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This study explores the constraints and predictions of pressure-strain correlation tensor models in turbulence analysis. The research delves into spectral representation, differential Reynolds stress models, and the connection between spectral approach and closure models. Results offer insights into turbulence behavior and reveal areas for model improvement.
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Constraints for the Pressure-Strain Correlation tensor derived from Spectral Representation S.R.Bogdanov T.J.Jongen EFMC-6, Stockholm, 2006
Outline • DRSM, PSC models • The derivation of the restrictions on the “rapid” part of PSC. • Direct checking of the models for • Predicting the available areas of the parameters of stationary states • Others: (Implicit) checking of the models for non-linear part of PSC, non-uniform turbulence … EFMC-6, Stockholm, 2006
Differential Reynolds stress models, DRSM Spectra of ideas, connected with the study of fully developed turbulence and calculations of the flows with the anisotropy is extremly wide: from the theory of fractals and renormalization group methods to direct numeric simulations and semiempirical modelling. At the same time nowadays the so-called first (with the turbulent viscosity as the key concept) and second-order closure (or full differential Reynolds stress models, DRSM). models are the most popular in practice. EFMC-6, Stockholm, 2006
A lot of models were proposed for PSC. One of the most popular and well-known (quasi-linear) semi-empirical approximations for PSC looks like: EFMC-6, Stockholm, 2006
Realizability criteria EFMC-6, Stockholm, 2006
The derivation of the restrictions on the “rapid” part of PSC. EFMC-6, Stockholm, 2006
Illustration of the basic idea EFMC-6, Stockholm, 2006
Direct checking of the models for PSC EFMC-6, Stockholm, 2006
It's convenient to present the available areas for the set ofparameters B with graphic on B_3 - {B_2}/R plane. Available is the insidearea of the triangle ABC. 2-D turbulence corresponds to the sides ofthe triangle; points A,B,C correspond to 1-dimensional turbulence(with pulsations along axes 3,1,2).BE, CF, AD - present axisymmetric turbulence;At last, point O presents isotropic turbulence. The set of hyperbola (B_1 - isolines) isalso presented on the picture.When B_1 is fixed, the area of available values of theparameters B_2 и B_3/R is restricted with correspondent hyperbolaand BC- line. Y – axis: B3= -b33/2 X-axis: B2/R = (b11 – b22)/2 EFMC-6, Stockholm, 2006
The available domain on invariant map EFMC-6, Stockholm, 2006
B3 - isolines EFMC-6, Stockholm, 2006
B2 - isolines, for B1=0 EFMC-6, Stockholm, 2006
«Forbidden» areas on invariant map (SSG model, R=0, B1=0 and -0.1 correspondently) EFMC-6, Stockholm, 2006
Stationary state analysis, SSG EFMC-6, Stockholm, 2006
Conclusion • Possibilities of direct checking (and improving, hopefully: at least, through the proper choice of the set of the model constants) of PSC models • Direct analysis of the parameters of stationary states. • The link between spectral approach and one-point closures. • Most probably turbulence is more non-local than it’s usually assumed within second-order closures. EFMC-6, Stockholm, 2006
Thank you EFMC-6, Stockholm, 2006