The animation shows the dynamic analysis of a simplified piping system, similar to those used in nuclear power plants. The analysis is performed using the ADINA subsonic potential-based fluid elements to model the water in the pipe and the ADINA 4-node shell elements (MITC4 elements) to model the pipe walls.
The animation is a simulation of the flow field when one car passes another in a tunnel. The simulation demonstrates the use of the sliding mesh interface feature, which will be available in version 8.2 of ADINA.
Narrow gaps are present in rotating and reciprocating machinery such as turbines, compressors, pistons, and gear pumps. These narrow gaps are often essential for the operation of the machinery, as leakage of the working fluid through the narrow gap provides lubrication between the moving parts, and these narrow gaps frequently are moving. Narrow gaps can also be used in the computational fluid model although not seen in the physical problem. This occurs in models with solid-to-solid contact. For example, consider the reed valve shown in Figure 1. Reed valves are a type of check valve that restrict flow to a single direction, opening and closing under changing pressure on each face. When the reed valve is open, fluid flows from the inlet port to the top chamber. When the reed valve is closed, solid-to-solid contact between the reed valve and the inlet port seat prevents flow. (a)Reed valve is open. Fluid flows from the inlet port to the top chamber. (b) Reed valve is closed. There is no fluid flow. Figure 1 Fluid flow through a reed valve In the analysis of a reed valve, see here for an example of a piston with a suction reed valve, fluid elements must
In a previous Brief, we presented some structural analysis results of the superconducting coil of the Wendelstein 7-X, the world’s largest plasma fusion experimental device of the stellarator family.
Each time a neutrophil (cell) pass through the human lungs, it typically crosses over 50 capillary segments. The transit time of the neutrophil depends on its deformability, surface tension, pressure drop across the capillary, and the geometry of the capillary.
In civil engineering design and analysis, the effects of fluids on the motion of structures can be very important. This is particularly true in seismic analysis of liquid storage tanks. In this class of problems, the fluid and tank motions are not large, and the viscosity of the fluid usually can be neglected. The important fluid characteristics that need to be included are the fluid density and compressibility, the bulk fluid motions and the pressures transmitted to the structure (both static and dynamic). For these problems, the potential-based fluid elements of ADINA are the most efficient way to model the fluid. The elements have only one degree of freedom per node, the fluid potential degree of freedom. Keeping the number of degrees of freedom down is crucial, because the model of the tank structure itself can be large. The potential-based fluid formulation is linear. Therefore, when the potential-based fluid elements are included, they do not cause any additional convergence problems. Figure 1: Fluid-filled tank using Potential-Based Fluid Elements in ADINA Some analysis experiences on these problems have been obtained by SC Solutions for ExxonMobil’s proprietary modular LNG storage tank, which was subjected to an earthquake. The results below are shown
The ADINA-TMC (Thermo-Mechanical Coupling) program is a powerful tool for fully coupled thermo-mechanical analysis of problems in which the thermal solution affects the structural solution and the structural solution in turn affects the thermal solution. ADINA-TMC takes into account such effects as the internal heat generation due to plastic deformations of the material, heat transfer between contacting bodies, and surface heat generation due to friction on the contacting surfaces.
The above animation depicts an axisymmetric model of a mono-tube gas shock absorber, with its schematic beside it. The piston inside the casing pushes its way through the oil (the hydraulic fluid which in reality is a mixture of oil and gas) creating resistance as the oil is pushed through the small holes in the piston. The contact between the piston (solid model) and the casing is modeled by specifying a friction coefficient, which is usually very small due to the lubrication provided by the oil. The spring is initially extended and then released. Its subsequent motion is damped by the oil flowing through the holes in the piston. The figure below shows the acceleration of the piston during a 0.2-second damping event.
FSI (fluid-structure interaction) analysis has many applications in the automotive industry such as the analysis of shock absorbers and valve mechanisms. In the ADINA System, the ADINA-FSI program provides fully coupled analysis of fluid flow with structural interaction problems, meeting the needs of automotive and other industries.