Xingshi Wang

Connectivity-free front tracking method for multiphase flows with free surfaces

In this study, a connectivity-free front tracking method is developed to simulate multiphase flows with free surfaces. This method is based on the point-set method which does not require any connectivities between interfacial points to represent the interface. The main advantage of the connectivity-free approach is the easiness in re-constructing the interface when large topology change occurs. It requires an indicator field to be constructed first based on the existing interface and the surface curvature and normal are then computed using the indicator field. Here, we adopt the reproducing kernel particle method (RKPM) interpolation function that provides the ability to deal with free-surface flows and the flexibility of using non-uniform meshes when local fine resolution is needed. A points regeneration scheme is developed to construct smooth interfaces and to automatically handle topology changes. The mass conservation is verified by performing a single vortex advection test. Several 2-D and 3-D numerical tests including an oscillating droplet, dam-breaking, two droplet impacting and multi-bubble merging are presented to show the accuracy and the robustness of the method.

Fully-coupled aeroelastic simulation with fluid compressibility — For application to vocal fold vibration

In this study, a fully-coupled fluid-structure interaction model is developed for studying dynamic interactions between compressible fluid and aeroelastic structures. The technique is built based on the modified Immersed Finite Element Method (mIFEM), a robust numerical technique to simulate fluid-structure interactions that has capabilities to simulate high Reynolds number flows and handles large density disparities between the fluid and the solid. For accurate assessment of this intricate dynamic process between compressible fluid, such as air and aeroelastic structures, we included in the model the fluid compressibility in an isentropic process and a solid contact model. The accuracy of the compressible fluid solver is verified by examining acoustic wave propagations in a closed and an open duct, respectively. The fully-coupled fluid-structure interaction model is then used to simulate and analyze vocal folds vibrations using compressible air interacting with vocal folds that are represented as layered viscoelastic structures. Using physiological geometric and parametric setup, we are able to obtain a self-sustained vocal fold vibration with a constant inflow pressure. Parametric studies are also performed to study the effects of lung pressure and vocal fold tissue stiffness in vocal folds vibrations. All the case studies produce expected airflow behavior and a sustained vibration, which provide verification and confidence in our future studies of realistic acoustical studies of the phonation process.

Fully Coupled Fluid-Structure Interaction Simulations of Vocal Fold Vibration

The human vocal folds are modeled and simulated using a fully coupled fluid-structure interaction method. This numerical approach is efficient in simulating fluid and deformable structure interactions. The two domains are fully coupled using an interpolation scheme without expensive mesh updating or re-meshing. The method has been validated through rigorous convergence and accuracy tests. The response of the fluid affects the elastic structure deformation and vice versa. The goal of this study is to utilize this numerical tool to examine the entire fluid-structure system and predict the motion and vocal folds by providing constant inlet and outlet pressure. The input parameters and material properties, i.e. elastic and density of the vocal folds used in the model are physiological. In our numerical results, the glottal jet can be clearly identified; the corresponding pressure field distribution and velocity field are presented.© 2010 ASME

Fully‐coupled fluid‐structure interaction simulation of vocal folds.

In this talk, the human vocal folds are modeled and simulated using a fully‐coupled fluid‐structure interaction method. This numerical approach is efficient in simulating fluid and deformable structure interactions. The two domains are fully coupled using an interpolation scheme without expensive mesh updating or re‐meshing. The method has been validated through rigorous convergence and accuracy tests. The response of the fluid affects the elastic structure deformation and vice versa. The goal of this study is to utilize this numerical tool to examine the entire fluid‐structure system and predict the motion and vocal folds by providing constant inlet and outlet pressures. The input parameters and material properties, i.e., elastic and density of the vocal folds used in the model, are physiological. In our numerical results, the glottal jet can be clearly identified; the corresponding pressure field distribution and velocity field are presented.