Experimental verification of an Oseen flow slender body theory

Consider uniform flow past four slender bodies with elliptical cross-section of constant ellipticity along the length of 0, 0.125, 0.25 and 0.375, respectively, for each body. Here, ellipticity is defined as the ratio of the semiminor axis of the ellipse to the semimajor axis. The bodies have a pointed nose which gradually increases in cross-section with a radius of curvature 419mm to a mid-section which then remains constant up to a blunt end section with semimajor axis diameter 160 mm, the total length of all bodies being 800 mm. The bodies are side-mounted within a low-speed wind tunnel with an operational wind speed of the order 30ms−1. The side force (or lift) is measured within an angle of attack range of −3◦ to 3◦ such that the body is rotated about the major axis of the ellipse cross-section. The lift slope is determined for each body, and how it varies with ellipticity. It is found that this variance follows a straight line which steadily increases with increasing ellipticity. It is shown that this result is predicted by a recently developed Oseen flow slender body theory, and cannot be predicted by either inviscid flow slender body theory or viscous crossflow theories based upon the Allen and Perkins method

Application of the penalty coupling method for the analysis of blood vessels

Due to the significant health and economic impact of blood vessel diseases on modern society, its analysis is becoming of increasing importance for the medical sciences. The complexity of the vascular system, its dynamics and material characteristics all make it an ideal candidate for analysis through fluid structure interaction (FSI) simulations. FSI is a relatively new approach in numerical analysis and enables the multi-physical analysis of problems, yielding a higher accuracy of results than could be possible when using a single physics code to analyse the same category of problems. This paper introduces the concepts behind the Arbitrary Lagrangian Eulerian (ALE) formulation using the penalty coupling method. It moves on to present a validation case and compares it to available simulation results from the literature using a different FSI method. Results were found to correspond well to the comparison case as well as basic theory

A review of composite structures subjected to dynamic loading

The following review of composite impact work summarises key research interests and provides a brief overview for the development of theoretical, experimental and numerical methods for low, high, and hyper velocity impact. Particular attention is given to experimental apparatus and techniques used for the different impact velocity regimes, and the implementation of failure criteria in finite element (FE) modelling methods which predict material behaviour. Areas are then identified for which limited research has been currently undertaken and suggestions are made for possible future research topics

Multiphysics Modelling of Powder Coating of U-Profiles: Towards Simulation-based Optimization of Key-Performance Attributes by Variation of Powder-Parameters

Multiphysics simulation software has been developed to predict the key performance attributes of industrial powder coating applications based on applied process-parameter settings. The software is a Eulerian-Lagrangian finite-volume Multiphysics solver based on OpenFOAM, capable of modelling mass transfer effects between powder-coating pistols and electrically grounded metallic substrates. It considers various factors such as fluid dynamics of process airflow, coating-particle dynamics, particle-substrate interactions, and particle charging mechanisms within the corona. The software is fully compatible with Massive Simultaneous Cloud Computing technology, allowing hundreds of simulated coating scenarios to be computed simultaneously. Experimental validation efforts have been conducted, indicating a high degree of practical relevance of the technology. The current simulation study aims to demonstrate the potential of the simulation software for adjusting coating lines and optimizing powder coating of U-profiles. Specifically, the study focuses on optimizing the key-performance-attributes of the powder coating application with respect to varying material parameters of the applied powder, namely mean particle diameter, standard deviation of Gaussian particle size distribution, and powder particle density. The software predicts and visualizes coating patterns, coating efficiencies, and the batch-based standard deviation of coating thickness on a U-shaped metallic substrate, resulting in concrete and optimized powder settings. The presented results and the applied software are highly relevant for powder material suppliers

A Qualitative Comparison of ANSYS and OpenFOAM results for Carbon dioxide Plume Transport

This research presents Computational Fluid Dynamics (CFD) simulations in ANSYS® illustrating emissions of to the air. The CFD simulations is employed to study plume transport in urban environment, i.e., Breivika port in the city of Tromsø. The case study presents a two-phase model considering specific wind strength and direction in the city of Tromsø. Geographical coordinates, temperature, and wind data were obtained from the open sources, such as Google Maps, and Norwegian Meteorological Institute. The results from the simulations indicates a potential outcome with respect to various weather conditions. It was revealed for vessels less than 30 meter chimney height, the higher the wind strength, the lower the plume dispersion, causing the plume to stay closer to the terrain. This brings in a concentrated amount of pollutants closer to the public areas. The terrain in the model is recognizable for the Tromsø port’s location. From the CFD results, it is illustrated that onshore wind with high wind strength could affect the environment. The results simulated in OpenFOAM are qualitatively showing the same as visible in ANSYS®

Selection of High Performance Alloy for Gas Turbine Blade Using Multiphysics Analysis

With the extensive increase in the utilization of energy resources in the modern era, the need of energy extraction from various resources has pronounced in recent years. Thus comprehensive efforts have been made around the globe in the technological development of turbo machines where means of energy extraction is energized fluids. This development led the aviation industry to power boost due to better performing engines. Meanwhile, the structural conformability requirements relative to the functional requirements have also increased with the advent of newer, better performing materials. Thus there is a need to study the material behavior and its usage with the idea of selecting the best possible material for its application. In this work a gas turbine blade of a small turbofan engine, where geometry and aerodynamic data was available, was analyzed for its structural behavior in the proposed mission envelope, where the engine turbine is subjected to high thermal, inertial and aerodynamic loads. Multiphysics Finite Element (FE) linear stress analysis was carried out on the turbine blade. The results revealed the upper limit of Ultimate Tensile Strength (UTS) for the blade. Based on the limiting factor, high performance alloys were selected from the literature. The two most recommended alloy categories for gas turbine blades are NIMONIC and INCONEL from where total of 21 types of INCONEL alloys and 12 of NIMONIC alloys, available on commercial bases, were analyzed individually to meet the structural requirements. After applying selection criteria, four alloys were finalized from NIMONIC and INCONEL alloys for further analysis. On the basis of stress-strain behavior of finalized alloys, the Multiphysics FE nonlinear stress analysis was then carried out for the selection of the individual alloy by imposing a restriction of Ultimate Factor of Safety (UFOS) of 1.33 and yield strength. Final selection is made keeping in view other factors like manufacturability and workability in due consideration

Finite element analysis of human femur bone

An effort is made to analyse the stresses experienced by the human femur. In order to achieve these results a CAD model was developed by using the 3-D scanning of generic human femur for an individual of 70 kg weight (approx. averaged adult weight). The marrow cavity has been approximated as a hollow cylinder. The FEM model was built using solid tetrahedral element (20-noded 186 structural solid, ANSYS®). The model was analysed for its sensitivity. The results were computed for the range of loads. In this analysis, the maximum stress and its location were noted. In addition, the critical value of load was estimated for ultimate failure (i.e. fracture). The evaluated results give an understanding of the natural safety factor. The presented results are of significant importance in replication of the natural design parameters in creating the synthetic bone substitutes

Quantitative analysis of accuracy of voidage computations in CFD-DEM simulations

CFD-DEM (Computational Fluid Dynamics-Discrete Element Modelling) is a two-phase flow numerical modelling technique, where the Eulerian method is used for the fluid and the Lagrangian method for the particles. The two phases are coupled by a fluid-particle interaction force (i.e. drag force) which is computed using a correlation. In a two-phase flow, one critical parameter is the voidage (or void fraction), which is defined as the ratio of the volume occupied by the fluid to the total volume. In a CFD-DEM simulation the local voidage is computed by calculating the volume of particles in a given fluid cell. For spherical particles, this computation is difficult when a particle is on the boundary of fluid cells. In this case, it is usual to compute the volume of a particle in a fluid cell approximately. One such approximation divides the volume of a particle into each cell in the same ratio as an equivalent cube of width equal to the particle diameter. Whilst this approach is computationally straight forward, the approximation introduces an error in the voidage computation. Here we estimate the error by comparing the approximate volume calculation with an exact (numerical) computation of the volume of a particle in a fluid cell. The results show that the error varies with the position of the particle relative to the cell boundary. A new approach is suggested which limits the error to less than 2.5 %, without significantly increasing the computational complexity

The Numerical Analysis and Experiment of Shock Processing for Bouef

When the shock wave processing is applied to food, it is understood to obtain the change in various physical properties. For instance, when hard beef is processed by the underwater shock wave, the tenderization of meat can be expected. In the future, it is a goal that the shock wave processor is spread in general as a home electrical appliance. In the design for the suitable pressure vessels for food processing, the phenomenon in pressure vessel are very complex in multi-physics manners. Therefore, in numerical calculation, a lot of parameter for the numerical analysis is need for pressure vessel material and various foods. In this study, we chose a beef as a sample of the food processing. First, we obtained an unknown parameter of the beef by measuring the front and the shock wave speed of the sample. Then, we will show some numerical results for shock loading of beef by using LS-DYNA3D. The experiments were carried out using the high-speed image converter camera, high-speed video camera and the explosive experimental facilities

Investigation of the radioprotective effect of arbutin on radiation-induced lung injury in rats: A histopathological study

Background: Radiaton-induced lung injury is a common complicaton after esophageal, breast, etc. cancer radiotherapy. We aimed to evaluate the radioprotectve effect of arbutn on acute radiaton-induced lung damage in male rats. Materials and Methods: Fifty-two male Wistar rats were divided into 4 groups: (i) control group (n = 10), (ii) vehicle group (n = 10, received distlled water intraperitoneally (ip)), (iii) X-irradiaton only (n=16, chest was irradiated to a single dose of 20 Gy x-rays) and (iv) arbutn + X-irradiaton (n=16, 75 mg/kg of arbutn 2 hours before irradiaton (ip), and then their chest was exposed to 20 Gy x-rays). For histopathological investgaton, 8 animals of each group were sacrificed 8 weeks after treatment and the rest of them were sacrificed 3 months after treatment. Results: The histopathological analysis in 8 weeks after X-irradiaton showed that there was a significant increase in inflammatory in X-irradiaton only group compared to control group. The administraton of arbutn 2 hours prior to X-irradiaton significantly reduced inflammaton and inflammatory factors such as macrophages, mast cell and neutrophil in arbutn + X-irradiaton group compared to X-irradiaton only group (P<0.05). The histopathologic investgaton performed 3 months after lung irradiaton indicated a significant reducton in fibrosis formaton in arbutn + X-irradiaton group compared to irradiaton only group (P<0.05). Localized chest X-irradiaton with 20 Gy caused histopathologic damage to the lungs for short-term. Conclusion: Arbutn has a great potental in reducing the histopathologic damage to lung tssue after thoracic irradiaton. © 2020 Novin Medical Radiation Institute. All rights reserved