In this paper, an efficient approximated method based upon the method of auxiliary sources （MAS） is proposed to solve the two-dimensional scattering problem of large, infinite dielectric cylinder. To reduce the size...In this paper, an efficient approximated method based upon the method of auxiliary sources （MAS） is proposed to solve the two-dimensional scattering problem of large, infinite dielectric cylinder. To reduce the size of the total computational cost, the formulation of the MAS is modified by minimizing the number of auxiliary sources considered to implement the solution. It is shown that the standard formulation of the method of auxiliary sources, based on placing a finite number of auxiliary sources in an interior cylinder and the same number in the exterior cylinder surrounding the physical boundary, can be replaced by a finite number of strips placed on the same interior and exterior cylinder. These strips, containing auxiliary sources, are separated by a constant angle. Thus, compared with the standard MAS, the number of auxiliary sources of the new approximated method is reduced; also the proposed method can greatly reduce the computational complexity and the memory requirement. The numerical results obtained in this paper reveal the validity of the proposed approximated method.展开更多
Convective heat transfer coefficient is one of the most vital parameters which reveals the thermal efficiency of a pipe flow.To obtain such coefficients for problems with variable pipe wall temperature,numerical itera...Convective heat transfer coefficient is one of the most vital parameters which reveals the thermal efficiency of a pipe flow.To obtain such coefficients for problems with variable pipe wall temperature,numerical iterative methods should be used which could be time-consuming and less accurate.In this paper,thermophysical properties of fluids are assumed to be constant.We define a variable related to the temperature gradient of the pipe wall and study the varying law of the local coefficient.Then,a sample-based scheme is proposed to avoid the calculation of a time-consuming problem in the use of solutions with low computing cost.To verify its accuracy,several problems in normal circle pipes with variable factors,such as the various temperatures of the pipe wall,the different radius of the pipe,and various velocities of fluid flow,are well resolved.Meanwhile,its validity in a convergent pipe is also studied.From the obtained results,the high accuracy and efficiency of the proposed scheme can be confirmed.Therefore,the proposed scheme for determining the convective heat transfer coefficient has great potential in engineering problems.展开更多
A lattice Boltzmann type pseudo-kinetic model for a non-homogeneous Helmholtz equation is derived in this paper. NumericM results for some model problems show the robustness and efficiency of this lattice Boltzmann ty...A lattice Boltzmann type pseudo-kinetic model for a non-homogeneous Helmholtz equation is derived in this paper. NumericM results for some model problems show the robustness and efficiency of this lattice Boltzmann type pseudo-kinetic scheme. The computation at each site is determined only by local parameters, and can be easily adapted to solve multiple scattering problems with many scatterers or wave propagation in nonhomogeneous medium without increasing the computational cost.展开更多
文摘In this paper, an efficient approximated method based upon the method of auxiliary sources （MAS） is proposed to solve the two-dimensional scattering problem of large, infinite dielectric cylinder. To reduce the size of the total computational cost, the formulation of the MAS is modified by minimizing the number of auxiliary sources considered to implement the solution. It is shown that the standard formulation of the method of auxiliary sources, based on placing a finite number of auxiliary sources in an interior cylinder and the same number in the exterior cylinder surrounding the physical boundary, can be replaced by a finite number of strips placed on the same interior and exterior cylinder. These strips, containing auxiliary sources, are separated by a constant angle. Thus, compared with the standard MAS, the number of auxiliary sources of the new approximated method is reduced; also the proposed method can greatly reduce the computational complexity and the memory requirement. The numerical results obtained in this paper reveal the validity of the proposed approximated method.
基金the National Natural Science Foundation of China(Grant No.12072103)the Fundamental Research Funds for the Central Universities(Grant No.B200202126)+2 种基金the Natural Science Foundation of Jiangsu Province(Grant No.BK20190073)the State Key Laboratory of Acoustics,Chinese Academy of Sciences(Grant No.SKLA202001)the China Postdoctoral Science Foundation(Grant Nos.2017M6I 1669 and 2018T110430).
文摘Convective heat transfer coefficient is one of the most vital parameters which reveals the thermal efficiency of a pipe flow.To obtain such coefficients for problems with variable pipe wall temperature,numerical iterative methods should be used which could be time-consuming and less accurate.In this paper,thermophysical properties of fluids are assumed to be constant.We define a variable related to the temperature gradient of the pipe wall and study the varying law of the local coefficient.Then,a sample-based scheme is proposed to avoid the calculation of a time-consuming problem in the use of solutions with low computing cost.To verify its accuracy,several problems in normal circle pipes with variable factors,such as the various temperatures of the pipe wall,the different radius of the pipe,and various velocities of fluid flow,are well resolved.Meanwhile,its validity in a convergent pipe is also studied.From the obtained results,the high accuracy and efficiency of the proposed scheme can be confirmed.Therefore,the proposed scheme for determining the convective heat transfer coefficient has great potential in engineering problems.
基金Project supported by the National Natural Science Foundation of China (Nos. 11171211, 11171212)the Fundamental Research Funds for the Central Universities
文摘A lattice Boltzmann type pseudo-kinetic model for a non-homogeneous Helmholtz equation is derived in this paper. NumericM results for some model problems show the robustness and efficiency of this lattice Boltzmann type pseudo-kinetic scheme. The computation at each site is determined only by local parameters, and can be easily adapted to solve multiple scattering problems with many scatterers or wave propagation in nonhomogeneous medium without increasing the computational cost.
