Model for Enhancing Turbulent Production in Laminar Separation Bubbles

Abstract

Laminar separation bubbles are one of the main critical aspects of flows at low Reynolds numbers in the range of 10 4 -10 5 . The flow separates in the laminar regime, the turbulence developing inside the recirculation region enhances the momentum transport, and the flow can reattach. Models based on the Reynolds-averaged Navier-Stokes equations suffer two of main issues: the determination of the transition onset and the level of the pressure recovery downstream of the reattachment of the flow. A model addressing both issues is presented in this paper. It is based on the γ transition model for the transition detection. The production of the turbulent kinetic energy κ has been properly enhanced thanks to a correlation found between the necessary boosting of κ and the intermittency function behavior within the bubble. The low-Mach-number and Reynolds-number flows around the Selig-Donovan 7003, Eppler 387, and NACA 0015 airfoils are analyzed. The results are compared to experimental data and large-eddy simulations available in the literature. The model can be applied to the analysis of an arbitrary airfoil without need of preliminary calculation of the transition point within the bubble.

Quantification of Reynolds-averaged-Navier-Stokes model form uncertainty in transitional boundary layer and airfoil flows

“…On the other hand, the 3c perturbation produces a larger value of P k than the baseline prediction. This behavior is qualitatively similar to the very recent study of Clara et al 60 , which focused on enhancing the turbulent production in the LSB. On the other hand, P k produced by the 2c perturbation has a comparable magnitude to that for the baseline prediciton, and hence in between the 1c and 3c perturbations.…”

“…From Fig. 11 (b), finding the zeros of the skin friction coefficient is a different technique that can be used to approximate the X S /c, X T /c and X R /c points as well 60 . Based on the reference data, both techniques showed good agreement with each other, and a summary of these transition parameters is presented in Table II.…”

Relaminarization of jet impingement on a flat plate using separation-induced transition correction turbulence modeling preliminarily applied in archeological applications

“…From these limitations, Cerbus [ 27 ] refined the mechanism of laminar and turbulent flow using Prandtl-Tietjens intermittency to explain the fluctuations in internal flow resistance. De Santis et al [ 28 ] enhanced the turbulence in laminar separation bubbles, with the results from the new formulation agreeing well with available experimental data. Carnes and Coder [ 29 ] analyzed the local-correlation laminar-turbulent transition model to develop a new understanding of near-wall behavior.…”

Comparability of Hot-Wire Estimates of Liquid Water Content in SLD Conditions

“…UZEN solves the compressible Navier-Stokes equations based on a multi-block structured approach, and is normally used for simulating steady and unsteady flows around complex aeronautical models. Evidence of its efficacy has been provided through reproduction of flows involving some peculiar phenomena [24,25] and for complex devices [26,27]. The spatial discretization in UZEN consists of a central finite-volume formulation with explicit blended 2nd and 4th order artificial dissipation.…”