In this paper, an improved incompressible multi-relaxation-time lattice Boltzmann-front tracking approach is proposed to simulate two-phase flow with a sharp interface, where the surface tension is implemented. The la...In this paper, an improved incompressible multi-relaxation-time lattice Boltzmann-front tracking approach is proposed to simulate two-phase flow with a sharp interface, where the surface tension is implemented. The lattice Boltzmann method is used to simulate the incompressible flow with a stationary Eulerian grid, an additional moving Lagrangian grid is adopted to track explicitly the motion of the interface, and an indicator function is introduced to update the fluid properties accurately. The interface is represented by using a four-order Lagrange polynomial through fitting a set of discrete marker points, and then the surface tension is directly computed by using the normal vector and curvature of the interface. Two benchmark problems, including Laplace＇s law for a stationary bubble and the dispersion relation of the capillary wave between two fluids are conducted for validation. Excellent agreement is obtained between the numerical simulations and the theoretical results in the two cases.展开更多
In the process of missile large attack angle reentry,there exist nonlinear,strong coupling uncertainty and multi-input-multi-output(MIMO)in the movement equations,so the traditional small disturbance faces difficultie...In the process of missile large attack angle reentry,there exist nonlinear,strong coupling uncertainty and multi-input-multi-output(MIMO)in the movement equations,so the traditional small disturbance faces difficulties.For such situations,the method of feedback linearization is adopted to control the complex system,and the control method based on the fuzzy adaptive nonlinear dynamic inversion decoupling control of missile is proposed in the paper.According to the principle of time-scale separation,the system is separated into fast loop and slow loop,the method of dynamic inversion is applied to them,and the method of adaptive fuzzy approach is adopted to compensate for the uncertainty of the fast loop.The simulation results denote the control method in the paper has a better tracing characteristic and robustness.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.10872222 and 50921063)the Specialized Research Fund for the Doctoral Program of Higher Education of China(Grant No.20110191110037)the Fundamental Research Funds for the Central Universities,China(Grant Nos.CDJXS11240011 and CDJXS10241103)
文摘In this paper, an improved incompressible multi-relaxation-time lattice Boltzmann-front tracking approach is proposed to simulate two-phase flow with a sharp interface, where the surface tension is implemented. The lattice Boltzmann method is used to simulate the incompressible flow with a stationary Eulerian grid, an additional moving Lagrangian grid is adopted to track explicitly the motion of the interface, and an indicator function is introduced to update the fluid properties accurately. The interface is represented by using a four-order Lagrange polynomial through fitting a set of discrete marker points, and then the surface tension is directly computed by using the normal vector and curvature of the interface. Two benchmark problems, including Laplace＇s law for a stationary bubble and the dispersion relation of the capillary wave between two fluids are conducted for validation. Excellent agreement is obtained between the numerical simulations and the theoretical results in the two cases.
文摘In the process of missile large attack angle reentry,there exist nonlinear,strong coupling uncertainty and multi-input-multi-output(MIMO)in the movement equations,so the traditional small disturbance faces difficulties.For such situations,the method of feedback linearization is adopted to control the complex system,and the control method based on the fuzzy adaptive nonlinear dynamic inversion decoupling control of missile is proposed in the paper.According to the principle of time-scale separation,the system is separated into fast loop and slow loop,the method of dynamic inversion is applied to them,and the method of adaptive fuzzy approach is adopted to compensate for the uncertainty of the fast loop.The simulation results denote the control method in the paper has a better tracing characteristic and robustness.
