A new wall model for LES is proposed. Unlike conventional zonal approaches, given Reynolds stresses are not imposed as the solution, but used as constraints on the SGS stress so that the given Reynolds stress closely matches the computed one only in the mean sense. Also, since LES in general outperforms RANS even at coarse resolution except very near the wall, RANS constraints are limited to th...

The purpose of this work is to compare di erent low-Reynolds-number turbulence models and their suitability for the highly three dimensional return channel with a deswirl cascade. A comparison is made between Chien's k model, Chien's model with a rotational correction, Gatski et al. ARSM and the full Reynolds stress model by Speziale et al.. Experiments are provided by Concepts ETI. MAIN RESULT...

A formulation to include the e ects of wall proximity in a second moment closure model that utilizes a tensor representation for the redistribution terms in the Reynolds stress equations is presented The wall proximity e ects are modeled through an elliptic relaxation process of the tensor expansion coef cients that properly accounts for both correlation length and time scales as the wall is ap...

We re-examine the Boussinesq hypothesis of an effective turbulent viscosity within the context of simple closure considerations for models of strong magnetohydrodynamic turbulence. Reynolds-stress and turbulent Maxwell-stress closure models will necessarily introduce a suite of transport coefficients, all of which are to some degree model-dependent. One of the most important coefficients is the...

Four classes of turbulence models (algebraic, k − , k − ω and a differential Reynolds-stress model) are applied to boundary layers under adverse pressure gradient with a constant equilibrium parameter β = δ * τ w dp dx. Numerical solutions up to Re θ = 10 8 give the classical scalings in the inner and outer layer for all models. Comparison is made with experiments of Clauser at β ≈ 2 and 8 and ...

Laser Doppler Velocimetry (LDV) has been employed to determine pseudo-turbulence characteristics of the flow field around bubble train forming in non-Newtonian caboxymethylcellulose (CMC) aqueous solution at low gas flow rate condition. The Reynolds stress and turbulent intensity of the liquid were investigated by means of Reynolds time-averaged method. The experimental results show that ax...

In this paper, the turbulent air droplet flow inside a single passage of a curved type vane separator has been studied numerically. The simulation is based on the Eulerian - Lagrangian method. For turbulent air flow calculations, a computer code was developed to solve the Reynolds Averaged Navier Stokes (RANS) equations together with the equations of Reynolds Stress Transport Model (RSTM) o...

For developing a reliable data-driven Reynold stress tensor (RST) model, successful reconstruction of the mean velocity field based on high-fidelity information (i.e., direct numerical simulations or large-eddy simulations) is crucial and challenging, considering ill-conditioning problem Reynolds-averaged Navier–Stokes (RANS) equations. It shown that frozen treatment Reynolds force vector (RFV)...

Microscopic structure in bubbly flows is a topic of interest in the study of fluid flows. In the present paper, the Ultrasonic Doppler Method was applied to the measurement of bubbly flows from which Reynolds stress profiles were obtained. Experiments were carried out for an air-water dispersed bubbly flow in a 20mm x 100 mm vertical rectangular channel having a void fraction smaller than 3%. T...

in this study, the effect of suction and the parameters such as suction amplitude, suction coefficient and suction jet length on naca0012 was evaluated. the turbulence employed model was the rsm model. suction jet is located in 10% of the chord length. the range of suction jet entrance velocity was selected from 0.1 to 0.5 of freestream velocity. the maximum increase in lift to drag ratio was s...