55,896 research outputs found
Software technologies for future embedded and ubiquitous systems
No full text6th IFIP WG 10.2 International Workshop, SEUS 2008, Anacarpi, Capri Island, Italy, October 1-3, 2008 Proceeding
Malgrange's vanishing theorem for weakly pseudoconcave CR manifolds
No full textThe authors prove the following CR version of Malgrange's theorem: Assume M is a smooth, non-compact, weakly pseudoconcave CR manifold of type (n,k) of finite kind. Then the highest ∂−M cohomology Hp,n∂−M(M) vanishes for 0≤p≤n+k. This generalises a similar result for real analytic CR manifolds by the third author [in Hyperbolic problems and regularity questions, 137--150, Birkhäuser, Basel, 2007; MR2298789 (2008d:32034)].
Furthermore, they prove the following approximation theorem: If M is as above and U⊂⊂V⊂⊂M are two open sets such that V\sbs UV∖U has no compact connected component then for 0≤p≤n+k the restriction map Zp,n−1(V−)→Zp,n−1(U) has dense image, with respect to the \scr C^\inftyC∞ topology on U. The authors prove the following CR version of Malgrange's theorem: Assume M is a smooth, non-compact, weakly pseudoconcave CR manifold of type (n,k) of finite kind. Then the highest ∂−M cohomology Hp,n∂−M(M) vanishes for 0≤p≤n+k. This generalises a similar result for real analytic CR manifolds by the third author [in Hyperbolic problems and regularity questions, 137--150, Birkhäuser, Basel, 2007; MR2298789 (2008d:32034)].
Furthermore, they prove the following approximation theorem: If M is as above and U⊂⊂V⊂⊂M are two open sets such that V\sbs UV∖U has no compact connected component then for 0≤p≤n+k the restriction map Zp,n−1(V−)→Zp,n−1(U) has dense image, with respect to the \scr C^\inftyC∞ topology on U. The authors prove the following CR version of Malgrange's theorem: Assume M is a smooth, non-compact, weakly pseudoconcave CR manifold of type (n,k) of finite kind. Then the highest ∂−M cohomology Hp,n∂−M(M) vanishes for 0≤p≤n+k. This generalises a similar result for real analytic CR manifolds by the third author [in Hyperbolic problems and regularity questions, 137--150, Birkhäuser, Basel, 2007; MR2298789 (2008d:32034)].
Furthermore, they prove the following approximation theorem: If M is as above and U⊂⊂V⊂⊂M are two open sets such that V\sbs UV∖U has no compact connected component then for 0≤p≤n+k the restriction map Zp,n−1(V−)→Zp,n−1(U) has dense image, with respect to the \scr C^\inftyC∞ topology on U
Architecture of Computing Systems - ARCS 2011
No full textArchitecture of Computing Systems - ARCS 2011,
24th International Conference, Como, Italy, February 24-25, 2011. Proceeding
Journal of Software - Special Issue: Selected Papers of the 6th IFIP Workshop on Software Technologies for Future Embedded and Ubiquitous Systems (SEUS 2008)
No full textA Dynamic Subfilter-scale Stress Model for Large Eddy Simulations Based on Physical Flow Scales
No full textWe propose a new definition of the length scale in an eddy-viscosity model for large-eddy simulations (LES). This formulation extends and generalizes a previous proposal [Piomelli, Rouhi and Geurts, Proc. ETMM10, 2014], in which the LES length scale was expressed in terms of the integral length-scale of turbulence determined by the flow characteristics and explicitly decoupled from the simulation grid; this approach was named Integral Length-Scale Approximation (ILSA). As in the original ILSA, the model coefficient was determined by the user, and required to maintain a desired contribution of the unresolved, subfilter scales (SFS) to the global transport. We propose a local formulation (local ILSA) in which the model coefficient is local in space, allowing a precise control over SFS activity as a function of location. This new formulation preserves the properties of the global model; application to channel flow and backward-facing step verifies its features and accuracy
Large-eddy simulation of a separated flow with a sub-filter scale model based on the integral length-scale
No full textA new sub-filter scale model for large-eddy simulations, which uses a length-scale proportional to the integral scale of the turbulence instead of the grid resolution to parametrize the modelled stresses, will be assessed in the prediction of the flow of a boundary-layer over a rough surface, which includes separation and reattachment
Near Wall PIV-Measurements on the Windward Slope of a Hill
No full textThe turbulent flow over periodic hills was measured near to the wall, using planar Particle-Image-Velocimetry (PIV) at high spatial resolution. Our focus is on the near wall turbulence structure on the windward slope of the hill. For large-eddy simulation (LES) we suspect that, if this was not predicted accurately, it affects the prediction of the velocity profiles over the hill crest which in turn will affect the recirculation length downstream of the hill. Regarding the time averaged velocities, we were able to resolve the linear viscous region of the boundary layer. The velocity distribution and also the Reynolds stress does not comply with the law of the wall as it is valid for a turbulent boundary layer at equilibrium
Energy dissipation and flux laws for unsteady turbulence
No full textDirect Numerical Simulations of spatially periodic unsteady turbulence show that the high Reynolds number scalings of the instantaneous energy dissipation rate and interscale energy flux at intermediate wavenumbers are qualitatively different from the well-known cornerstone scalings of equilibrium turbulence where and are time-dependent rms velocity and integral length-scales. Instead, they both scale as where and are length and velocity scales characterizing initial/overall unsteady turbulence conditions
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