Huihui Zhai¹, Dongqi Jiao², Haichao Zhou^2,*

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 >

Amer A. Abdulrahman¹, Bashar J. Kadhim¹, Zainab Y. Shnain¹, Hassan Sh. Majidi², Asawer A. Alwaiti^1,*, Farooq Al-Sheikh¹, Adnan A. AbdulRazak¹, Mohammed Shorbaz¹, Mazin J. Shibeeb³

FDMP-Fluid Dynamics & Materials Processing, Vol.19, No.10, pp. 2579-2595, 2023, DOI:10.32604/fdmp.2023.027454

Abstract The well-known frictional effect related to liquid-liquid two-phase flow in pipelines can be reduced using drag-reducing additives. In this study, such an effect has been investigated experimentally using a mixture of oil and water. Moreover, numerical simulations have been carried out using the COMSOL simulation software. The measurements were taken in a horizontal pipe with the length and diameter equal to 3 and 0.125 m, respectively. Moreover, Polyethylene oxide with 150 ppm was exploited to reduce the drag effect while considering different water-to-oil fractions (0.3, 0.4, 0.5, and 0.7) and a constant total flow velocity of 2.3 m/s. As made… More >

Wei Tian^a , Mingjun Pang^a,*, Na Xu^b,†

Frontiers in Heat and Mass Transfer, Vol.16, pp. 1-12, 2021, DOI:10.5098/hmt.16.13

Abstract Drag reduction (DR) by the additive of mixed surfactant and polymer is investigated in detail in a rotating disk apparatus (RDA). Polyethylene oxide (PEO) and Cetyltrimethyl ammonium chloride (CTAC)/sodium salicylate (NaSal) are chosen as polymer and surfactant, respectively. It is investigated on the influence of combination concentration of polymer & surfactant, temperature and Reynolds number on the drag-reducing rate. The present experimental results show that the drag-reducing rate of the mixed solution is definitely higher than that of the pure PEO or CTAC/NaSal solutions. This phenomenon is especially sharp at the high temperature and/or the large Reynolds number. When the… More >

Lanqi Chen, Yuwei Wang, Cong Qi^*, Zhibo Tang, Zhen Tian

FDMP-Fluid Dynamics & Materials Processing, Vol.18, No.5, pp. 1205-1227, 2022, DOI:10.32604/fdmp.2022.021200

Abstract Nowadays, the utilization rate of electronic products is increasing while showing no obvious sign of reaching a limit. To solve the associated “internal heat generation problem”, scientists have proposed two methods or strategies. The first approach consists of replacing the heat exchange medium with a nanofluid. However, the high surface energy of the nanoparticles makes them prone to accumulate along the heat transfer surface. The second method follows a different approach. It tries to modify the surface structure of the electronic components in order to reduce the fluid-dynamic drag and improve the rate of heat exchange. This article reviews these… More > Graphic Abstract

Mingjun Du^1,2, Jiaqiang Jing^1,*, Xinqiang Xiong³, Bingbing Lang², Xuan Wang², Shiying Shi^4,*

FDMP-Fluid Dynamics & Materials Processing, Vol.18, No.1, pp. 81-91, 2022, DOI:10.32604/fdmp.2022.016640

Abstract Transportation of heavy oil by the so-called water-ring technique is a very promising method by which pressure drop and pollution can be significantly reduced. Dedicated experiments have been carried out by changing the phase’s density, viscosity, velocity and interfacial tension to systematically analyze the characteristics of the water ring. On the basis of such experimental data, a mathematical model for pressure drop prediction has been introduced. This research shows that as long as the density of oil and water remains the same, a concentric water ring can effectively be formed. In such conditions, the oil-water viscosity difference has little effect… More >

Jiawei Jiang, Yizhou Shen^*, Jie Tao^*, Zhenfeng Jia, Xinyu Xie, Chaojiao Zeng

Journal of Renewable Materials, Vol.10, No.3, pp. 781-797, 2022, DOI:10.32604/jrm.2022.017230

Abstract A new type of microstructure inspired by the cross section of barchan dunes was proposed to reduce windage, which was considered as a passive drag reduction technology in aerospace manufacturing field. Computational fluid dynamics method was carried out to discuss the effect of the microstructure on the skin friction reduction under high velocity flow condition. Different microstructure heights were employed to survey the reduction of drag. The results illustrated that the appearance of microstructure led to a generation of pressure drag in non-smooth model (with microstructures inspired by cross section of barchan dune) in contrast to smooth model. However, the… More > Graphic Abstract

Zihai Geng^1,2,*, Jinsheng Cai¹, Yubiao Jiang^1,2, Weiguo Zhang^1,2

FDMP-Fluid Dynamics & Materials Processing, Vol.17, No.5, pp. 899-915, 2021, DOI:10.32604/fdmp.2021.012108

Abstract Reducing drag during take-off and nominal (cruise) conditions is a problem of fundamental importance in aeronautical engineering. Existing studies have demonstrated that v-shaped symmetrical riblets can effectively be used for turbulence control, with those with dimensionless depth h⁺ = 15 and dimensionless width s⁺ = 15 having the best drag reduction effect. In the present study, experimental tests have been conducted considering two models of the same size, one with smooth surface, the other with v-shaped riblets of the h⁺ = 15 and s⁺ = 15 type. The results show that for an angle of attack in the 8°~20° range… More >

Jingfa Li¹, Bo Yu^1,*, Qianqian Shao², Dongliang Sun¹

CMES-Computer Modeling in Engineering & Sciences, Vol.125, No.2, pp. 541-563, 2020, DOI:10.32604/cmes.2020.011835

Abstract In this work, the drag-reducing mechanism of high-Reynoldsnumber turbulent channel flow with surfactant additives is investigated by using large eddy simulation (LES) method. An N-parallel finitely extensible nonlinear elastic model with Peterlin’s approximation (FENE-P) is used to describe the rheological behaviors of non-Newtonian fluid with surfactant. To close the filtered LES equations, a hybrid subgrid scale (SGS) model coupling the spatial filter and temporal filter is applied to compute the subgrid stress and other subfilter terms. The finite difference method and projection algorithm are adopted to solve the LES governing equations. To validate the correctness of our LES method and… More >

Hayder A. Abdulbari ^1,2, Hassan D. Mahammed¹, Z. Hassan, Wafaa K. Mahmood³

FDMP-Fluid Dynamics & Materials Processing, Vol.12, No.2, pp. 86-101, 2016, DOI:10.3970/fdmp.2016.012.086

Abstract An experimental investigation was carried out to study the response of a turbulent pressure drop fluctuations to longitudinal groove riblets, involved two configurations being triangular and spaced triangular grooves with height 600, 800, 1000 μm and peak to peak spacing 1000 μm and 2000 μm respectively. Experiments were therefore performed at free stream velocity up to 0.44 m/sec, which were corresponding to Reynolds number (Re) 53000. The development of the obtained turbulent layer downstream of the grooves was then compared with the results from the corresponding smooth-wall case. To conclude, the effect of the spaced triangular riblets on the turbulent… More >