Personal tools

Session 23

ALE Incompressible Fluid in LS-DYNA
The computation of fluid forces acting on a rigid or deformable structure constitutes a major problem in fluid- structure interaction. However, the majority of numerical tests consists in using two different codes to separately solve pressure of the fluid and structural displacements. In this paper, a monolithic with an ALE formulation approach is used to implicitly calculate the pressure of an incompressible fluid applied to the structure. The projection method proposed by Gresho is used to decouple the velocity and pressure
Incompressible CFD Results Using LS-DYNA. For High Reynolds Number Flow Around Bluff Bodies
This report will provide some insight on the new incompressible CFD solver that will be available in version 980 of LS-DYNA. Several test cases were performed by AS+ in order to evaluate the capabilities of these new solvers. These studies were conducted in cooperation with LSTC’s CFD developers. Among the various test cases, the airflow over the Ahmed body, a simplified car model will be presented. The flow around this body reproduces the basic aerodynamic features of cars on a well defined basic geometry in order to study the complex interactions associated with vortex wakes and boundary layer separation/reattachment zones. Results were compared to experimental data extracted from reference papers. The results shown here are all part of the global validation process of the incompressible CFD solver.
Development of Frequency Domain Dynamic and Acoustic Capabilities in LS-DYNA
A set of new features for frequency domain dynamic and acoustic computation have been implemented in LS- ® DYNA . They include random vibration and high-cycle fatigue analysis, frequency response functions, steady state dynamics, response spectrum analysis, and acoustic analysis based on boundary element methods or finite element ® methods. The objective of introducing these new features is to add capabilities to LS-DYNA to solve frequency domain vibration and noise radiation problems. This class of problems is very common in auto and aerospace industries and many other industries. The paper provides a brief introduction of the new features. Keywords for the features are introduced. Areas of applications are discussed. Some examples are given to illustrate how to use these features.
BEM Methods For acoustic and vibroacoustic problems in LS-DYNA
This paper presents the new developments of finite element methods and boundary element methods for solving vibro-acoustic problems in LS-DYNA. The formulation for a frequency domain finite element method based on Helmholtz equation is described and the solution for an example of a simplified compartment model is presented. For boundary element method, the theory basis is reviewed. A benchmark example of a plate is solved by boundary element method, Kirchhoff method and Rayleigh method and the results are compared. A dual boundary element method based on Burton-Miller formulation is developed for solving exterior acoustic problems which were bothered by the irregular frequency difficulty. Application of the boundary element method for performing panel contribution analysis is discussed. These acoustic finite element and boundary element methods have important application in automotive, naval and civil industries, and many other industries where noise control is a concern.