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SERVICES WIKIS Author R Khare P Keblinski A Yethiraj Title Molecular Dynamics Simulations of Heat and Momentum Transfer at a Solid Fluid Interface Relationship between Thermal and Velocity Slip Year

Original URL path: http://www.scorec.rpi.edu/reports/view_report.php?id=431 (2015-07-15)

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presents a novel model reduction approach for periodic heterogeneous media which combines the multiple scale asymptotic MSA expansion method with the transformation eld analysis TFA to reduce the computational cost of a direct homogenization approach without signi cantly compromising on solution accuracy The evolution of failure in micro phases and interfaces is modeled using eigendeformation Adaptive model improvement strategy incorporating a hierarchical sequence of computational homogenization models is employed to

Original URL path: http://www.scorec.rpi.edu/reports/view_report.php?id=432 (2015-07-15)

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emanate from the heart and travel through the major arteries where they are damped dispersed and reflected due to changes in vessel caliber tissue properties and branch points As a consequence solutions to the governing equations of blood flow in the large arteries are highly dependent on the outflow boundary conditions imposed to represent the vascular bed downstream of the modeled domain The most common outflow boundary conditions for three dimensional simulations of blood flow are prescribed constant pressure or traction and prescribed velocity profiles However in many simulations the flow distribution and pressure field in the modeled domain are unknown and cannot be prescribed at the outflow boundaries An alternative approach is to couple the solution at the outflow boundaries of the modeled domain with lumped parameter or one dimensional models of the downstream domain We previously described a new approach to prescribe outflow boundary conditions for simulations of blood flow based on the Dirichlet to Neumann and variational multiscale methods This approach termed the coupled multidomain method was successfully applied to solve the non linear one dimensional equations of blood flow with a variety of models of the downstream domain This paper describes the extension of this method

Original URL path: http://www.scorec.rpi.edu/reports/view_report.php?id=433 (2015-07-15)

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The resulting expression for the filter width ratio is parameter free as difficult to compute filter widths required in earlier models are no longer necessary Traditionally the filter width ratio is taken as a constant based on assumptions which do not hold in general for all numerical discretizations Previous work has shown that simulation results may strongly depend on the filter width ratio parameter thus motivating its accurate determination The

Original URL path: http://www.scorec.rpi.edu/reports/view_report.php?id=434 (2015-07-15)

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11 Editor Science Direct Abstract Abstract Blood velocity and pressure fields in large arteries are greatly influenced by the deformability of the vessel Moreover wave propagation phenomena in the cardiovascular system can only be described considering wall deformability since blood is usually described as an incompressible fluid However computational methods for simulating blood flow in three dimensional models of arteries have either considered a rigid wall assumption for the vessel or significantly simplified or reduced geometries Computing blood flow in deformable domains using standard techniques like the ALE method remains a formidable problem for large realistic anatomic and physiologic models of the cardiovascular system We have developed a new method to simulate blood flow in three dimensional deformable models of arteries The method couples the equations of the deformation of the vessel wall at the variational level as a boundary condition for the fluid domain We consider a strong coupling of the degrees of freedom of the fluid and the solid domains and a linear membrane model enhanced with transverse shear for the vessel wall The effect of the vessel wall boundary is therefore added in a monolithic way to the fluid equations resulting in a remarkably robust scheme We

Original URL path: http://www.scorec.rpi.edu/reports/view_report.php?id=438 (2015-07-15)

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problem we developed a novel stabilized finite element method FEM employing a combination of ghost fluid and level set approaches This formulation treats both the air and water as compressible fluids Using this method a transient three dimensional 3 D solution was obtained for the implosion i e collapse and rebound of an air bubble These simulation results obtained were qualitatively similar to those observed predicted in previous experimental numerical studies The 3 D simulations show that the conditions within the bubble are nearly uniform until the converging pressure wave is strong enough to create very large temperatures and pressures near the center of the bubble These dynamics occur on very small spatial 0 1 0 7 lm and time ns scales The motion of the air water interface during the initial stages of the implosion was found to be consistent with predictions using a Rayleigh Plesset model However the simulations showed that during the final stage of energetic implosions the bubble can become asymmetric which is contrary to the spherical symmetry assumed in many previous numerical studies of bubble dynamics The direct numerical simulations predicted two different instabilities namely Rayleigh Taylor type interfacial surface and shape instabilities During the

Original URL path: http://www.scorec.rpi.edu/reports/view_report.php?id=439 (2015-07-15)

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sensitive to the choice of the basis functions employed in a numerical method and can be used with the finite volume or the finite element method on fully unstructured grids and meshes For a polynomial basis the dependence of the Smagorinsky length scale on the order of completeness of the basis functions and the degree of anisotropy of the grid is examined It is found that the length scale decreases

Original URL path: http://www.scorec.rpi.edu/reports/view_report.php?id=440 (2015-07-15)

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the craft s temporal domain is much larger than its spatial domain Indeed while relatively few processors can be e ectively utilized in modeling the vehicle via traditional state type al gorithms more than 105 processors may be potentially exploited in a state time dynamic simulation In this paper a modi ed state time methodology is derived in order to ac count for impulsive characteristics This impulsive formulation allows for

Original URL path: http://www.scorec.rpi.edu/reports/view_report.php?id=443 (2015-07-15)

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