Multiscale Computation of Turbulence
Participants: S.J. Hulshoff, P.W. Fick, I. Akkerman
Collaboration: T. Hughes, University of Texas at Austin; Y. Bazilevs UCSD.
Funding Sources: STW, STW-DFG
Description:
Variational-multiscale methods are particularly well suited for large-eddy simulations of turbulent flows, as they unify concepts of discretisation and modelling errors, avoid ambiguities in interpretation near boundaries, and provide flexibility in the application of unresolved-scale models. Our work is directed towards the development of variational-multiscale methods which provide high fidelity representations of wall-bounded turbulent flows while using relatively few degrees of freedom.
Firstly, we are developing general finite-element method methods which can be used for efficient local hp refinement in complex domains, based on multiscale discontinuous Galerkin concepts. Secondly, we are pursuing the development of goal-based error estimation techniques to facilitate the construction of fully-adaptive schemes. Thirdly, we are investigating the application of general variational-Germano identities to the calibration of unresolved-scale models. Lastly, we are investigating the design of weak boundary conditions and residual-based unresolved-scale models for wall-bounded flows. Ultimately these techniques will be combined with the goal of providing highly efficient estimates for the turbulent flow quantities of most relevance to aerospace design.
Additional Information:
Adaptive computation of turbulent flows with separation
Gallery of Results:
Near-wall streaks computed using three-scale VMS on a 16x16x16/p2 mesh.
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Streamwise fluctuation profiles for standard (SvD) and Variational Multiscale (VM) Smagorinsky models with 8x8x8/p2 and 16x16sx16/p2 meshes (Spanwise streak wavelength captured in small scales of 16x16sx16/p2 mesh)
Comparison of exact, Franca and four Variational-Germano optimized upwind functions as a function of mesh Peclet number (the upwind function determines the unresolved-scale representation for convection-diffusion flows).
Mean profiles obtained via wall modelling on extremely coarse meshes.
Related Publications:
Akkerman I., Bazilevs, Y., Calo, V.M., Hughes, T.J. R. and Hulshoff, S., “The role of continuity in residual-based variational multiscale modeling of turbulence”, Computational Mechanics, 41 (2008) 371-378.
Akkerman I., Hulshoff, S.J, de Borst, R, "Multiscale overlap coupling for hybrid computations", CMAME 196 (2007) 4294-4303.
Munts, E.A., Hulshoff, S.J, de Borst, R, "A model based multiscale method for large eddy simulations", Journal of Computational Physics 224 (2007) 389-402
Hulshoff, S.J., Implicit subgrid-scale models in space-time variational-multiscale discretisations, Int. J. Numer. Meth. Fluids (2005); 47(10-11):1093-1099
