Papers by Keyword: Moving Mesh

Abstract: Theincrease of greenhouse gases emissions makes necessary to improve the comprehension of the Internal Combustion Engines operation. One of the factors that affect the combustion in these engines is the turbulence, since it can raise the quality of the fuel-air mixture inside the combustion chamber. However, when modeling internal combustion engines using CFD, the turbulence model choice is always a relevant problem. The present paper analyzes the results for three different turbulence models (k-ε Realizable, RNG k-ε and Menter k-ω SST) ina single-cylinder engine geometry, comparing numerical and experimental pressure data. For this experiment, the k-ε models obtained more trustable results than the k-ω SST, using less computational resources. The models achieved good results for eddy recirculation inside de cylinder and in regions of free shear flow at the valve openings, which makes possible to observe the correlation between parameters such as tumble and turbulent kinetic energy.

Abstract: the origins and characteristics of linear and nonlinear aeroelasticity are analyzed.And the deforming mesh , fluid-structure coupling schemes, the design method of aerodynamic module and structure module interface are also analyzed. their advantages and disadvantages are Pointed out. Finally, several recommendations are given for the development orientation of aeroelasticity in the future.

Abstract: A mathematic model based on moving mesh Arbitrary Lagrange-Eulerian (ALE) is developed to solve incompressible fluid flow concerned with the free surface and wettability. A mercury sessile drop with different wetting angles is chosen to validate this method. Besides, two more extensive applications called electrowetting-on-dielectric (EWOD) and transferred drop are numerically simulated and compared with previous researchers work in order to demonstrate its efficiency.

Abstract: For solving Laplace equation in 2D unbounded domains, a natural BEM on non-uniform grid is derived and its convergence theorem is proved. The moving mesh methods for the NBEM and the NBE-FE coupling method are also studied. Numerical results confirm the efficiency of the methods.

Abstract: The problem of free surface deformation is involved in variable fields ranging from material processing to metallurgy. In order to investigate the transient evolution of fluid field and free surface deformation numerically, three numerical simulation methods are proposed among which one is based on level set method, the other two are based on moving mesh method. Afterwards, a benchmark problem of sessile droplet is chosen to test and verify each numerical method. A comparison of each numerical result and experimental result shows a good agreement between each other. Comparison and discussion of three numerical methods are made in the end.

Abstract: In this study, moving mesh technique is used to construct an outside flow CFD model around H-vertical axis wind turbine with different types of airfoil. RNG turbulent models and the implicit Couple arithmetic based on pressure are selected to solve the transient equation. From the results of the calculation, the author obtains the velocity field, pressure field distribution of H-type vertical axis wind turbine airfoil at different moments and analyze the wind wheel blade torque variation. The conclusion provides the theoretical basis and a method to optimize aerodynamic performance for the further study of vertical axis wind turbine in the future.

Abstract: Three-dimensional computation of spray and combustion in 16V240ZJ diesel engine was performed by CFD numerical simulation tool FIRE. Because of the unceasing change of the temperature and the mixture in the cylinder, traditional performance-prediction method can only supply the limited information. The appearance of numerical simulation brought a bright future for the design and development of the new diesel engine. Combustion is an extremely complex process ,involving flow field, fuel injection and various combustion reactions. By calculus simulation, we have a thorough understanding of the combustion process of 16V240ZJ diesel engine. Through the flow field and concentrative analysis in the cylinder, the effect of advance angle of fuel on combustion process and formation of NOx and soot was investigated. The results show that the advance angle of fuel has a great effect on spray atomization and fuel-air mixture, and consequently influences the combustion and emission. By simulating , we can get the optimal advance angle of fuel for 16V240ZJ diesel engine is 15°BTDC, namely 345°CA, at which, the emissions are fewer ,and the efficiency is better .The CFD simulation has a direct value for optimizing the chamber’s structure and improving the combustion system.

Abstract: When vehicles run on road, they will be overtaken, cross by other vehicles or be impacted by crosswind. The other events of overtaking and in crosswind were investigated more deeply. A few of paper report the state of the research on this problem. Until now there are no any wind tunnel and road tests to study on road vehicle aerodynamics while crossing each other. Some numerical simulations were carried out by adopting technology of sliding interface and moving mesh. The method of numerical simulations was narrated in detail. The transient process of vehicles crossing each other was realized. Then the trends of aerodynamic coefficients changing were obtained from the flow field of simulation results. The quantificational changing of vehicles aerodynamic coefficients was obtained when they cross each other. The vehicles are sedan and coach. The simulation results indicated that the all aerodynamic coefficients of two vehicles changed large. The aerodynamic force was important to the vehicles’ handling stability when they cross each other.

Abstract: The use of composite materials in large structures has increased in recent years. Aircraft industry has recently begun to investigate the field of Liquid Composite Molding (LCM) through research programs because of its ability to produce large parts at low cost. The present paper focuses on modeling a 3D radial impregnation through an anisotropic fibrous perform. As a preliminary work, it is assumed an isothermal flow and no hydro-mechanical coupling. Governing equations are Darcy’s law and mass conservation. Simulation is performed combining Boundary Element Method (BEM) with a lagrangian moving mesh method. An analytical solution is developed to assess the numerical model.