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  • Open Access

    ARTICLE

    Parametric Optimization of Wheel Spoke Structure for Drag Reduction of an Ahmed Body

    Huihui Zhai1, Dongqi Jiao2, Haichao Zhou2,*

    CMES-Computer Modeling in Engineering & Sciences, Vol.139, No.1, pp. 955-975, 2024, DOI:10.32604/cmes.2023.043322

    Abstract The wheels have a considerable influence on the aerodynamic properties and can contribute up to 25% of the total drag on modern vehicles. In this study, the effect of the wheel spoke structure on the aerodynamic performance of the isolated wheel is investigated. Subsequently, the 35° Ahmed body with an optimized spoke structure is used to analyze the flow behavior and the mechanism of drag reduction. The Fluent software is employed for this investigation, with an inlet velocity of 40 m/s. The accuracy of the numerical study is validated by comparing it with experimental results obtained from the classical Ahmed model.… More >

  • Open Access

    ARTICLE

    Simulation Method and Feature Analysis of Shutdown Pressure Evolution During Multi-Cluster Fracturing Stimulation

    Huaiyin He1, Longqing Zou1, Yanchao Li1, Yixuan Wang1, Junxiang Li1, Huan Wen1, Bei Chang1, Lijun Liu2,*

    Energy Engineering, Vol.121, No.1, pp. 111-123, 2024, DOI:10.32604/ee.2023.041010

    Abstract Multistage multi-cluster hydraulic fracturing has enabled the economic exploitation of shale reservoirs, but the interpretation of hydraulic fracture parameters is challenging. The pressure signals after pump shutdown are influenced by hydraulic fractures, which can reflect the geometric features of hydraulic fracture. The shutdown pressure can be used to interpret the hydraulic fracture parameters in a real-time and cost-effective manner. In this paper, a mathematical model for shutdown pressure evolution is developed considering the effects of wellbore friction, perforation friction and fluid loss in fractures. An efficient numerical simulation method is established by using the method of characteristics. Based on this… More >

  • Open Access

    ARTICLE

    Numerical Simulation of Surrounding Rock Deformation and Grouting Reinforcement of Cross-Fault Tunnel under Different Excavation Methods

    Duan Zhu1,2, Zhende Zhu1,2, Cong Zhang1,2,*, Lun Dai1,2, Baotian Wang1,2

    CMES-Computer Modeling in Engineering & Sciences, Vol.138, No.3, pp. 2445-2470, 2024, DOI:10.32604/cmes.2023.030847

    Abstract Tunnel construction is susceptible to accidents such as loosening, deformation, collapse, and water inrush, especially under complex geological conditions like dense fault areas. These accidents can cause instability and damage to the tunnel. As a result, it is essential to conduct research on tunnel construction and grouting reinforcement technology in fault fracture zones to address these issues and ensure the safety of tunnel excavation projects. This study utilized the Xianglushan cross-fault tunnel to conduct a comprehensive analysis on the construction, support, and reinforcement of a tunnel crossing a fault fracture zone using the three-dimensional finite element numerical method. The study… More >

  • Open Access

    ARTICLE

    DETERMINING HEAT TRANSFER COEFFICIENT OF HUMAN BODY

    A. Najjaran*, Ak. Najjaran, A. Fotoohabadi, A.R. Shiri

    Frontiers in Heat and Mass Transfer, Vol.4, No.1, pp. 1-5, 2013, DOI:10.5098/hmt.v4.1.3003

    Abstract In this paper, the aim is obtaining convection coefficient of human body. This field of study is essential in study of ventilation systems, astronauts’ clothes and any other fields in which human body is the main concern. At first a 3D human body has been designed by unstructured grids. Feet and hands are stretched completely in considered sample. Two postures (standing and supine) are considered for body. Soles and the back of entire body are considered in contact with the ground respectively in these postures. Other parts of human body are exposed to surrounding air. The heat transfer and the… More >

  • Open Access

    ARTICLE

    EX VIVO LIVER TISSUE RADIOFREQUENCY THERMAL ABLATION: IR MEASUREMENTS AND SIMULATIONS

    Edoardo Gino Macchi* , Giovanni Braschi, Mario Gallati

    Frontiers in Heat and Mass Transfer, Vol.5, pp. 1-8, 2014, DOI:10.5098/hmt.5.20

    Abstract Radiofrequency thermal ablation (RFTA) is a medical procedure currently widely adopted for liver tumors treatment. Its outcome is strongly influenced by temperature distribution near the RF applicator therefore continuous measurements are required both to validate RFTA numerical models and to better control the outcome of the procedure. The space-time evolution of the thermal field during RFTA on ex vivo porcine liver tissue has been measured by infrared thermal imaging in different experimental setups. A three-dimensional simulation of the whole experiment reproduces all the features of the thermal field measurements and validates the proposed measurement methodology. More >

  • Open Access

    ARTICLE

    NUMERICAL ANALYSIS OF NATURAL CONVECTION IN A RIGHTANGLED TRIANGULAR ENCLOSURE

    Manoj Kr. Triveni* , Dipak Sen, RajSekhar Panua

    Frontiers in Heat and Mass Transfer, Vol.5, pp. 1-8, 2014, DOI:10.5098/hmt.5.12

    Abstract A numerical investigation has been performed for heat transfer analysis in a right-angled triangular enclosure filled with water. The side wall of the enclosure is maintained at high temperature compare to the base wall while hypotenuse is kept thermally insulated. Two - dimensional steady-state continuity, momentum and energy equations along with the boussinesq approximation are solved by finite volume method using commercial available software, FLUENT 6.3. The computational results are shown in terms of isotherms, streamlines and velocity contour for Rayleigh number (105 ≤ Ra ≤ 107 ). The heat transfer is presented in terms of local and average Nusselt… More >

  • Open Access

    ARTICLE

    Numerical Study on the Effect of Vortex Generators on the Aerodynamic Drag of a High-Speed Train

    Tian Li1,2,*, Hao Liang1, Zerui Xiang2, Jiye Zhang1

    FDMP-Fluid Dynamics & Materials Processing, Vol.20, No.2, pp. 463-473, 2024, DOI:10.32604/fdmp.2023.043618

    Abstract A relatively high aerodynamic drag is an important factor that hinders the further acceleration of high-speed trains. Using the shear stress transport (SST) k-ω turbulence model, the effect of various vortex generator types on the aerodynamic characteristics of an ICE2 (Inter-city Electricity) train has been investigated. The results indicate that the vortex generators with wider triangle, trapezoid, and micro-ramp arranged on the surface of the tail car can significantly change the distribution of surface pressure and affect the vorticity intensity in the wake. This alteration effectively reduces the resistance of the tail car. Meanwhile, the micro-ramp vortex generator with its… More > Graphic Abstract

    Numerical Study on the Effect of Vortex Generators on the Aerodynamic Drag of a High-Speed Train

  • Open Access

    ARTICLE

    Numerical Simulation of Asphaltene Precipitation and Deposition during Natural Gas and CO2 Injection

    Shasha Feng*, Yi Liao, Weixin Liu, Jianwen Dai, Mingying Xie, Li Li

    FDMP-Fluid Dynamics & Materials Processing, Vol.20, No.2, pp. 275-292, 2024, DOI:10.32604/fdmp.2023.041825

    Abstract Asphaltene deposition is a significant problem during gas injection processes, as it can block the porous medium, the wellbore, and the involved facilities, significantly impacting reservoir productivity and ultimate oil recovery. Only a few studies have investigated the numerical modeling of this potential effect in porous media. This study focuses on asphaltene deposition due to natural gas and CO2 injection. Predictions of the effect of gas injection on asphaltene deposition behavior have been made using a 3D numerical simulation model. The results indicate that the injection of natural gas exacerbates asphaltene deposition, leading to a significant reduction in permeability near… More > Graphic Abstract

    Numerical Simulation of Asphaltene Precipitation and Deposition during Natural Gas and CO<sub>2</sub> Injection

  • Open Access

    ARTICLE

    Numerical Simulation of Slurry Diffusion in Fractured Rocks Considering a Time-Varying Viscosity

    Lei Zhu1,2, Bin Liu2, Xuewei Liu2,*, Wei Deng1, Wenjie Yao1, Ying Fan1

    FDMP-Fluid Dynamics & Materials Processing, Vol.20, No.2, pp. 401-427, 2024, DOI:10.32604/fdmp.2023.041444

    Abstract To analyze the effects of a time-varying viscosity on the penetration length of grouting, in this study cement slurries with varying water-cement ratios have been investigated using the Bingham’s fluid flow equation and a discrete element method. A fluid-solid coupling numerical model has been introduced accordingly, and its accuracy has been validated through comparison of theoretical and numerical solutions. For different fracture forms (a single fracture, a branch fracture, and a fracture network), the influence of the time-varying viscosity on the slurry length range has been investigated, considering the change in the fracture aperture. The results show that under different… More >

  • Open Access

    ARTICLE

    Numerical Analysis of the Influence of the Impinging Distance on the Scouring Efficiency of Submerged Jets

    Hao Chen1,2, Xianbin Teng2,*, Zhibin Zhang2, Faxin Zhu1, Jie Wang1, Zhaohao Zhang2

    FDMP-Fluid Dynamics & Materials Processing, Vol.20, No.2, pp. 429-445, 2024, DOI:10.32604/fdmp.2023.030585

    Abstract Water jet technology is widely used in submerged buried pipes as a non-traditional trenching process, often involving a complex sediment response. An important adjustable and influential engineering variable in this technology is represented by the impinging distance. In this study, the FLOW-3D software was used to simulate the jet scouring of sand beds in a submerged environment. In particular, four sets of experimental conditions were considered to discern the relationship between the maximum scour depth and mass and the impinging distance. As shown by the results, a critical impinging distance exists by which the static scour depth can be maximized;… More > Graphic Abstract

    Numerical Analysis of the Influence of the Impinging Distance on the Scouring Efficiency of Submerged Jets

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