Advances in Fluid Mechanics XII最新文献_第2页

NUMERICAL STUDY ON THE EFFECT OF TUNNEL ASPECT RATIO ON THE PLUG-HOLING PHENOMENA IN SHALLOW UNDERGROUND TUNNELS 浅埋地下隧道长径比对塞孔现象影响的数值研究

Advances in Fluid Mechanics XII Pub Date : 2018-07-10 DOI: 10.2495/AFM180201

K. Hong, Junyoung Na, K. H. Sung, H. Ryou

{"title":"NUMERICAL STUDY ON THE EFFECT OF TUNNEL ASPECT RATIO ON THE PLUG-HOLING PHENOMENA IN SHALLOW UNDERGROUND TUNNELS","authors":"K. Hong, Junyoung Na, K. H. Sung, H. Ryou","doi":"10.2495/AFM180201","DOIUrl":"https://doi.org/10.2495/AFM180201","url":null,"abstract":"Natural ventilation systems (NVS) have been widely used in shallow underground tunnels due to convenience in installation, maintenance and low cost compared with mechanical ventilation systems. In the NVS, smoke ventilation rate is mainly determined by the flow rate through the vertical shaft due to the stack effect. In practice, fresh air under smoke layer directly flows into the shaft and the phenomena is defined as “plug-holing”. When the plug-holing occurs in the NVS, the actual smoke ventilation rate becomes smaller than the design value. The plug-holing phenomenon correlates relative ratio between ceiling jet flow and buoyant flow immediately below the shaft. Therefore, tunnel geometrics and fire size mainly affect the plug-holing phenomena. Especially, the area of the ceiling plays an important role in the properties of smoke layer such as temperature and velocity, thus the crosssectional aspect ratio of a tunnel can affect the occurrence of plug-holing. In this study, we numerically investigated the effect of tunnel aspect ratio on the plug-holing phenomena in shallow underground tunnels. Numerical analysis was performed with changing the tunnel aspect ratio which is defined as the ratio of the height to width of tunnel. As a result, as the aspect ratio decreases, the velocity and temperature of the smoke layer decreases and it means that the buoyancy and momentum force are diminished. The momentum force decreases more rapidly than the buoyancy force, so the fresh air can be entrained into the shaft. Therefore, the potential for the occurrence of plug-holing increases as the aspect ratio decreases.","PeriodicalId":261351,"journal":{"name":"Advances in Fluid Mechanics XII","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128815986","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

FUNDAMENTAL SOLUTIONS IN COMPUTATIONAL FLUID DYNAMICS 计算流体动力学的基本解

Advances in Fluid Mechanics XII Pub Date : 2018-07-10 DOI: 10.2495/AFM180011

L. Skerget, A. Tadeu, J. Ravnik

{"title":"FUNDAMENTAL SOLUTIONS IN COMPUTATIONAL FLUID DYNAMICS","authors":"L. Skerget, A. Tadeu, J. Ravnik","doi":"10.2495/AFM180011","DOIUrl":"https://doi.org/10.2495/AFM180011","url":null,"abstract":"With the boundary element method (BEM), the velocity-vorticity formulation is introduced and the overall Navier–Stokes problem is partitioned into the kinetic and kinematic parts. For a general viscous flow, the kinetics is formulated as a differential nonlinear vorticity diffusion-convective transport equation, whilst the kinematics of the fluid flow computation is governed by the Biot– Savart integral representation. This work presents an overview of the numerical simulation of transport phenomena in fluid flow using a different type of Green’s fundamental solutions in the context of BEM. The kinetic diffusion-convective partial differential equations (PDEs) represent, respectively, mixed elliptic-hyperbolic or parabolic-hyperbolic types of PDEs, governing the steady or time dependent transport phenomena in fluid flow, e.g. transfer of heat energy, momentum, vorticity, etc. Applying the singular integral representations has important numerical and physical aspects as a consequence of the fundamental solutions applied. The solution algorithm is based on improved macro-elements concept using mixed-boundary elements. The numerical model uses quadratic approximation for all field functions and linear approximation of the fluxes over space and constant approximation over time for all field functions.","PeriodicalId":261351,"journal":{"name":"Advances in Fluid Mechanics XII","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114623618","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

THE EFFECT OF AN ASYMMETRIC SUBMARINE TRENCH ON THE EFFICIENCY OF AN OSCILLATING WATER COLUMN DEVICE IN A TWO-LAYER FLUID 非对称海沟对两层流体中振荡水柱装置效率的影响

Advances in Fluid Mechanics XII Pub Date : 2018-07-10 DOI: 10.2495/AFM180141

A. Medina-Rodríguez, Alejandro Díaz Martínez, R. S. Casarín

引用次数: 2

HEAT TRANSFER ANALYSIS FOR LI-ION BATTERY PACKAGE WITH A HYBRID THERMAL MANAGEMENT SYSTEM USING PHASE CHANGE MATERIAL AND FORCED CONVECTION 采用相变材料和强制对流混合热管理系统的锂离子电池组传热分析

Advances in Fluid Mechanics XII Pub Date : 2018-07-10 DOI: 10.2495/AFM180041

Joon Ahn, J. Song, Joon-Sik Lee

{"title":"HEAT TRANSFER ANALYSIS FOR LI-ION BATTERY PACKAGE WITH A HYBRID THERMAL MANAGEMENT SYSTEM USING PHASE CHANGE MATERIAL AND FORCED CONVECTION","authors":"Joon Ahn, J. Song, Joon-Sik Lee","doi":"10.2495/AFM180041","DOIUrl":"https://doi.org/10.2495/AFM180041","url":null,"abstract":"Battery charging and performance maintenance is one of the core technologies of electric vehicles. The performance of the battery is temperature-sensitive and the temperature should be kept within a certain range. Due to the nature of the car being driven and parked in the outdoors with extreme temperature changes, an efficient thermal management system is required. Cooling fans are mainly used for thermal management, but the power to drive the fans is used and the cooling capacity is limited. A method of using phase change materials has been proposed. The phase change material has a disadvantage in that the operating point is limited and heat transfer control is not easy. In this study, we propose a hybrid thermal management system with a cooling fan and a phase change material filled inside the battery pack. In order to investigate the cooling performance of the system, a series of CFD has been conducted for the hybrid cooling unit of the Li-ion battery pack in which the phase change and forced convection by implementing an immersed boundary method handling the conjugate heat transfer with a phase change. The simulation results show that the uniformity of the inter-cell temperature can be greatly improved when the phase-change material is filled.","PeriodicalId":261351,"journal":{"name":"Advances in Fluid Mechanics XII","volume":"135 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115566701","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

GLOBALLY VERSUS COMPACTLY SUPPORTED RBFS 全局支持与紧凑支持的RBFS

Advances in Fluid Mechanics XII Pub Date : 2018-07-10 DOI: 10.2495/AFM180251

E. Kansa

引用次数: 0

EFFECT OF NOZZLES’ CHARACTERISTICS ON PV AEROMECHANICAL SYSTEMS 喷嘴特性对pv气动系统的影响

Advances in Fluid Mechanics XII Pub Date : 2018-07-10 DOI: 10.2495/AFM180231

Liron Shani, Ronen S. Lautman, B. Nishri

引用次数: 0

PRESSURE MEASUREMENTS ON THE GATE SUBJECTED TO SUBMERGED HYDRAULIC JUMP 水下液压跳闸的压力测量

Advances in Fluid Mechanics XII Pub Date : 2018-07-10 DOI: 10.2495/AFM180291

S. Smok, E. Demirel

{"title":"PRESSURE MEASUREMENTS ON THE GATE SUBJECTED TO SUBMERGED HYDRAULIC JUMP","authors":"S. Smok, E. Demirel","doi":"10.2495/AFM180291","DOIUrl":"https://doi.org/10.2495/AFM180291","url":null,"abstract":"Vertical gates are commonly used to control the flow and to measure the discharge in irrigation canals and natural streams. Submerged hydraulic jump forms downstream of a gate when the tail water depth is greater than the conjugate depth of the free jump. Interaction of the recirculating flow with the incoming flow with high momentum creates surface pressures fluctuations on the gate. In this study, experimental studies were carried out in a laboratory flume under different flow conditions of jet Froude number and submergence factor in order to provide a clear understanding of how the vortex induced pressure fluctuations affect the gate stability. Simultaneous pressure measurements were made using pressure sensors attached to the different locations on the gate lip. Spatial variations of time-averaged and instantaneous pressure coefficients at the gate lip were evaluated for different inlet Froude numbers and submergence factors. Although the submergence factor is not very effective on the distribution of mean pressure coefficient, Froude number can significantly affect the mean pressure distributions. On the other hand, spatial distributions of instantaneous pressure coefficient strongly depend on both jet Froude number and submergence factor. Frequency spectra of the lift pressures reveal that the magnitude of the spectra increases as the Froude number increases and the slope of the spectra is independent of both Froude number and submergence factor.","PeriodicalId":261351,"journal":{"name":"Advances in Fluid Mechanics XII","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130110479","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

SCALE-RESOLVING SIMULATION OF FLOW THROUGH A PERIODIC ARRAY OF CUBES 通过立方体周期阵列的流动的尺度解析模拟

Advances in Fluid Mechanics XII Pub Date : 2018-07-10 DOI: 10.2495/AFM180161

M. Elkhoury, Amina Elcheik

{"title":"SCALE-RESOLVING SIMULATION OF FLOW THROUGH A PERIODIC ARRAY OF CUBES","authors":"M. Elkhoury, Amina Elcheik","doi":"10.2495/AFM180161","DOIUrl":"https://doi.org/10.2495/AFM180161","url":null,"abstract":"Previous Scale-Resolving Simulation studies of flow over urban-like obstacles uses Large Eddy Simulation and course grids to reduce computational cost. However, the coarser the mesh the more reliance on the subgrid scale model to accurately account for scales associated with high wavenumbers. Furthermore, when high-resolution simulations are of importance, such as the transport of urban contaminants, mesh refinement becomes necessary. Often clustering of mesh cells produce errors at grid-refinement interfaces, mainly on the fine side of the mesh when it is located upstream of the coarse one. Three scale-resolving turbulence models, the One-Equation Scale-Adaptive Simulation (One-Eq.SAS), the Shear Stress Transport-Improved Delayed Detached Eddy Simulation (SST-IDDES), and the Algebraic Wall-Modelled Large Eddy Simulation (WMLES) models are utilized to assess their effect on the accuracy of the results when applied on both coarse and mesh-refined grids. The selection of these models was first based on the computational cost where the WMLES is the cheapest to solve since it involves no partial differential equation, while the SST-IDDES model is computationally the most expensive. Simulations are carried out on a relevant and complex test case of flow through a periodic array of cubes. The results reveal that models that do not inherent grid scale parameters in their formulation perform best in flows with global instabilities.","PeriodicalId":261351,"journal":{"name":"Advances in Fluid Mechanics XII","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131085726","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: 3

A REVIEW OF MODELLING APPROACHES FOR FLOW AND HEAT TRANSFER IN NANOFLUIDS 纳米流体流动和传热建模方法综述

Advances in Fluid Mechanics XII Pub Date : 2018-07-10 DOI: 10.2495/AFM180021

J. Ravnik, J. Tibaut

引用次数: 0

A STUDY OF IN-LINE TYPE SUBSEA SEPARATOR FOR MULTIPHASE FLOW OF OIL AND GAS WELLS 油气井多相流直列式水下分离器的研究

Advances in Fluid Mechanics XII Pub Date : 2018-07-10 DOI: 10.2495/AFM180121

Young-Ju Kim, N. Woo, Sangmok Han, Hyunji Kim, Kyu-Hyun Lee, J. Shon, Jae-Won Lee

{"title":"A STUDY OF IN-LINE TYPE SUBSEA SEPARATOR FOR MULTIPHASE FLOW OF OIL AND GAS WELLS","authors":"Young-Ju Kim, N. Woo, Sangmok Han, Hyunji Kim, Kyu-Hyun Lee, J. Shon, Jae-Won Lee","doi":"10.2495/AFM180121","DOIUrl":"https://doi.org/10.2495/AFM180121","url":null,"abstract":"The implementation of subsea separation and liquid boosting is becoming a common development scheme for the exploration of deep water fields. Subsea separation is an attractive and economic solution to develop deep offshore fields producing fluid without hydrate or wax. The subsea separation system should be reliable to ensure successful operation in a wide range of 3-phase flow regime, without the need for developments. A subsea separator can avoid or simplifying costly surface platforms of floating vessels, as well as being an efficient tool to enhance hydrocarbon production. One solution of interest is the separation and re-injection of water at the seabed to avoid bringing the water up to the surface facility. In this study, multiphase flow characteristics inside in-line type subsea separation systems are investigated for the design of a subsea separation system. The separation efficiency of the subsea separator is determined through experiments that are the liquid-gas phased separation. Also internal swirl element (ISE) modelling of the separator was optimized. The analysis results were utilized to improve the reliability and efficiency of the subsea separation system.","PeriodicalId":261351,"journal":{"name":"Advances in Fluid Mechanics XII","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133105805","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