Shehab Khan Noor¹, Arif Mawardi Ismail¹, Mohd Najib Mohd Yasin^1,*, Mohamed Nasrun Osman¹, Nurulazlina Ramli², Ali H. Rambe³, J. Iqbal^4,5

CMC-Computers, Materials & Continua, Vol.74, No.1, pp. 2239-2259, 2023, DOI:10.32604/cmc.2023.031170 - 22 September 2022

Abstract This article presents the generation of Orbital Angular Momentum (OAM) vortex waves with mode 1 using Uniform Circular Array (UCA) antenna. Two different designs, namely, UCA-1 (4-element array antenna) and UCA-2 (8-element array antenna), were designed and fabricated using FR-4 substrate to generate OAM mode 1 at 3.5 GHz (5G mid-band). The proposed antenna arrays comprised rectangular microstrip patch elements with inset fed technique. The elements were excited by a carefully designed feeding phase shift network to provide similar output energy at output ports with desired phase shift value. The generated OAM waves were confirmed… More >

Alim Al Ayub Ahmed^1,*, Salim Oudah Mezan², Binyamin³, Murtadha Doghiam Abdullah⁴, Elena Tesleva⁵, Linar G. Akhmetov⁶, Rustem Zalilov⁷, Mustafa M. Kadhim^8,9,10, Abduladheem Turki Jalil^11,12

FDMP-Fluid Dynamics & Materials Processing, Vol.19, No.1, pp. 15-24, 2023, DOI:10.32604/fdmp.2022.019922 - 02 August 2022

Abstract The utilization of vortex generators to increase heat transfer from cylinders installed inside a duct is investigated. In particular, a channel containing eight cylinders with volumetric heat sources is considered for different values of the Reynolds number. The effective possibility to use vortex generators with different sizes to increase heat transfer and, consequently, reduce the surface temperature of the cylinders is examined. Also, the amount of pressure drop inside the channel due to the presence of vortex generators is considered and compared with the cases without vortex generators. The results show that although the addition More >

Hao Tian, Yongkang Zheng^*, Hanxin Zhang

FDMP-Fluid Dynamics & Materials Processing, Vol.19, No.1, pp. 207-222, 2023, DOI:10.32604/fdmp.2023.019790 - 02 August 2022

Abstract In this paper, some typical methods to promote mixing in supersonic combustion are reviewed, and the fluid-dynamic mechanism underpinning the development of the supersonic shear layer in the presence of a streamwise vortex is analyzed through computational fluid dynamics. It is proven that the streamwise vortex-couple method is an excellent approach to enhance mixing. A specific combustor design is proposed accordingly. More >

Amnart Boonloi^a, Withada Jedsadaratanachai^b,*

Frontiers in Heat and Mass Transfer, Vol.18, pp. 1-15, 2022, DOI:10.5098/hmt.18.20

Abstract Numerical analysis of fluid flow mechanism and heat transfer in a heat exchanger duct (HXD) with dual-inclined baffles (DIB) are reported. Three DIB types are examined: 1. “Type A” is located at the center of the HXD, 2. “Type B” is located on the upper-lower duct walls (as an orifice) and 3. “Type C” is a combination of the type A and B (as double orifices). The impacts of the ratio of DIB heights (b) to the square duct height (H; b/H) on increased heat transfer and friction loss are analyzed. Laminar flow (Re =… More >

Boonchai Lertnuwat

Frontiers in Heat and Mass Transfer, Vol.18, pp. 1-9, 2022, DOI:10.5098/hmt.18.1

Abstract The aim of this work is to numerically investigate the effect of mounting winglet vortex generators on different positions in rectangular-duct-type air heaters. The two investigated positions were the absorber plate and the insulation plate, opposite to the absorber plate. Four shapes of winglet vortex generator, i.e. perforated rectangular winglet vortex generators (P-RWVG), rectangular winglet vortex generators (RWVG), perforated trapezoidal winglet vortex generators (P-TWVG) and trapezoidal winglet vortex generators (TWVG), were used. Results showed that heat-transfer capability would be better if the winglet vortex generators were mounted on the opposite insulation plate in the cases More >

L. Cheng^a , Y. L. Zhang^a,† , J. F. Li^b

Frontiers in Heat and Mass Transfer, Vol.19, pp. 1-7, 2022, DOI:10.5098/hmt.19.32

Abstract The internal characteristics during rotational speed fluctuation have an important influence on centrifugal pump to avoid or utilize its transient performance. In this paper, a circulation piping system that includes a low-specific-speed centrifugal pump is established to study the energy distribution characteristics in a centrifugal pump during speed fluctuation. The unsteady flow in the entire system is numerically calculated with a user-defined function, the sliding grid method, and the RNG k-ε turbulence model. Then, the energy distribution of the transient flow field in the centrifugal pump model during speed fluctuation is diagnosed with vortex dynamics More >

A.C. Budiman^a,*, S. M. Hasheminejad^b, Sudirja^a, A. Mitayani^c, S. H. Winoto^d

Frontiers in Heat and Mass Transfer, Vol.19, pp. 1-6, 2022, DOI:10.5098/hmt.19.9

Abstract Streamwise development of counter-rotating vortices induced by three different types of chevron Vortex Generators (VGs) placed upstream an Electric Vehicles (EV) dummy battery module is experimentally visualized using a smoke-wire method. From the single chevron reference case, the mushroom-like vortices do not collapse until passing the module. When more chevrons are used in line, the vortices become more prominent. It can also be observed that the vortex sizes and shapes are significantly influenced by the spanwise base length of the chevron. The induced vortices from all three VGs suggest a potential heat transfer augmentation for More >

Weijun Pan^*, Jingkai Wang, Hao Wang, Yuming Luo

FDMP-Fluid Dynamics & Materials Processing, Vol.18, No.5, pp. 1495-1509, 2022, DOI:10.32604/fdmp.2022.019018 - 27 May 2022

Abstract A model for the vortex distribution in the wake of an aircraft is elaborated to investigate the wake influence on the behaviour of other aircrafts potentially interacting with it. As a realistic case, the interaction of an ARJ21 aircraft with a (leading) A330-200 aircraft is considered. Different distances are considered, namely, 6 km, 7 km, 8 km, 9.3 km, and 10 km. Simulations based on the used wake dissipation mechanism are used to investigate different conditions, namely, the ARJ21 in take-off and level flight and the changes induced in the related lift by the front More > Graphic Abstract

Guanni Qu^1,#, Tianai Yue^2,#,*, Xiaoyu Zhang³, Shibiao Wei³

FDMP-Fluid Dynamics & Materials Processing, Vol.18, No.3, pp. 591-608, 2022, DOI:10.32604/fdmp.2022.017776 - 22 February 2022

Abstract The present study stems from the realization that the general problem relating to the analysis of wind-induced vibrations in suspension bridges still requires significant attention. Sidewalk railings, overhaul tracks, and deflectors are known to largely affect such dynamics. Here, the influence of a row of water-filled traffic barriers on the response of a sample suspension bridge is investigated numerically. It is shown that the existence of water barriers causes flow separation and non-negligible vortices with respect to the condition with no water barriers. The vortex shedding frequency at the far end is around 41.30 Hz, More >

Jiawei Shi¹, Shuai Ge¹, Xiaozhen Sheng^2,*

FDMP-Fluid Dynamics & Materials Processing, Vol.18, No.2, pp. 463-480, 2022, DOI:10.32604/fdmp.2022.017508 - 16 December 2021

Abstract In order to understand the mechanism by which a pantograph can generate aerodynamic noise and grasp its far-field characteristics, a simplified double-strip pantograph is analyzed numerically. Firstly, the unsteady flow field around the pantograph is simulated in the frame of a large eddy simulation (LES) technique. Then the location of the main noise source is determined using surface fluctuating pressure data and the vortex structures in the pantograph flow field are analyzed by means of the Q-criterion. Based on this, the relationship between the wake vortex and the intensity of the aerodynamic sound source on… More >