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Gang Wang - One of the best experts on this subject based on the ideXlab platform.

  • numerical simulation of natural convection in an inclined porous cavity under time periodic Boundary Conditions with a partially active Thermal side wall
    RSC Advances, 2017
    Co-Authors: Feng Wu, Gang Wang
    Abstract:

    Natural convection in an inclined porous cavity with positively or negatively inclined angles is studied numerically for time-periodic Boundary Conditions on the left side wall and partially active Thermal Boundary Conditions on the right wall. The results show that a partially active Thermal Boundary Condition on wall B can lead to heat transfer between two opposing vertical side walls. Temperature locations on wall B have significant effects on heat transfer of wall B, but weak effects on that of wall A. Compared with the uniform Thermal boundaries, the non-uniform temperature distributions on wall B can reduce the oscillation amplitude of NuB. The absolute value of Nuav for the uniform Boundary Condition on wall B is highest when |φ| > 30° and the differences of Nuav between different Boundary Conditions on wall B decrease with the increasing of |φ|.

  • buoyancy induced convection in a porous cavity with sinusoidally and partially Thermally active sidewalls under local Thermal non equilibrium Condition
    International Communications in Heat and Mass Transfer, 2016
    Co-Authors: Feng Wu, Gang Wang, Wenjing Zhou
    Abstract:

    Abstract Steady non-Darcy natural convection in a porous cavity with non-uniform Thermal Boundary Condition is studied numerically by adopting the local Thermal non-equilibrium (LTNE) model in this paper. The top and bottom walls of the cavity are adiabatic. The left vertical wall is partially heated and cooled by sinusoidal temperature profile and the right side wall of the cavity is partially cooled by uniform Thermal Boundary Condition. The results show that, the oscillation amplitude of the local Nusselt number profiles (Nufy, Nusy) along the Y coordinate decreases with the increase of H. The difference of the local Nusselt numbers between different cases of partial cooling (case A–case D) can be reduced by increasing of N. The difference of solid-to-fluid temperature differences between different cases of partial cooling can be reduced by increasing of H and γ. Positive values of the average Nusselt number appear at the left side wall of the porous cavity, which indicates that there exists heat transfer along the positive direction of the X axis in the porous cavity. Compared with the left wall of the cavity, it is faster for the right wall to reach the Thermal equilibrium state, which approaches a constant value for low values of H (H = 3000).

  • numerical analysis of natural convection in a porous cavity with the sinusoidal Thermal Boundary Condition using a Thermal nonequilibrium model
    Numerical Heat Transfer Part A-applications, 2016
    Co-Authors: Gang Wang
    Abstract:

    ABSTRACTSteady non-Darcy natural convection in a porous cavity with sinusoidal Thermal Boundary Condition is studied numerically by adopting the local Thermal non-equilibrium (LTNE) model in this paper. The top and bottom walls of the enclosure are adiabatic, whereas the left vertical wall is partially heated and cooled by a sinusoidal temperature profile and the right vertical wall is cooled by the uniform Thermal Boundary Condition. The results show that, compared with the uniform Boundary Conditions, the sinusoidal Boundary Conditions can enhance the heat transfer rate of a porous cavity. The values of local Nusselt numbers at the left sidewall can be enhanced by sinusoidal Thermal Boundary Condition and the maximum absolute value of the local Nusselt number appears near the top and bottom walls of the cavity. The Thermal nonequilibrium effect on natural convection in the porous cavity can be enhanced by the sinusoidal Thermal Boundary Condition, and the absolute value of the dimensionless solid-to-flu...

  • numerical study of natural convection in a porous cavity with sinusoidal Thermal Boundary Condition
    Chemical Engineering & Technology, 2016
    Co-Authors: Gang Wang, Wenjing Zhou
    Abstract:

    The steady natural convection in a rectangular cavity filled with a heat-generating porous medium was numerically investigated using a Thermal non-equilibrium model for the heat transfer between the fluid and solid phases. All of the walls of the enclosure are adiabatic, except for the left wall, which is partially heated and cooled by a spatial sinusoidal temperature profile. The results show that the temperature fields near the left wall and the local Nusselt number of the left wall vary periodically because of the sinusoidal Boundary Condition. There exists an optimal fluctuant parameter of N (N = 3) to maximize the heat transfer rate of the fluid phase in the square enclosure. The periodicity parameter N has a significant influence on the value of the average Nusselt number of the fluid phase when the Darcy and Rayleigh numbers increase.

Wenjing Zhou - One of the best experts on this subject based on the ideXlab platform.

  • buoyancy induced convection in a porous cavity with sinusoidally and partially Thermally active sidewalls under local Thermal non equilibrium Condition
    International Communications in Heat and Mass Transfer, 2016
    Co-Authors: Feng Wu, Gang Wang, Wenjing Zhou
    Abstract:

    Abstract Steady non-Darcy natural convection in a porous cavity with non-uniform Thermal Boundary Condition is studied numerically by adopting the local Thermal non-equilibrium (LTNE) model in this paper. The top and bottom walls of the cavity are adiabatic. The left vertical wall is partially heated and cooled by sinusoidal temperature profile and the right side wall of the cavity is partially cooled by uniform Thermal Boundary Condition. The results show that, the oscillation amplitude of the local Nusselt number profiles (Nufy, Nusy) along the Y coordinate decreases with the increase of H. The difference of the local Nusselt numbers between different cases of partial cooling (case A–case D) can be reduced by increasing of N. The difference of solid-to-fluid temperature differences between different cases of partial cooling can be reduced by increasing of H and γ. Positive values of the average Nusselt number appear at the left side wall of the porous cavity, which indicates that there exists heat transfer along the positive direction of the X axis in the porous cavity. Compared with the left wall of the cavity, it is faster for the right wall to reach the Thermal equilibrium state, which approaches a constant value for low values of H (H = 3000).

  • numerical study of natural convection in a porous cavity with sinusoidal Thermal Boundary Condition
    Chemical Engineering & Technology, 2016
    Co-Authors: Gang Wang, Wenjing Zhou
    Abstract:

    The steady natural convection in a rectangular cavity filled with a heat-generating porous medium was numerically investigated using a Thermal non-equilibrium model for the heat transfer between the fluid and solid phases. All of the walls of the enclosure are adiabatic, except for the left wall, which is partially heated and cooled by a spatial sinusoidal temperature profile. The results show that the temperature fields near the left wall and the local Nusselt number of the left wall vary periodically because of the sinusoidal Boundary Condition. There exists an optimal fluctuant parameter of N (N = 3) to maximize the heat transfer rate of the fluid phase in the square enclosure. The periodicity parameter N has a significant influence on the value of the average Nusselt number of the fluid phase when the Darcy and Rayleigh numbers increase.

  • natural convection in a porous rectangular enclosure with sinusoidal temperature distributions on both side walls using a Thermal non equilibrium model
    International Journal of Heat and Mass Transfer, 2015
    Co-Authors: Wenjing Zhou
    Abstract:

    Abstract This study reports a numerical investigation of the natural convective flow and heat transfer in a rectangular cavity filled with a heat-generating porous medium by adopting the local Thermal non-equilibrium model. The top and bottom walls of the enclosure are adiabatic and the left and right walls are partially heated and partially cooled by sinusoidal temperature profile. The results show that periodic variations with positive and negative values appear in the isotherms for fluid phase and solid phase, and the periodicity increases with the increase of N. The phase deviation has significant influence on fluid flow and heat transfer in the porous cavity. When N is large enough (N = 32), patterns of streamlines, isotherms for fluid phase and solid phase display like that of uniform Thermal Boundary Condition case, and the total heat transfer rate through the whole cavity is close to that resulted by uniform Thermal Boundary Condition. The heat transfer of porous cavity can be enhanced by sinusoidal Thermal Boundary Condition and the phase deviation has tiny effect on the heat transfer of cavity when N is large enough (N = 32). The increase of inter-phase heat transfer coefficient leads to faster reduction of Q with the increase of periodicity parameter.

Shuangcheng Sun - One of the best experts on this subject based on the ideXlab platform.

  • Application of improved decentralized fuzzy inference methods for estimating the Thermal Boundary Condition of participating medium
    International Journal of Thermal Sciences, 2020
    Co-Authors: Shuangcheng Sun, Guangjun Wang, Hong Chen
    Abstract:

    Abstract The decentralized fuzzy inference method (DFIM) was applied to estimate the time-dependent heat flux of 1D participating medium. The direct problem concerned on coupled radiation and conduction heat transfer in the medium was solved by the finite volume method and discrete ordinate method. The simulated Boundary temperature was served as input for the inverse analysis. The inverse problem was formulated as an optimization approach. Three improved decentralized fuzzy inference methods (IDFIMs) were developed to accelerate the convergence rate and enhance the estimation accuracy. Five kinds of time-dependent heat fluxes were considered to test the performance of the present inverse technique. No prior information on the functional forms of the unknown Boundary Conditions was needed for the inverse analysis. All retrieval results showed that the incident heat flux of participating medium can be accurately estimated by DFIMs. The proposed IDFIMs achieved better performance than the original DFIM in terms of computational accuracy and efficiency. Moreover, a comparison between the IDFIM and other optimization techniques was conducted. The proposed IDFIM was proved to be more efficient and accurate than conjugate gradient method, Levenberg-Marquardt method, stochastic particle swarm optimization algorithm and genetic algorithm.

  • Simultaneous reconstruction of Thermal Boundary Condition and physical properties of participating medium
    International Journal of Thermal Sciences, 2026
    Co-Authors: Shuangcheng Sun
    Abstract:

    Abstract A hybrid optimization technique, which combines decentralized fuzzy inference method (DFIM) and sequential quadratic programming (SQP) algorithm, is developed to reconstruct the Thermal Boundary Condition and physical properties of participating medium simultaneously. The coupled radiation-conduction heat transfer in the medium is solved by finite volume method in combination with discrete ordinate method. The reconstruction task is formulated as an inverse problem which is solved by the hybrid DFIM-SQP technique from the knowledge of surface temperature and exit radiative intensity. Retrieval results demonstrate that the time-dependent heat flux, absorption coefficient, scattering coefficient and Thermal conductivity of participating medium can be accurately retrieved by the present methodology. The proposed DFIM-SQP technique is more accurate and efficient in solving the simultaneous reconstruction problem than DFIM, conjugate gradient method, SQP, particle swarm optimization and krill herd algorithms.

Hong Chen - One of the best experts on this subject based on the ideXlab platform.

  • Inverse determination of Thermal Boundary Condition and temperature distribution of workpiece during drilling process
    Measurement, 2021
    Co-Authors: Guangjun Wang, Hong Chen
    Abstract:

    Abstract For the problem that the moving Thermal Boundary Condition of workpiece is difficult to be measured directly in drilling process, an efficient estimation scheme is developed in this study. The proposed scheme takes into account the heat transfer characteristics of the drilling workpiece. Specifically, according to the moving Boundary position of workpiece, the heat transfer system of drilling workpiece is approximated by several linear subspaces. Correspondingly, the estimation results of unknown variable are obtained by comprehensively weighting the estimated results obtained from linear subspaces. Both numerical simulations and experimental tests are utilized to prove the validity of the above scheme. Effects of some important factors such as aperture size and measurement errors on the estimation results are discussed in detail. Comparisons with the traditional scheme are also carried out. The results obtained indicate that the presented approach can effectively estimate the moving Thermal Boundary Condition of workpiece, obviously reduce the calculation cost, and has good adaptive capability. This method can be used for online monitoring of the temperature distribution in drilling area, thereby ensuring the machining quality of the workpiece and the service life of the drilling tool.

  • Application of improved decentralized fuzzy inference methods for estimating the Thermal Boundary Condition of participating medium
    International Journal of Thermal Sciences, 2020
    Co-Authors: Shuangcheng Sun, Guangjun Wang, Hong Chen
    Abstract:

    Abstract The decentralized fuzzy inference method (DFIM) was applied to estimate the time-dependent heat flux of 1D participating medium. The direct problem concerned on coupled radiation and conduction heat transfer in the medium was solved by the finite volume method and discrete ordinate method. The simulated Boundary temperature was served as input for the inverse analysis. The inverse problem was formulated as an optimization approach. Three improved decentralized fuzzy inference methods (IDFIMs) were developed to accelerate the convergence rate and enhance the estimation accuracy. Five kinds of time-dependent heat fluxes were considered to test the performance of the present inverse technique. No prior information on the functional forms of the unknown Boundary Conditions was needed for the inverse analysis. All retrieval results showed that the incident heat flux of participating medium can be accurately estimated by DFIMs. The proposed IDFIMs achieved better performance than the original DFIM in terms of computational accuracy and efficiency. Moreover, a comparison between the IDFIM and other optimization techniques was conducted. The proposed IDFIM was proved to be more efficient and accurate than conjugate gradient method, Levenberg-Marquardt method, stochastic particle swarm optimization algorithm and genetic algorithm.

  • A double decentralized fuzzy inference method for estimating the time and space-dependent Thermal Boundary Condition
    International Journal of Heat and Mass Transfer, 2017
    Co-Authors: Guangjun Wang, Hong Chen, Shibin Wan, Daqian Zhang
    Abstract:

    Abstract For the inverse heat conduction problem to estimate the time and space-dependent Thermal Boundary Condition, a double decentralized fuzzy inference (DDFI) method with a temporal-spatial decoupling characteristic is proposed. A set of decentralized fuzzy inference modules (DFIMs) corresponding to the temperature measurement points are established. Each DFIM contains a set of decentralized fuzzy inference units (DFIUs), and each DFIM performs the fuzzy inference process from the vector of time series of temperature measurements at the corresponding temperature measurement points. The inference results of DFIUs in the time domain are weighed and synthesized by dynamic response coefficients to obtain the time adjustment vector of the Thermal Boundary Condition. In the space domain, the inference results of DFIMs are weighed and synthesized by the normal distribution function to obtain the space adjustment vector. Numerical experiments are performed to study the effects of the number of measurement points, measurement errors and the buried depth of thermocouples on the inversion results. Comparison with the existing dynamic matrix control inverse method is also conducted, and it shows the validity of the inverse method established in this paper.

Kwansoo Chung - One of the best experts on this subject based on the ideXlab platform.

  • numerical simulation of friction stir butt welding process for aa5083 h18 sheets
    European Journal of Mechanics A-solids, 2010
    Co-Authors: Harsha Badarinarayan, Kazutaka Okamoto, R H Wagoner, Kwansoo Chung
    Abstract:

    Abstract Thermo-mechanical simulation of the friction stir butt welding (FSBW) process was performed for AA5083-H18 sheets, utilizing a commercial finite volume method (FVM) code, STAR-CCM+, which is based on the Eulerian formulation. Distributions of temperature and strain rate histories were calculated under the steady state Condition and simulated temperature distributions (profiles and peak values) were compared with experiments. It was found that including proper Thermal Boundary Condition for the backing plate (anvil) is critical for accurate simulation results. Based on the simulation, Thermal and deformation histories of material elements were also calculated, useful to predict material characteristics of the weld such as hardness or grain size, and possibly for the susceptibility of weld to abnormal grain growth (AGG) after post-weld heat treatment.

  • numerical simulation of friction stir butt welding process for aa5083 h18 sheets
    European Journal of Mechanics A-solids, 2010
    Co-Authors: Dongun Kim, Harsha Badarinarayan, Kazutaka Okamoto, R H Wagoner, Ji Hoon Kim, Chongmin Kim, Kwansoo Chung
    Abstract:

    Abstract Thermo-mechanical simulation of the friction stir butt welding (FSBW) process was performed for AA5083-H18 sheets, utilizing a commercial finite volume method (FVM) code, STAR-CCM+, which is based on the Eulerian formulation. Distributions of temperature and strain rate histories were calculated under the steady state Condition and simulated temperature distributions (profiles and peak values) were compared with experiments. It was found that including proper Thermal Boundary Condition for the backing plate (anvil) is critical for accurate simulation results. Based on the simulation, Thermal and deformation histories of material elements were also calculated, useful to predict material characteristics of the weld such as hardness or grain size, and possibly for the susceptibility of weld to abnormal grain growth (AGG) after post-weld heat treatment.