Hasnain Kashif^*, Muhammad Nasir Khan

CMC-Computers, Materials & Continua, Vol.73, No.3, pp. 6001-6017, 2022, DOI:10.32604/cmc.2022.031291 - 28 July 2022

Abstract Recently, free space optical (FSO) communication is gaining much attention towards the research community. The reason for this attention is the promises of high data-rate, license-free deployment, and non-interfering links. It can, however, give rise to major system difficulties concerning alignment and atmospheric turbulence. FSO is the degradation in the signal quality because of atmospheric channel impairments and conditions. The worst effect is due to fog particles. Though, Radio Frequency (RF) links are able to transmit the data in foggy conditions but not in rain. To overcome these issues related to both the FSO and… More >

Georgie Crewdson, Marcello Lappa^*

FDMP-Fluid Dynamics & Materials Processing, Vol.18, No.3, pp. 497-510, 2022, DOI:10.32604/fdmp.2022.020248 - 22 February 2022

Abstract The ability to control the distribution of particles in a fluid is generally regarded as a factor of great importance in a variety of fields (manufacturing processes, biomedical applications, materials engineering and various particle separation processes, to cite a few). The present study considers the hitherto not yet addressed situation in which solid spherical particles are dispersed in a non-isothermal fluid undergoing turbulent vibrationally-induced convection (chaotic thermovibrational flow in a square cavity due to vibrations perpendicular to the imposed temperature difference). Although the possibility to use laminar thermovibrational flows (in microgravity) and turbulent flows of More >

O. M. Oyewola^a,b,*, O. S. Ismail^b, J. O. Bosomo^b

Frontiers in Heat and Mass Transfer, Vol.17, pp. 1-5, 2021, DOI:10.5098/hmt.17.8

Abstract This paper investigates possible inherent modifications of the radiative heat source term due to the influence of turbulence in the thermal radiation field of a gas turbine combustor flame. Adapting a flame temperature of 2000[K], COMSOL Multiphysics software was utilized to numerically simulate the process, assuming a gray gas participating medium with absorption coefficient of 0.03[m^-1]. The analysis of the results for five (5) different radial cut sections of the simulated combustor chamber shows that turbulence-radiation interactions cause radiative heat losses from the flame, with the divergence of the radiative heat flux having a deviation factor More >

Quanbin Ba^1,2, Yanbao Liu^1,2,*, Zhigang Zhang^1,2, Wei Xiong^1,2, Kai Shen^1,2

FDMP-Fluid Dynamics & Materials Processing, Vol.17, No.4, pp. 697-710, 2021, DOI:10.32604/fdmp.2021.014762 - 17 May 2021

Abstract The characteristics of the flow field associated with a multi-hole combined external rotary bit have been studied by means of numerical simulation in the framework of an RNG k-ε turbulence model, and compared with the results of dedicated rock breaking drilling experiments. The numerical results show that the nozzle velocity and dynamic pressure of the nozzle decrease with an increase in the jet distance, and the axial velocity of the nozzle decays regularly with an increase in the dimensionless jet distance. Moreover, the axial velocity related to the nozzle with inclination angle 20° and 30° can More >

Abdelkarim Hegab^*, Faisal Albatati, Mohammed Algarni

CMES-Computer Modeling in Engineering & Sciences, Vol.127, No.2, pp. 437-468, 2021, DOI:10.32604/cmes.2021.014690 - 19 April 2021

Abstract In this paper, analytical, computational, and experimental studies are integrated to examine unsteady acoustic/vorticity transport phenomena in a solid rocket motor chamber with end-wall disturbance and side-wall injection. Acoustic-fluid dynamic interactions across the chamber may generate intense unsteady vorticity with associated shear stresses. These stresses may cause scouring and, in turn, enhance the heat rate and erosional burning of solid propellant in a real rocket chamber. In this modelling, the unsteady propellant gasification is mimicked by steady-state flow disturbed by end-wall oscillations. The analytical approach is formulated using an asymptotic technique to reduce the full… More >

Yousuke Shimoda¹, Takahiro Matsumori¹, Kazuki Sato¹, Tatsuro Hirano¹, Naoya Fukushima^1,*

The International Conference on Computational & Experimental Engineering and Sciences, Vol.23, No.1, pp. 16-16, 2021, DOI:10.32604/icces.2021.08337

Abstract Along with rapid development of computer technologies, a wide range of turbulent flows have been investigated by direct numerical simulations and the big databases have been built throughout the world. From the DNS results, we can investigate turbulent characteristics in three-dimensional space and time. In the laboratory experiment, we can apply sophisticated laser diagnostics technique to measure flow field non-invasively in research. On actual equipment, it is very difficult to get the flow field data away from the wall. We can measure only wall information, such as wall shear stresses and pressure. When we predict… More >

Liang Ce, Yongchen Pan^*

FDMP-Fluid Dynamics & Materials Processing, Vol.16, No.6, pp. 1115-1128, 2020, DOI:10.32604/fdmp.2020.010829 - 17 December 2020

Abstract Two flow cases for scaled high speed train models with different length are numerically analyzed in the framework of the improved delayed detachededdy simulation model. Specific attention is paid to the shear flows and related mechanisms in the near turbulent wake created by these moving models. In particular, a comparative analysis is made on the distributions of turbulent kinetic energy (TKE) and turbulence production (TP) in planes perpendicular to the streamwise direction. The numerical results suggest that, in the wake region very close to the tail, significant TKE and TP can be ascribed to the More >

Chang Su^1,2, Qiangqiang Zheng^3,*, Wukun Zhao⁴

FDMP-Fluid Dynamics & Materials Processing, Vol.16, No.5, pp. 947-960, 2020, DOI:10.32604/fdmp.2020.09676 - 09 October 2020

Abstract In this research, the dynamics of wet spray nozzles with different geometries, used to accelerate shotcrete, are investigated on the basis of a suitable three-dimensional mathematical model and related numerical method. Simulations have been conducted in the frame of the SIMPLEC algorithm. The k-ε turbulence model has been used to account for turbulent effects. The study shows that when the angle of the convergent section is less than 3°, it has a scarce effect on the dynamics of the jet of shotcrete; with the increase of the convergence angle, the shotcrete jet velocity decreases and More >

Lijian Xu¹, Tianyang Yang², Lekang Yin³, Ye Kong², Yuri Vassilevski^4,5, Fuyou Liang^1,5,6,*

CMES-Computer Modeling in Engineering & Sciences, Vol.124, No.2, pp. 509-526, 2020, DOI:10.32604/cmes.2020.010719 - 20 July 2020

Abstract Computational modeling methods have been increasingly employed to quantify aortic hemodynamic parameters that are challenging to in vivo measurements but important for the diagnosis/treatment of aortic disease. Although the presence of turbulence-like behaviors of blood flow in normal or diseased aorta has long been confirmed, the majority of existing computational model studies adopted the laminar flow assumption (LFA) in the treatment of sub-grid flow variables. So far, it remains unclear whether LFA would significantly compromise the reliability of hemodynamic simulation. In the present study, we addressed the issue in the context of a specific aortopathy,… More >

Shengyang Feng^1,2,3,*, Dongbo Xiong⁴, Guojie Chen⁵, Yu Cui¹, Puxin Chen¹

FDMP-Fluid Dynamics & Materials Processing, Vol.16, No.3, pp. 651-663, 2020, DOI:10.32604/fdmp.2020.07981 - 25 May 2020

Abstract Convection and diffusion are the main factors affecting radon migration. In this paper, a coupled diffusion-convection radon migration model is presented taking into account turbulence effects. In particular, the migration of radon is simulated in the framework of the k-ε turbulence model. The model equations are solved in a complex 3D domain by the finite element method (FEM). Special attention is paid to the case study about radon migration in an abandoned air defense shelter (AADS). The results show that air convection in a confined space has a great influence on the radon migration and the More >