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  • 1
    Electronic Resource
    Electronic Resource
    Numerical Simulation of Flows in a Pipe with an Aneurismal Sac (Effects of Aneurismal Models and Stents) (2008)
    s.l. ; Stafa-Zurich, Switzerland
    Advanced materials research Vol. 33-37 (Mar. 2008), p. 1025-1030 
    Details
    ISSN: 1662-8985
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Recently, the intravascular therapy using microcoils and stents to treat aneurysms hasattracted researcher’s interest. In this study, in order to evaluate the effects of the stents, a numericalsimulation of two-dimensional flows has been carried out for a pipe with a model of an aneurismalsac. Using aneurismal models with different inclined angles to the pipe, inflow conditions withsteady states or pulsations have been applied in the range of Reynolds number in human bloodflows. First, the computational results are compared with experiments under the steady inflowcondition, which has shown the reliability of the numerical simulation. Furthermore, the mechanismof flows with an aneurismal model is discussed in the case with or without a stent, and consequentlythe effect of the stent is clarified
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/40/transtech_doi~10.4028%252Fwww.scientific.net%252FAMR.33-37.1025.pdf
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    〈i〉In Vitro〈/i〉 Study on Branch Flows with a Cerebral Aneurysm (2008)
    s.l. ; Stafa-Zurich, Switzerland
    Advanced materials research Vol. 33-37 (Mar. 2008), p. 1037-1042 
    Details
    ISSN: 1662-8985
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The purpose of this study is to accumulate data to predict the ruptures of aneurysms on thebifurcation of the middle cerebral arteries at the base of the brain. Particular stress is laid onunderstanding the elemental nature of branch flows with/without an aneurysm. Therefore, “flowpatterns” and “wall shear stress”, which are important factors for the causes of ruptures, areinvestigated by the three-dimensional experiments in vitro and the two-dimensional numericalsimulations with simplified models. In the branch arteries without an aneurysm, there is a possibilityof growing aneurysms at the location slightly away from a stagnation point. If an aneurysm forms intoa centrosymmetric shape for the inlet axis, it is considered that they tend to grow further in asymmetrical plane. From the viewpoint of the risk of ruptures, recirculation flows becomeproblematic with the lower Reynolds number, while the influence of wall shear stress becomes largerwith the higher Reynolds number
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/40/transtech_doi~10.4028%252Fwww.scientific.net%252FAMR.33-37.1037.pdf
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Flowfield around a Body with Elastic Walls (2008)
    s.l. ; Stafa-Zurich, Switzerland
    Advanced materials research Vol. 33-37 (Mar. 2008), p. 1083-1088 
    Details
    ISSN: 1662-8985
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: When a bluff body is located in a uniform flow, the flow is separated and vortices areformed. Consequently, the vortices cause “flow-induced vibrations”. Especially, if the Strouhalnumber and the frequency of the body oscillation coincide with the natural frequency, the lock-inregime will occur and we could find the large damages on it. Therefore, it is profitable, in engineeringproblems, to clarify this phenomenon and to suppress the vibration, in which the effect of elastic wallson the suppression is focused. Then, the aims of this article are to clarify the oscillatory characteristicsof the elastic body and the flowfield around the body by numerical simulations, in which a squarepillar with elastic walls is set in a uniform flow. Two dimensional incompressible flows are solved bythe continuity equation, Navier-Stokes equation and the Poisson equation which are derived by takingdivergence of Navier-Stokes equation. Results show that a small deformation of elastic walls has alarge influence on the body motion. In particular, the effect is very distinct at the back
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/40/transtech_doi~10.4028%252Fwww.scientific.net%252FAMR.33-37.1083.pdf
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  • 4
    Electronic Resource
    Electronic Resource
    Study on Dynamic Characteristics of the 3-Dimensional Parachute-Like Body with Consideration of Virtual Mass (2008)
    s.l. ; Stafa-Zurich, Switzerland
    Advanced materials research Vol. 33-37 (Mar. 2008), p. 1221-1226 
    Details
    ISSN: 1662-8985
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: In this article the freely oscillating 3-dimensional parachute-like body sustained at onepoint is focused. To catch the real phenomenon by numerical simulation, the virtual mass isconsidered in this study. The flow field is calculated by using the MAC method applying third orderupwind scheme for the convex term, and applying central difference for the other terms. ALE methodis applied in order to consider a moving boundary problem. The virtual mass is calculated by using apotential flow at every time step. As a result, it has been made clear that the virtual mass has influenceon the freely oscillating rigid concave body motion. And the flow structure around the freelyoscillating parachute-like body is made clear
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/40/transtech_doi~10.4028%252Fwww.scientific.net%252FAMR.33-37.1221.pdf
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  • 5
    Electronic Resource
    Electronic Resource
    Numerical Study on Flow-Adaptive Stents (2008)
    s.l. ; Stafa-Zurich, Switzerland
    Advanced materials research Vol. 33-37 (Mar. 2008), p. 1031-1036 
    Details
    ISSN: 1662-8985
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Recently for the treatment of aneurysms, endovascular therapy with microcoils and stentshas started. This study explores the design of better stents by means of numerical computations fromthe viewpoint of the fluid mechanics. Two-dimensional flows are numerically solved for a stentedduct with a model of an aneurysmal sac by changing the distribution of stent filaments under theconstraint of a constant porosity for the neck. Stents are assessed by whether the wall shear stress(WSS) on the aneurismal wall and the shear rate (SR) within the aneurysm are made lower.Barometers for the allocation of filaments are sought, and resultant optimized stents are those wherefilament(s) should be attached to both the distal and proximal wall of the neck, with more filaments tothe distal wall, to make the WSS low, and filaments should be appropriately distributed in the off-wallportion of the neck to make the SR low
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/40/transtech_doi~10.4028%252Fwww.scientific.net%252FAMR.33-37.1031.pdf
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  • 6
    Electronic Resource
    Electronic Resource
    On TVD difference schemes for the three-dimensional Euler equations in general co-ordinates (1989)
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 9 (1989), S. 1011-1024 
    Details
    ISSN: 0271-2091
    Keywords: Inviscid flow ; TVD difference scheme ; Shock wave ; Expansion wave ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: An improved treatment for the Harten-Yee and Chakravarthy-Osher TVD numerical flux functions in general co-ordinates is presented. The proposed formulation is demonstrated by a series of numerical experiments for three-dimensional flows around the ONERA-M6 wing. The numerical results indicate that it is important to use a suitable artificial compression parameter in order to obtain more accurate solutions around the leading edge of the wing. The two TVD numerical fluxes give excellent results: they capture the shock wave without numerical oscillations, they capture the rapid expansion around the leading edge sharply, they have self-adjusting mechanisms regarding numerical viscosity and they also have robustness.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/fld.1650090808
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