N. Soltani¹, S. Rahal¹

FDMP-Fluid Dynamics & Materials Processing, Vol.13, No.1, pp. 1-17, 2017, DOI:10.3970/fdmp.2017.013.001

Abstract A three-dimensional time-dependent numerical study of the flow instabilities in a simulated Czochralski system is conducted. The comparison with previously published experimental results is reported. The simulations were performed using a refined grid in order to investigate flow instabilities in the crucible. Simulations have been carried out for various crystal rotational speeds, by taking into account the effects of Rayleigh and Marangoni numbers. The temperature fluctuations near the crystal/liquid interface are analyzed. The method used for that purpose is the Fast Fourier Transform with the corresponding spectra. From numerical simulations, it has been observed that More >

Seyed Milad Mirabedin^*

Frontiers in Heat and Mass Transfer, Vol.7, pp. 1-6, 2016, DOI:10.5098/hmt.7.17

Abstract This work focuses on numerical validation of natural convection heat transfer of TiO2-water nanofluids in a cylindrical container using COMSOL. The main aim of this study is to examine different available approaches to calculate effective thermal conductivity and compare them with experimental data available in the literature. Simulation results show that for considered mixture, average Nusselt number decreases by increasing Rayleigh number and particle volume fraction. It has been found that only one model was able to represent similar trends for given particle volume fractions, compared to experimental results. More >

Niki Rezazadeh, Rezvan Abdi^*

Frontiers in Heat and Mass Transfer, Vol.7, pp. 1-6, 2016, DOI:10.5098/hmt.7.30

Abstract This study investigates the heat transfer in the mode of natural convection from a pair of hot cylinders to a cold square enclosure. Effects of boundary conditions of the enclosure on the rate of heat transfer from a pair of isothermal hot cylinders are investigated at a Rayleigh number of 10⁵ . The cylinders are arranged in a horizontal array at the middle height of enclosure. The commercial software, Fluent (V.6.3.26), is utilized to solve the problem using the Finite Volume Method. The streamlines as well as isothermal lines of the problem are reported. Moreover, the More >

Xiaoqian Ma^a , Mo Yang^a,*, Yuwen Zhang^b

Frontiers in Heat and Mass Transfer, Vol.7, pp. 1-8, 2016, DOI:10.5098/hmt.7.36

Abstract Combustion mechanism of a 300 MW pulverized coal boiler is analyzed and the optimization of the performance of the boiler is carried out. The flow field, temperature field, devolatilization, char combustion and CO generation in the boiler furnace under actual condition is obtained by using Fluent. Three methods to improve the efficiency of boiler combustion are proposed based on the pulverized coal combustion mechanism; their feasibilities are verified through numerical simulation and analysis. The three proposed methods to increase the combustion efficiency may give theoretical reference for air arrangement and combustion optimization of the same More >

Dengfeng Su¹, Yong Kang^1,2,*, Xiaochuan Wang², andan Zheng¹, DongyangLi¹, Binyuan Yan¹, Fuwen Yan¹

CMES-Computer Modeling in Engineering & Sciences, Vol.111, No.5, pp. 375-393, 2016, DOI:10.3970/cmes.2016.111.375

Abstract Tunnel though coal seam is one of the most difficult tunnels since its risk of coal and gas outburst and the complex geological conditions. According to the directional cutting of water jet and the characteristic of the coal seam and rock mass, this paper presents a new method of tunnelling though coal seam assisted by water jet slotting, which can be divided into improving permeability of coal seam and directional cracking in the rock mass. The mechanism of improving permeability of coal seam was stated, and the crack criterion of rock during blasting was established… More >

Saber Hamimid¹, Messaoud Guellal²

FDMP-Fluid Dynamics & Materials Processing, Vol.12, No.4, pp. 137-153, 2016, DOI:10.32604/fdmp.2016.012.137

Abstract The numerical study of combined thermo-magnetic convection and surface radiation is presented in this paper and computations are performed for a paramagnetic fluid filled square cavity whose four walls have the same emissivity, placed in a micro-gravity environment (g ≈0), and subjected to various strong non-uniform magnetic field gradients. The vertical walls were isothermal, and the horizontal walls were adiabatic. Finite volume method based on the concepts of staggered grid and SIMPLER algorithm has been applied, and the view factors were determined by analytical formula. Representative results, illustrating the effect of magnetic field strength on More >

Zhuohuan Hu^a,*, Lulu Wang^a, Hui Wang^b, Mo Yang^a

Frontiers in Heat and Mass Transfer, Vol.6, pp. 1-8, 2015, DOI:10.5098/hmt.6.16

Abstract A numerical investigation was conducted to study the heat transfer in an aircraft cabin and the effects of air distribution under different angle and inlet velocity conditions. The Reynolds-averaged Navier–Stokes equations and the low Reynolds number turbulence model were used to simulate the airflow in the cabin. Mathematical statistics was used to process the relevant data, and statistical results revealed that different inlet angles and velocities significantly affect air temperature and flow field. The study also determined a set of optimum matching inlet vane angles and inlet velocities that result in an environment which meets More >

Hui Jiang^a,b, Daming Wu^a,b,c, Jian Zhuang^a,b,*, Ying Liu^a,b,c, Changqing Huang^a,b

Frontiers in Heat and Mass Transfer, Vol.6, pp. 1-6, 2015, DOI:10.5098/hmt.6.14

Abstract A new type of metal-plastic composite heat radiator with hemispherical microstructure array was proposed in this paper. The influence of the geometrical parameters of the microstructure array, including size of the hemisphere, configuration of hemisphere, tilt angle of the radiator, thermal conductivity and radiation emissivity of the plastic, on the process of heat transfer under natural convection were numerically simulated. It was concluded that the metal-plastic composite heat radiator with hemispherical microstructure array had comparable heat transfer behaviors with those of metal heat radiator. So it is possible to replace metal heat radiator by such More >

M. D. C. Magalhaes^1,2

CMES-Computer Modeling in Engineering & Sciences, Vol.105, No.6, pp. 441-465, 2015, DOI:10.3970/cmes.2015.105.441

Abstract The main goal of this study is to present an alternative and more efficient algorithm for a three-dimensional Component Mode Synthesis model to be used on sound transmission problems. The influence of fluid-structure interaction on airborne sound transmission problems is analysed using this model, which is based on simple volume geometries. In principle, the same procedure can also be applied when the component modes are obtained from alternative numerical techniques. The modal behaviour of acoustic volumes and a partition is implemented in two steps. The novelty of this alternative model is that the structural modes More >

Yiyu Lu¹, Chenpeng Song^1,2, Yunzhong Jia¹, Binwei Xia¹, Zhaolong Ge¹, Jiren Tang¹, Qian Li¹

CMES-Computer Modeling in Engineering & Sciences, Vol.105, No.1, pp. 69-86, 2015, DOI:10.3970/cmes.2015.105.069

Abstract In underground coal mines, hydrofracture can cause the increase of breathability in the fractured coal bed. When the hydrofracture crack propagates to the interface between the coal bed and the roof-floor stratum, the crack may enter roof-floor lithology, thus posing a limit on the scope of breathability increase and making it difficult to support the roof and floor board for subsequent coal mining. In this work, a two-dimensional model of coal rock bed that contains hydrofracture crack was constructed. Then an investigation that combines the fracture mechanics and the system of flow and solid in… More >