The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform
Celine Grandmont - One of the best experts on this subject based on the ideXlab platform.
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A projection algorithm for fluid-stucture interaction problems with strong added-Mass Effect
Comptes Rendus Mathématique, 2006Co-Authors: Miguel Angel Fernández, Jean-Frédéric Gerbeau, Celine GrandmontAbstract:This Note aims at introducing a semi-implicit coupling scheme for fluid-structure interaction problems with a strong added-Mass Effect. Our main idea relies on the splitting of added-Mass, viscous Effects and geometrical/convective non-linearities, through a Chorin-Temam projection scheme within the fluid. We state some theoretical stability results, in the linear case, and provide some numerical experiments. The main interest of the proposed scheme is its efficiency compared to the implicit approach.
P. Dabnichki - One of the best experts on this subject based on the ideXlab platform.
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Added Mass Effect on flapping foil
Engineering Analysis With Boundary Elements, 2012Co-Authors: Marco La Mantia, P. DabnichkiAbstract:Unsteady Effects caused by accelerating bodies in water play a very important role in biological propulsion. However, such propulsion mechanisms are challenging for simulation as both body geometry and locomotion patterns are quite complex and a natural first step is to model the motion of a standard man-made airfoil. The work presents simulations of harmonic oscillations of a NACA 0012 foil in water and the hydrodynamic forces generated were obtained by a Boundary Element Method (panel method) code. The focus is placed on one of the most important unsteady Effects, the added Mass Effect, which has not been sufficiently addressed in the literature. The corresponding unsteady forces were obtained through appropriately devised two-dimensional added Mass tensor. The computational results were compared to existing analytical ones and a maximum error of 10−6 was obtained for the added Mass coefficients of the circle of unit diameter. The development of a dedicated numerical approach for the calculation of the added Mass tensor is necessitated by the lack of analytical solution for a variety of wing shapes such as NACA foils. The simulations showed that for the range of investigated parameters the inertia thrust and lift generated by the flapping foil increase sharply when the added Mass contribution is considered. For example, if the Strouhal number is set to 0.3 and the ratio between the wing and fluid densities to 0.3, the time average of the inertia thrust increases by 23 times and the maximum of the inertia lift is ca. 37 times larger when the added Mass Effect is considered. Generally, a densities' ratio of order 1 results in an increase of the time-average inertia thrust of order 10. It was confirmed that, as the densities' ratio becomes larger, the contribution of the added Mass to the generated inertia forces decreased. As the Strouhal number increases, the added Mass Effect was found to be more dominant due to the imposed motion kinematics, i.e. the pitch amplitude. The obtained results show clearly that for the specific case of flapping flight in dense fluids the unsteady Effects caused by the object acceleration are of prime importance for two reasons: (i) accurate estimate of the generated thrust and (ii) realistic assessment of the resulting structural loads.
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Added Mass Effect on flapping foil
Engineering Analysis with Boundary Elements, 2012Co-Authors: Marco La Mantia, P. DabnichkiAbstract:Unsteady Effects caused by accelerating bodies in water play a very important role in biological propulsion. However, such propulsion mechanisms are challenging for simulation as both body geometry and locomotion patterns are quite complex and a natural first step is to model the motion of a standard man-made airfoil. The work presents simulations of harmonic oscillations of a NACA 0012 foil in water and the hydrodynamic forces generated were obtained by a Boundary Element Method (panel method) code. The focus is placed on one of the most important unsteady Effects, the added Mass Effect, which has not been sufficiently addressed in the literature. The corresponding unsteady forces were obtained through appropriately devised two-dimensional added Mass tensor. The computational results were compared to existing analytical ones and a maximum error of 10-6was obtained for the added Mass coefficients of the circle of unit diameter. The development of a dedicated numerical approach for the calculation of the added Mass tensor is necessitated by the lack of analytical solution for a variety of wing shapes such as NACA foils. The simulations showed that for the range of investigated parameters the inertia thrust and lift generated by the flapping foil increase sharply when the added Mass contribution is considered. For example, if the Strouhal number is set to 0.3 and the ratio between the wing and fluid densities to 0.3, the time average of the inertia thrust increases by 23 times and the maximum of the inertia lift is ca. 37 times larger when the added Mass Effect is considered. Generally, a densities ratio of order 1 results in an increase of the time-average inertia thrust of order 10. It was confirmed that, as the densities ratio becomes larger, the contribution of the added Mass to the generated inertia forces decreased. As the Strouhal number increases, the added Mass Effect was found to be more dominant due to the imposed motion kinematics, i.e. the pitch amplitude. The obtained results show clearly that for the specific case of flapping flight in dense fluids the unsteady Effects caused by the object acceleration are of prime importance for two reasons: (i) accurate estimate of the generated thrust and (ii) realistic assessment of the resulting structural loads. © 2011 Elsevier Ltd. ALl Rights Reserved.
Santosh Devasia - One of the best experts on this subject based on the ideXlab platform.
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Added-Mass Effect in Modeling of Cilia-Based Devices for Microfluidic Systems
Journal of Vibration and Acoustics, 2010Co-Authors: Jiradech Kongthon, B. Mckay, D. Iamratanakul, Kieseok Oh, Jae Hyun Chung, James J. Riley, Santosh DevasiaAbstract:This article shows that the added Mass due to fluid-structure interaction significantly affects the vibrational dynamics of cilia-based (vibrating cantilever-type) devices for handling microscale fluid flows. Commonly, the hydrodynamic interaction between the cilia-based actuators and fluid is modeled as a drag force that results in damping of the cilia motion. Our main contribution is to show that such damping Effects cannot explain the substantial reduction in the resonant-vibrational frequency of the cilia actuator operating in liquid when compared with the natural frequency of the cilia in air. It is shown that an added-Mass approach (that accounts for the inertial loading of the fluid) can explain this reduction in the resonant-vibrational frequency when operating cantilever-type devices in liquids. Additionally it is shown that the added-Mass Effect can explain why the cilia-vibration amplitude is not substantially reduced in a liquid by the hydrodynamic drag force. Thus, this article shows the need to model the added-Mass Effect, both theoretically and by using experimental results.
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Added-Mass Effect in Modeling of Cilia-Based Devices for Microfluidic Systems
ASME 2010 First Global Congress on NanoEngineering for Medicine and Biology, 2010Co-Authors: Jiradech Kongthon, B. Mckay, D. Iamratanakul, Kieseok Oh, Jae Hyun Chung, James J. Riley, Santosh DevasiaAbstract:This article shows that the added Mass due to fluid structure interaction significantly affects the vibrational dynamics of cilia-based devices. Our main contribution is to show that such damping Effects cannot explain the substantial reduction in the resonant vibrational frequency of the cilia operating in liquid when compared to the natural frequency of the cilia in air. It is shown that an added-Mass approach (that accounts for the inertial loading of the fluid) can explain this reduction in the resonant vibrational frequency when operating the cantilever-type devices in liquids. Additionally, it is shown that the added-Mass Effect can explain why the cilia-vibration amplitude is not substantially reduced in a liquid by the hydrodynamic drag force. Thus, this article shows the need to model the added-Mass Effect, both, theoretically and by using experimental results.Copyright © 2010 by ASME
Takashi Yamamoto - One of the best experts on this subject based on the ideXlab platform.
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DISCUSSION ON THE Mass Effect OF REBOUND HARDNESS THROUGH THE DEVELOPMENT OF THE SMALL BALL REBOUND HARDNESS TESTING MACHINE
2014Co-Authors: Takashi YamamotoAbstract:Rebound hardness is a popular onsite testing method to evaluate the hardness of heavy and Massive metal parts and products. However, such rebound testers are sometimes wrongly applied to small specimens that do not have enough Mass. In such a case, impact energy is partly “leaked” through the vibration of the specimen and this leads to a lowered and wrong value of the coefficient of restitution. This phenomenon is called a “Mass Effect,” and it is mainly caused by a heavy impact body mounted with a diamond or cemented carbide tip indenter.In 1987, Nakamura and Maki et al. developed a new rebound hardness tester to avoid the Mass Effect by using a small steel ball without an additional impact body. However, the testing direction is limited to upward only because launching a small ball in any direction was not easy at that time.In this paper, a prototype of a small ball rebound hardness tester(HNM-2012) in any direction was developed and the Mass Effect investigated and compared with conventional testers, using JIS Shore hardness standard blocks (φ64×t15mm, 380g). The advantage of a small ball rebound hardness tester is confirmed because no Mass Effect was observed for the tester, whereas conventional rebound testers showed a significant Mass Effect.
Eugenio Oñate - One of the best experts on this subject based on the ideXlab platform.
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Fluid–structure interaction problems with strong added‐Mass Effect
International Journal for Numerical Methods in Engineering, 2009Co-Authors: Sergio Idelsohn, Riccardo Rossi, Eugenio OñateAbstract:In this paper, the so-called added-Mass Effect is investigated from a different point of view of previous publications. The monolithic fluid–structure problem is partitioned using a static condensation of the velocity terms. Following this procedure the classical stabilized projection method for incompressible fluid flows is introduced. The procedure allows obtaining a new pressure segregated scheme for fluid–structure interaction problems, which has good convergent characteristics even for biomechanical application, where the added-Mass Effect is strong. The procedure reveals its power when it is shown that the same projection technique must be implemented in staggered FSI methods. Copyright © 2009 John Wiley & Sons, Ltd.
