To improve the operational reliability of mixed flow pumps, the two-way coupling fluidstructureinteraction method is applied to investigate stresses and deformations of the impeller. The Reynolds-averaged Navier–Sto...
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To improve the operational reliability of mixed flow pumps, the two-way coupling fluidstructureinteraction method is applied to investigate stresses and deformations of the impeller. The Reynolds-averaged Navier–Stokes equation, coupled with the SST k-ω turbulent model, is solved in the fluid domain by using ANSYS CFX, while transient structure dynamics in the structural domain are calculated with the finite element method. The accuracy of the numerical results has been verified by experimental pump performance. The results show that the flow rate definitely has a noticeable effect on both deformations and stresses. With the flow rate increasing, the impeller deformation decreases, as well as the stress, which is completely different from centrifugal pumps, but similar to axial pumps. Moreover, a local maximum deformation occurs in the middle of blade inlet, and the maximum stress of the entire impeller fluctuates periodically. On the same shroud, the stress on the suction side is higher than the pressure side along the intersection path;and on the same side, the mean stress on the rear shroud is larger than the front shroud. This study can help understand the distribution of both deformations and stresses in the impeller and provide guidance for improving the operation safety of mixed flow pumps.
Although it might be believed that the eye only comprised a very small area of the face, its injury due to the ball impacts in different sports seems to be severe enough to entice many researchers to determine the lev...
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Although it might be believed that the eye only comprised a very small area of the face, its injury due to the ball impacts in different sports seems to be severe enough to entice many researchers to determine the level of injury and then attempt to minimize it. Sports-related eye injuries, especially tennis, pose a substantial and preventable problem to the eye due to the high speed of the tennis ball (69 m/s). This is why many ophthalmologists provide a wide range of information for their patients regarding the risks of eye injuries in tennis to prevent the injury to well over 100,000 eyes each year. However, so far although there are some general information regarding the injury to the human eye components due to the tennis ball impact, the details of the stresses and deformations have not been well determined. Therefore, the goal of this study was to determine the stresses and deformations of the eye components, including cornea, aqueous body, iris, ciliary body, lens, vitreous body, retina, sclera, optic nerve, extra and intraconal fats, and muscles, attributable to the tennis ball impact via a Lagrangian-Eulerian computational coupling model. Magnetic resonance imaging was employed to establish a finite element model of the human eye according to a normal human eye. The numerical results revealed the highest amount of stress in the iris (19.2 MPa), whereas the lowest one was observed in the vitreous body (1.77 Pa). The cornea also experienced the stress of 8.27 MPa which might be high enough to invoke rupture in this delicate material. In addition, the results exhibited a decreasing and increasing of the radius of curvature for the cornea and lens, respectively. Finally, the collision of the tennis ball to the eye triggered the resultant displacement of 0.045 A mu m in the optic nerve which may imply a non-significant injury to that. The findings of this study may have implications not only for understating the values of stresses and deformations in the human
Introduction: In spite the fact that a very small human body surface area is comprised by the eye, its wounds due to detonation have recently been dramatically amplified. Although many efforts have been devoted to mea...
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Introduction: In spite the fact that a very small human body surface area is comprised by the eye, its wounds due to detonation have recently been dramatically amplified. Although many efforts have been devoted to measure injury of the globe, there is still a lack of knowledge on the injury mechanism due to Primary Blast Wave (PBW). The goal of this study was to determine the stresses and deformations of the human eye components, including the cornea, aqueous, iris, ciliary body, lens, vitreous, retina, sclera, optic nerve, and muscles, attributed to PBW induced by trinitrotoluene (TNT) explosion via a Lagrangian-Eulerian computational coupling model. Materials and methods: Magnetic Resonance Imaging (MRI) was employed to establish a Finite Element (FE) model of the human eye according to a normal human eye. The solid components of the eye were modelled as Lagrangian mesh, while an explosive TNT, air domain, and aqueous were modelled using Arbitrary Lagrangian-Eulerian (ALE) mesh. Nonlinear dynamic FE simulations were accomplished using the explicit FE code, namely LS-DYNA. In order to simulate the blast wave generation, propagation, and interaction with the eye, the ALE formulation with Jones-Wilkins-Lee (JWL) equation defining the explosive material were employed. Results: The results revealed a peak stress of 135.70 kPa brought about by detonation upsurge on the cornea at the distance of 25 cm. The highest von Mises stresses were observed on the sclera (267.3 kPa), whereas the lowest one was seen on the vitreous body (0.002 kPa). The results also showed a relatively high resultant displacement for the macula as well as a high variation for the radius of curvature for the cornea and lens, which can result in both macular holes, optic nerve damage and, consequently, vision loss. Conclusion: These results may have implications not only for understanding the value of stresses and strains in the human eye components but also giving an outlook about the process of PBW
This study presents a numerical analysis of fluid-structure interaction, the structure of which is a flexible piezoelectric material. Piezoelectric materials are widely used in aero-elasticity and turbomachinery field...
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This study presents a numerical analysis of fluid-structure interaction, the structure of which is a flexible piezoelectric material. Piezoelectric materials are widely used in aero-elasticity and turbomachinery fields for vibration, flutter, and noise control. In this work, a FSI benchmark is revised to contain the piezoelectric materials. The influence of piezoelectricity on the oscillation of the structure and fluid flow is considered. For validation, two benchmark problems are solved and the results of the present code are compared with those of previous work. Current results show that the piezoelectric behavior of a plate significantly in fluences the oscillation of the plate and the fluid flow properties. (C) 2016 Sharif University of Technology. All rights reserved.
作者：
Chen, Colin XuRMIT
Sch Math & Geospatial Sci Melbourne Vic 3000 Australia
The article investigate how low-density lipoprotein (LDL) accumulation affects the plaque morphology during its growth, aiming to provide a better understanding of atherosclerosis development. It validates the 3-D 45 ...
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The article investigate how low-density lipoprotein (LDL) accumulation affects the plaque morphology during its growth, aiming to provide a better understanding of atherosclerosis development. It validates the 3-D 45 percent axis-symmetric stenosis model with plaque morphology of a bi-elliptical cross-sectional profile for numerical accuracy.
We consider an incompressible quasi-Newtonian fluid-structure interaction (FSI) problem formulated in a monolithic framework, where the matching conditions at the moving interface are satisfied. The fully discretized ...
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We consider an incompressible quasi-Newtonian fluid-structure interaction (FSI) problem formulated in a monolithic framework, where the matching conditions at the moving interface are satisfied. The fully discretized FSI system is discussed with detailed analysis for the stability and error estimate as well as numerical experiments that confirm the theoretical results. (C) 2015 Elsevier Ltd. All rights reserved.
In consideration of the problem that the effect of conduit structure on water hammer has been ignored in the classical theory,the Poisson coupling between the fluid and the pipeline was studied and a fourteen-equation...
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In consideration of the problem that the effect of conduit structure on water hammer has been ignored in the classical theory,the Poisson coupling between the fluid and the pipeline was studied and a fourteen-equation mathematical model of fluid-structure interaction(FSI)was ***,the transfer matrix method(TMM)was used to calculate the modal frequency,modal shape and frequency *** results were compared with that in experiment to verify the correctness of the TMM and the results show that the fluid-structure coupling has a greater impact on the modal frequencies than the modal ***,the influence on the response spectrum of different damping ratios was studied and the results show that the natural frequency under different damping ratios has changed little but there is a big difference for the pressure *** the decreasing of damping ratio,the damping of the system on frequency spectrum is more and more significant and the dispersion and dissipation is more and more *** the appropriate damping ratio should be selected to minimize the effects of the vibration of the *** results provide references for the theory research of FSI in the transient process.
Initiation and development of cardiovascular diseases can be highly correlated to specific biomechanical parameters. To examine and assess biomechanical parameters, numerical simulation of cardiovascular dynamics has ...
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ISBN:
(纸本)9781510600188
Initiation and development of cardiovascular diseases can be highly correlated to specific biomechanical parameters. To examine and assess biomechanical parameters, numerical simulation of cardiovascular dynamics has the potential to complement and enhance medical measurement and imaging techniques. As such, computational fluid dynamics (CFD) have shown to be suitable to evaluate blood velocity and pressure in scenarios, where vessel wall deformation plays a minor role. However, there is a need for further validation studies and the inclusion of vessel wall elasticity for morphologies being subject to large displacement. In this work, we consider a fluid-structure interaction (FSI) model including the full elasticity equation to take the deformability of aortic wall soft tissue into account. We present a numerical framework, in which either a CFD study can be performed for less deformable aortic segments or an FSI simulation for regions of large displacement such as the aortic root and arch. Both of the methods are validated by means of an aortic phantom experiment. The computational results are in good agreement with 2D phase-contrast magnetic resonance imaging (PC-MRI) velocity measurements as well as catheter-based pressure measurements. The FSI simulation shows a characteristic vessel compliance effect on the flow field induced by the elasticity of the vessel wall, which the CFD model is not capable of. The in vitro validated FSI simulation framework can enable the computation of complementary biomechanical parameters such as the stress distribution within the vessel wall.
Composite insulators will appear deformation under the strong wind, it makes serious stress concentration at the roots of the sheds. The roots of insulator sheds are in the state of stress fatigue under the cyclic win...
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ISBN:
(纸本)9781509004966
Composite insulators will appear deformation under the strong wind, it makes serious stress concentration at the roots of the sheds. The roots of insulator sheds are in the state of stress fatigue under the cyclic wind load, and finally lead to shed cracks. In allusion to the problems mentioned above, with the composite insulator for overhead contact system cantilever as the object, a model of 3D computer simulation was established. This paper discussed the relationship between deformation of the sheds and stress of the roots of insulator sheds, and explored the influence of wind speed, angle of wind approach and deformation of the sheds. The research shows that On the whole, the effect of the roots of the chamfering radius on the deformation is minimal, It is not important structural parameters of wind resistance. There is a linear relationship between wind speed, stress of the roots of sheds and deformation of the sheds. When the angle of wind approach is 17 degrees, the deformation of the sheds is biggest under same wind velocity. When the angle of wind approach is 84 degrees, the deformation of the sheds is smallest under same wind velocity. When the lower angle of the sheds is 7 degrees, the deformation of the sheds is smallest under same wind velocity. According to the above research results, the wind-resistant composite insulator is designed.
We consider an incompressible quasi-Newtonian fluid-structure interaction (FSI) problem formulated in a monolithic framework, where the matching conditions at the moving interface are satisfied. The fully discretized ...
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We consider an incompressible quasi-Newtonian fluid-structure interaction (FSI) problem formulated in a monolithic framework, where the matching conditions at the moving interface are satisfied. The fully discretized FSI system is discussed with detailed analysis for the stability and error estimate as well as numerical experiments that confirm the theoretical results. (C) 2015 Elsevier Ltd. All rights reserved.
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