The particle-in-cell method (PIC), especially the latest version of it, the material point method (MPM), has shown significant advantage over the pure Lagrangian method or the pure Eulerian method in numerical simulations of problems involving large deformations. It avoids the mesh distortion and tangling issues associated with Lagrangian methods and the advection errors associated with Eulerian methods. Its application to multiphase flows or multi-material deformations, however, encounters a numerical difficulty of satisfying continuity requirement due to the inconsistence of the interpolation schemes used for different phases. It is shown in Section 3 that current methods of enforcing this requirement either leads to erroneous results or can cause significant accumulation of errors. In the present paper, a different numerical method is introduced to ensure that the continuity requirement is satisfied with an error consistent with the discretization error and will not grow beyond that during the time advancement in the calculation. This method is independent of physical models. Its numerical implementation is quite similar to the common method used in Eulerian calculations of multiphase flows. Examples calculated using this method are presented. 相似文献
A solvent-driven micropump was developed using three-dimensional two-photon microfabrication. The actuation of micropump is
utilizing the bending behavior of hydrogel film under asymmetric solvent-stimulus. The micropump could absorb and discharge
fluid reversibly by simply alternating solvent composition. Contributing to the thin hydrogel film with the thickness of 2.5 μm,
the response time was significantly improved to 0.17 s. The discharge capacity of fluid was estimated to be as low as 9.2×10−2 pL. The pumping of such ultra-low-volume fluid will be useful for further miniaturization of micro-nanofluidic devices. 相似文献
A novel direct proportional pressure-regulating valve is presented in this paper, and its working principle is introduced. The pressure of feedback chamber is controlled by two orifices. The lumped parameter double-mass dynamic model considering both the spool mass and the plunger mass is established. The model consists of the subsystem models with hydraulic fluid dynamic, valve mechanic and electromagnetic. The numerical model is validated through experiments. With the model, the spool and pressure dynamics are analysed by comparing the changes of the simulation parameters. The effects of orifice diameters, lap, spring stiffness, viscous damping coefficient on the stability of spool and pressure are investigated. The results show that a fixed relationship between the orifice diameters of the valve can be achieved. A larger overlap is beneficial to improve the stability of the spool. It is aimed to propose a parametric design method for the valve optimization.
