A web-services accessible turbulence database and application to a-priori testing of a matrix exponential subgrid model

Abstract

We review a new public database of isotropic turbulence and methods of accessing it. In particular, aWeb-Services Method is used that enables analysis programs running on user’s local computer to access the database with subroutine-like calls to the data over the Internet. The data are from DNS of isotropic turbulence at Rλ ∼ 430 and contain 1 turn-over time evolution of a 10243 simulation, with 1024 stored time-steps. User-defined functions are implemented as stored procedures on the database servers, and include functions such as differentiation, interpolation, box-filtering as well as calculation of subgrid-scale stresses. These functions are used to evaluate a-priori a new subgrid scale model based on matrix exponentials proposed in Li et al. (J. Turbul. 9(31):1–29, 2008). It is found that correlation coefficients for this model are significantly higher than for eddy-viscosity closures. However, expansions of the matrix exponential can be used to relate the model to prior nonlinear models, which suggests that the increased correlation may not be dynamically significant. The need for additional public databases for wall-bounded flows, such as channel flow, is highlighted.