Javed S. Shaikh^1,*, Krishna Kumar¹, Khizar A. Pathan², Sher A. Khan³

FDMP-Fluid Dynamics & Materials Processing, Vol.19, No.6, pp. 1637-1653, 2023, DOI:10.32604/fdmp.2023.025113

Abstract The complex fluid-dynamic instabilities and shock waves occurring along the surface of a two-dimensional wedge at high values of the Mach number are studied here through numerical solution of the governing equations. Moreover, a regression model is implemented to determine the pressure distribution for various Mach numbers and angles of incidence. The Mach number spans the interval from 1.5 to 12. The wedge angles (θ) are from 5° to 25°. The pressure ratio (P₂/P₁) is reported at various locations (x/L) along the 2D wedge. The results of the numerical simulations are compared with the regression model showing good agreement. More >

Da Li, Guodong Zhang, Ke Sun^*, Shuzhan Bai, Guoxiang Li^*

FDMP-Fluid Dynamics & Materials Processing, Vol.19, No.6, pp. 1479-1493, 2023, DOI:10.32604/fdmp.2023.022634

Abstract A dedicated heat exchanger model is introduced for the optimization of heavy-duty diesel engines. The model is a prerequisite for the execution of CFD simulations, which are used to improve waste heat recovery in these systems. Several optimization methods coupled with different types of working fluids are compared in terms of exergy efficiency and heat exchanger complicity. The three considered optimization methods all lead to significant improvements in the R245fa and R1233zd systems with a comparatively low evaporation temperature. The optimal R245fa system has the highest efficiency increase (77.49%). The cyclopentane system displays the highest effi- ciency among the optimized… More >

W. M. Faizal^1,*, C. Y. Khor¹, Muhammad Nooramin Che Yaakob¹, N. N. N. Ghazali², M. Z. Zainon², Norliza Binti Ibrahim³, Roziana Mohd Razi⁴

CMES-Computer Modeling in Engineering & Sciences, Vol.136, No.1, pp. 43-61, 2023, DOI:10.32604/cmes.2023.022716

Abstract This paper aims to investigate and present the numerical investigation of airflow characteristics using Turbulent Kinetic Energy (TKE) to characterize the upper airway with obstructive sleep apnea (OSA) under inhale and exhale breathing conditions. The importance of TKE under both breathing conditions is that it show an accurate method in expressing the severity of flow in sleep disorder. Computational fluid dynamics simulate the upper airway’s airflow via steady-state Reynolds-averaged Navier-Stokes (RANS) with k–ω shear stress transport (SST) turbulence model. The three-dimensional (3D) airway model is created based on the CT scan images of an actual patient, meshed with 1.29 million… More > Graphic Abstract

Xin Sun¹, Chi Zhang³, Yan Jia^1,2,*, Shikang Sui¹, Chong Zuo¹, Xueqiang Liu¹

Energy Engineering, Vol.120, No.3, pp. 729-742, 2023, DOI:10.32604/ee.2022.023398

Abstract As a part of the new energy development trend, distributed power generation may fully utilize a variety of decentralized energy sources. Buildings close to the installation location, besides, may have a considerable impact on the wind turbines’ operation. Using a combined vertical axis wind turbine with an S-shaped lift outer blade and Φ-shaped drag inner blade, this paper investigates how a novel type of upstream wall interacts with the incident wind at various speeds, the influence region of the turbulent vortex, and performance variation. The results demonstrate that the building’s turbulence affects the wind’s horizontal and vertical direction, as well… More > Graphic Abstract

Nur Husnina Muhamad Zuraidi¹, Sher Afghan Khan^1,*, Abdul Aabid^2,*, Muneer Baig², Istiyaq Mudassir Shaiq³

FDMP-Fluid Dynamics & Materials Processing, Vol.19, No.3, pp. 807-829, 2023, DOI:10.32604/fdmp.2023.023246

Abstract In this study, a duct is considered and special attention is paid to a passive method for the control of the base pressure relying on the use of a cavity with a variable aspect ratio. The Mach number considered is 1.8, and the area ratio of the duct is 2.56. In particular, two cavities are examined, their sizes being 3:3 and 6:3. The used L/D spans the interval 1–10 while the NPRs (nozzle pressure ratio) range from 2 to 9. The results show that the control becomes effective once the nozzles are correctly expanded or under-expanded. The pressure contours at… More >

Y. Nishio^1,*, B. Janssens¹, K. Limam², J. van Beeck³

FDMP-Fluid Dynamics & Materials Processing, Vol.19, No.3, pp. 743-753, 2023, DOI:10.32604/fdmp.2022.021848

Abstract A LES model is proposed to predict the dispersion of particles in the atmosphere in the context of Chemical, Biological, Radiological and Nuclear (CBRN) applications. The code relies on the Finite Element Method (FEM) for both the fluid and the dispersed solid phases. Starting from the Navier-Stokes equations and a general description of the FEM strategy, the Streamline Upwind Petrov-Galerkin (SUPG) method is formulated putting some emphasis on the related assembly matrix and stabilization coefficients. Then, the Variational Multiscale Method (VMS) is presented together with a detailed illustration of its algorithm and hierarchy of computational steps. It is demonstrated that… More >

Jun Feng^1,2, Tao Bian^1,2,5, Qianpeng Han², Bing Wang^1,3,4,*

FDMP-Fluid Dynamics & Materials Processing, Vol.19, No.1, pp. 1-14, 2023, DOI:10.32604/fdmp.2023.018275

Abstract The influence of the width of the circular ring of a car cooling fan on the aerodynamic noise is investigated numerically through the determination of the overall sound pressure level (OASPL). The results demonstrate that when the circular rings cover near 2/3 of the width of the blade tips of the rotor in the axis direction, the rotor has the lowest OASPL and the related total pressure efficiency and flow mass rate are better than the corresponding values obtained for a reference rotor without a circular ring. With increasing the width of the circular ring in the axis direction, the… More > Graphic Abstract

Jiacheng Qian¹, Chenqi Zou¹, Mengyan Zang^1,*, Shunhua Chen^2,3,*, Makoto Tsubokura⁴

CMES-Computer Modeling in Engineering & Sciences, Vol.133, No.2, pp. 251-280, 2022, DOI:10.32604/cmes.2022.020738

Abstract The stone chip resistance performance of automotive coatings has attracted increasing attention in academic and industrial communities. Even though traditional gravelometer tests can be used to evaluate stone chip resistance of automotive coatings, such experiment-based methods suffer from poor repeatability and high cost. The main purpose of this work is to develop a CFD-DEM-wear coupling method to accurately and efficiently simulate stone chip behavior of automotive coatings in a gravelometer test. To achieve this end, an approach coupling an unresolved computational fluid dynamics (CFD) method and a discrete element method (DEM) are employed to account for interactions between fluids and… More >

Khaled Said^*, Ahmed Ouadha, Amina Sabeur

FDMP-Fluid Dynamics & Materials Processing, Vol.18, No.6, pp. 1619-1629, 2022, DOI:10.32604/fdmp.2022.022220

Abstract The present study deals with double-diffusive convection within a two-dimensional inclined cavity filled with an air-CO₂ binary gas mixture. The left and the right vertical walls are differentially heated and subjected to different locations of (CO₂) contaminants to allow for the variation of the buoyancy strength (N). However, the horizontal walls are assumed adiabatic. The simulations are conducted using the finite volume method to solve the conservation equations of continuity, momentum, energy, and species transport. Good agreement with other numerical results in the literature is obtained. The effect of multiple parameters, namely, buoyancy ratio (N), thermal Rayleigh number (Ra), and… More >

Abdul Aabid^1,*, Sher Afghan Khan², Muneer Baig¹

FDMP-Fluid Dynamics & Materials Processing, Vol.18, No.6, pp. 1877-1900, 2022, DOI:10.32604/fdmp.2022.021860

Abstract A method based on microjets is implemented to control the flow properties in a convergent-divergent nozzle undergoing a sudden expansion. Three different variants of this active control technique are explored numerically by means of a finite-volume method for compressible fluid flow: with the first one, the control is implemented at the base, with the second at the wall, while the third one may be regarded as a combination of these. When jets are over-expanded, the control is not very effective. However, when a favourable pressure gradient is established in the nozzle, the control becomes effective, leading to an increase in… More >