共查询到6条相似文献,搜索用时 15 毫秒
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The efficiency, robustness and reliability of recent numerical methods for finding solutions to flow problems have given rise to the implementation of computational fluid dynamics (CFD) as a broadly used analysis method for engineering problems like membrane separation system. The CFD modeling in this study observes steady and unsteady (transient) heat flux and temperature profiles in a polymeric (cellulose acetate) membrane. This study is novel due to the implementation of user defined scalar (UDS) diffusion equation by using user-defined functions (UDFs) infinite volume method (FVM). Some details of the FVM used by the solver are carefully discussed when implementing terms in the governing equation and boundary conditions (BC). The contours of temperature due to high-temperature gradient are reported for steady and unsteady problems. 相似文献
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A finite volume method (FVM) on distorted meshes for discretizing the energy equation's conduction term is presented. In this method, it is possible to compose the computational mesh of general quadrilateral elements (cells), namely, the cells are not required to be rectangular. The gradient of temperature on the cell's surface is computed to be second‐order accurate. Therefore, the error of numerical results by this method is smaller than using the traditional multilateral element method (MEM). The error does not depend on the degree of mesh distortion. The formulation based only on Taylor's theorem is straightforward. These are advantageous features to revise the fluid flow computation programs (based on FVM) that neglected the heat conduction term of the energy equation. The test calculations show that the convergence tendency of the numerical error using this method with the distorted mesh is the same as using an ordinary 2‐node central difference scheme on a constant‐interval rectangular mesh. By this method a conduction term was added to the energy equation of a SALE [ 1 ] program which had neglected that term originally, and z numerical calculation of a fluid flow with a heat transfer problem was performed. The numerical result of the present method with the distorted mesh well agrees with the analytical solution and the result of REM with a rectangular mesh. © 2011 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley Online Library ( wileyonlinelibrary.com/journal/htj ). DOI 10.1002/htj.20375 相似文献
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Application of high‐resolution NVD differencing schemes to the FTn finite volume method for radiative heat transfer 下载免费PDF全文
In this work, the STEP scheme and several schemes based on the normalized variable diagram (NVD), such as MINMOD, GAMMA, CLAM, NOTABLE, MUSCL, CUBISTA, SMART, WACEB, and VANOS schemes, are evaluated for solving the radiative transfer equation. Two‐dimensional and three‐dimensional rectangular enclosures containing transparent, emitting–absorbing, emitting–absorbing–scattering, or nonhomogeneous participating media are investigated using the modified FTn finite volume method. Although the NVD schemes are much more accurate than the STEP scheme, but they have more time‐consuming and require more iterations. Moreover, most of them often necessitate underrelaxation to ensure convergence. Results show that the MINMOD and GAMMA schemes are still much less accurate than other NVD schemes, but they converge the fastest of the NVD schemes, and do not require underrelaxation. Although the VANOS, WACEB, and SMART schemes give more accurate solutions, they are not competitive with other NVD schemes. However, the CLAM, NOTABLE, and CUBISTA schemes are relatively fast and accurate. 相似文献
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In the present work, element-free Galerkin method (EFGM) is modified and implemented to simulate thermoelastic fracture in functionally graded materials (FGMs). By solving the simple heat transfer problem, the temperature distribution over the domain can be obtained which is later used as an input to determine the displacement and stress fields. The crack surfaces are modeled under adiabatic and isothermal conditions. To capture stress fields around the crack tip, intrinsic enrichment criterion is used. A modified conservative M-integral technique has been used to extract the stress intensity factors (SIFs) for the simulated problems. A new algorithm to ensure equal number of nodes in support domain has been suggested. The optimum size of support domain is derived by performing an optimization of predefined EFGM parameters, namely, total number of nodes in problem geometry, Gauss quadrature, and number of nodes in support domain. Taguchi L-16 orthogonal array is used to obtain optimized values of these parameters. The results of analysis by optimized EFGM (OEFG) show about 80% reduction in computational time and an improvement in accuracy over EFGM. The present analysis shows that the results obtained by OEFG are in good agreement with those available in the literature. 相似文献
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《International Journal of Hydrogen Energy》2022,47(51):21803-21816
In this paper a dynamic membrane electrode assembly water transport model, based on the Finite Volume Method, is presented. The purpose of this paper is to provide an accessible and reproductible model capable of real time simulation. To this aim, a detailed explanation is provided regarding the equations and methods used to compute the physical-based fuel cell model. Additionally, the model is purposely developed using basic code (on Matlab?), to not be limited to a single programming language. Two phase water transport through multi-gaseous porous media (electrodes), interfacial transport, as well as diffusion, convection, and electro-osmosis within the polymer are considered. The main novelty relies in the restructuring of all equations into a single implicit system, which can iteratively be resolved through LU decomposition. This computationally efficient method allows the model to be capable of real-time simulation, by displaying the membrane water content profile evolution on a 3D figure. For nominal PEMFC operating conditions, a dry membrane reaches 35% of its final water concentration value after 2 s, and fully converges after 20 s. The final water content profile displays an 18% gradient (9 and 11 molecules per sulfonic acid sites on the anode and cathode sides, respectively). To calibrate and validate this model, mass transfer (flowmeter) and electrical (ohmmeter) methods have been applied. 相似文献