Prospects for computing airfoil aerodynamics with Reynolds averaged Navier-Stokes codes

The Reynolds averaged Navier-Stokes equations are solved numerically for a variety of transonic airfoil configurations where viscous phenomena are important. Illustrative examples include flows past sensitive geometries, Reynolds number effects, and buffet phenomena

Transonic separated flow predictions based on a mathematically simple, nonequilibrium turbulence closure model

A mathematically simple, turbulence closure model designed to treat transonic airfoil flows even with massive separation is described. Numerical solutions of the Reynolds-averaged, Navier-Stokes equations obtained with this closure model are shown to agree well with experiments over a broad range of test conditions

Численное моделирование течения вязкого газа через плоскую решетку колеблющихся профилей

The numerical scheme of solving Reynolds-averaged Navier-Stokes equations for simulation of self -exciting oscillations of turbine blade row in transonic viscous gas flow is proposed. The method is based on second order Godunov's scheme. Comparison of numerical results with experimental and theoretical ones is give

Progress and challenges in modeling turbulent aerodynamic flows

Progress in modeling external aerodynamic flows achieved by using computations and experiments designed to guide turbulence modeling is presented. The computational procedures emphasize utilization of the Reynolds-averaged Navier-Stokes equations and various statistical modeling approaches. Developments for including the influence of compressibility are provided; they point up some of the complexities involved in modeling high-speed flows. Examples of complementary studies that provide the status, limitations, and future challenges of modeling for transonic, supersonic, and hypersonic flows are given

Fractional and tempered fractional models for Reynolds-averaged Navier-Stokes equations

Turbulence is a non-local phenomenon and has multiple-scales. Non-locality can be addressed either implicitly or explicitly. Implicitly, by subsequent resolution of all spatio-temporal scales. However, if directly solved for the temporal or spatially averaged fields, a closure problem arises on account of missing information between two points. To solve the closure problem in Reynolds-averaged Navier-Stokes equations (RANS), an eddy-viscosity hypotheses has been a popular modelling choice, where it follows either a linear or non-linear stress-strain relationship. Here, a non-constant diffusivity is introduced. Such a non-constant diffusivity is also characteristic of non-Fickian diffusion equation addressing anomalous diffusion process. An alternative approach, is a fractional derivative based diffusion equations. Thus, in the paper, we formulate a fractional stress-strain relationship using variable-order Caputo fractional derivative. This provides new opportunities for future modelling effort. We pedagogically study of our model construction, starting from one-sided model and followed by two-sided model. Non-locality at a point is the amalgamation of all the effects, thus we find the two-sided model is physically consistent. Further, our construction can also addresses viscous effects, which is a local process. Thus, our fractional model addresses the amalgamation of local and non-local process. We also show its validity at infinite Reynolds number limit. This study is further extended to tempered fractional calculus, where tempering ensures finite jump lengths, this is an important remark for unbounded flows. Two tempered definitions are introduced with a smooth and sharp cutoff, by the exponential term and Heaviside function, respectively and we also define the horizon of non-local interactions. We further study the equivalence between the two definitions.Comment: A part of this paper is also available as arXiv preprint arXiv:2105.03646v1. Tempered F-RANS result first presented at ICTAM 2020+1 held in Italy, 2021 chaired by Prof. A. Quarteroni (postponed by a year due to pandemic). Results submitted to ICTAM 2020 by Jan. 2020 (refer book of abstracts, Pages 1235-1236 : https://iutam.org/wp-content/uploads/2023/06/ABSTRACT_BOOK_ICTAM_2021.pdf

Численное исследование аэроупругого поведения компрессорной ступени в трехмерном потоке вязкого газа

The partial integration method of the solution for the coupled problem of unsteady aerodynamics and elastic blades oscillations has been applied to simulate the aeroelastic behaviour of compressor stage. The three-dimensional unsteady viscous gas flow is written by Reynolds averaged Navier-Stokes equations. The dynamic analysis uses the modal approach. The amplitude-frequency characteristics of the unsteady loads and blades elastic oscillations have been presente

Investigation of the Spalart-Allmares Turbulence Model for Calculating a Centrifugal Separator

A study of SA turbulence models in application to the calculation of swirling currents inside the separator has been carried out. The paper compared two approaches using vorticity and current functions to eliminate pressure and a semi-implicit method for pressure-binding SIMPLE to solve the Reynolds-averaged Navier-Stokes equations. For the numerical solution of both approaches, an implicit method against the flow was used

Effects of airflow on hydrodynamic modulation of short surface waves by long waves

A model is developed for the effects of airflow on hydrodynamic modulation of short surface gravity waves by a dominant long wave. The propagation of the short wave and distribution of its wavenumber and energy density with respect to phase of the long wave are specified by the kinematic conservation equation and the wind-forcing modified wave action equation, which are solved using linear ray theory and modelled by the Reynolds-averaged Navier-Stokes equations

The computation of flow past an oblique wing using the thin-layer Navier-Stokes equations

Essential aspects are presented for computing flow past an oblique wing with the thin-layer Navier-Stokes equations. A new method is developed for generating a grid system around a realistic wing. This method utilizes a series of conformal transformations. The thin-shear-layer approximation and an algebraic eddy-viscosity turbulence model are used to simplify the Reynolds-averaged Navier-Stokes equations. An implicit, factored numerical scheme and the concept of pencil data structure are utilized. For the first time, some flow fields caused by the oblique wing in a supersonic free stream are discussed, emphasizing the separated vortex flows associated with such a wing

Turbulence modeling for sharp-fin-induced shock wave/turbulent boundary-layer interactions

Solutions of the Reynolds averaged Navier-Stokes equations are presented and compared with a family of experimental results for the 3-D interaction of a sharp fin induced shock wave with a turbulent boundary layer. Several algebraic and two equation eddy viscosity turbulence models are employed. The computed results are compared with experimental surface pressure, skin friction, and yaw angle data as well as the overall size of the interaction. Although the major feature of the flow fields are correctly predicted, several discrepancies are noted. Namely, the maximum skin friction values are significantly underpredicted for the strongest interaction cases. These and other deficiencies are discussed