frequency components of pressure pulsation in the vaneless region are the most complex, and the pressure pulsation characteristic plays an important role in pump structural stress analysis. A numerical simulation method is used to obtain the hydraulic performances of a high-speed centrifugal pump with 9857 r/min at the range of flow rates between 48.1 to 155.0 m3/h. The head and efficiency under different operating conditions have good agreement with experimental results, with maximum deviations in 3.82% and 5.37%, respectively. The results show that the level of the pressure pulsation from the inlet to the outlet of the impeller increased gradually, and the pressure pulsations between the short blades are greater than that between the long and short blades. In the diffuser, the pressure pulsation is the highest near the tongue, whereas it is lower in the region between the two tongues, and this region is defined as the vaneless region. The pressure contours in the vaneless region almost have no change, while they near the tongue are densely distributed, revealing the mechanism of uneven pressure pulsation distribution. Moreover, there is a high radial velocity distribution near the tongue in the vaneless region, indicating that there may be a jet-wake pattern occured in this region.","PeriodicalId":346736,"journal":{"name":"Volume 2: Computational Fluid Dynamics","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121964240","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

A New Immersed Stress Method Based on Volume Average 一种新的基于体积平均的沉应力法

Volume 2: Computational Fluid Dynamics Pub Date : 2019-07-28 DOI: 10.1115/ajkfluids2019-4697

T. Fukada, S. Takeuchi, T. Kajishima

引用次数: 0