Pietro Catalano

Bio: Pietro Catalano is an academic researcher from Italian Aerospace Research Centre. The author has contributed to research in topics: Reynolds-averaged Navier–Stokes equations & Turbulence. The author has an hindex of 9, co-authored 25 publications receiving 307 citations.

U-ZEN: A Computational Tool Solving U-RANS Equations For Industrial Unsteady Applications

Abstract: The purpose of this paper is to assess the capabilities of the newly developed tool U-ZEN, a code solving the Unsteady Reynolds Averaged Navier-Stokes equations. The activity is being performed within a CIRA project focusing on Flow Control; the specific goal for the CFD task is to simulate the unsteady flow phenomena due to particular fluid dynamic conditions (Mach, Reynolds, !) or to time dependent boundary conditions (e.g. flow control devices) around complex 3D configurations. The CIRA steady state flow solver ZEN (Zonal Euler Navier-Stokes) has been extended to treat unsteady problems by introducing a time discretization scheme, namely the Dual Time Stepping (DTS) technique. The validation is performed simulating unsteady flows around bluff obstacles or airfoils/wings at high angles of attack which are available experimental test cases.

Performance Assessment of a Transonic Wing–Body Configuration with Riblets Installed

Abstract: The effectiveness of the riblets, one of the most interesting drag-reduction device, is discussed in this paper. Numerical simulations by the Reynolds-averaged Navier–Stokes equations with the riblets properly taken into account are presented. Riblets are modeled as a singular roughness problem by modifying the classical Wilcox boundary condition for rough walls. The boundary condition is able to predict the flow features in the low roughness range (transitional roughness) where riblets operate. A brief discussion of the simulations performed to validate the model is first presented. Then, a complex wing–body configuration is analyzed, and the overall effect of riblets on the aerodynamic coefficients is evaluated. Calculations of a complete aircraft configuration at transonic conditions show how a proper optimized choice of the riblet height can significantly improve the drag reduction.

U-RANS Modelling of Turbulent Flows Controlled by Synthetic Jets

Abstract: Synthetic Jet technology needs robust and fast simulation tools to grow up as expected by industrial community. The activity presented in this paper is part of a research eort carried out at the Italian Aerospace Research Center (CIRA). The aim is to improve the accuracy of Reynolds-Averaged Navier-Stokes (RANS) techniques in predicting the eect of steady and unsteady flow control devices in medium/high Reynolds number compressible flows. The control of separation is studied by reproducing numerically a low Mach number 2D flow over an hump model which has been tested at NASA Langley Transonic Cryogenic Tunnel. The choice of the above case is related to the presence of an adverse pressure gradient as occurring in a classical airfoil. A boundary condition modelling for synthetic jets is presented along with comparisons between numerical and experimental data.

Boundary Layer Theory

Abstract: The boundary layer equations for plane, incompressible, and steady flow are $$\matrix{ {u{{\partial u} \over {\partial x}} + v{{\partial u} \over {\partial y}} = - {1 \over \varrho }{{\partial p} \over {\partial x}} + v{{{\partial ^2}u} \over {\partial {y^2}}},} \cr {0 = {{\partial p} \over {\partial y}},} \cr {{{\partial u} \over {\partial x}} + {{\partial v} \over {\partial y}} = 0.} \cr }$$

Zonal-detached-eddy simulation of the flow around a high-lift configuration

Abstract: A zonal hybrid Reynolds-averaged Navier-Stokes large-eddy simulation (RANS/LES) approach, called zonal-DES, used to handle a two-dimensional high-lift configuration with deployed slat and flap is presented. This method allows to reduce significantly the cost of an accurate numerical prediction of the unsteady flow around wings compared to a complete LES. Some issues concerning grid generation as well as the use of zonal-detached-eddy simulation for a multi-element airfoil are discussed. The basic planar grid has 250,000 points and the finest spanwise grid has 31 points with Az/c = 0.002. The effort is geared toward detailed comparison of the numerical results with the Europiv2 experimental particle image velocimetry data including both mean and fluctuating properties of the velocity field (Arnott and al)

Origin of transonic buffet on aerofoils

Abstract: Buffeting flow on transonic aerofoils serves as a model problem for the more complex three-dimensional flows responsible for aeroplane buffet. The origins of transonic aerofoil buffet are linked to a global instability, which leads to shock oscillations and dramatic lift fluctuations. The problem is analysed using the Reynolds-averaged Navier–Stokes equations, which for the foreseeable future are a necessary approximation to cover the high Reynolds numbers at which transonic buffet occurs. These equations have been shown to reproduce the key physics of transonic aerofoil flows. Results from global-stability analysis are shown to be in good agreement with experiments and numerical simulations. The stability boundary, as a function of the Mach number and angle of attack, consists of an upper and a lower branch – the lower branch shows features consistent with a supercritical bifurcation. The unstable modes provide insight into the basic character of buffeting flow at near-critical conditions and are consistent with fully nonlinear simulations. The results provide further evidence linking the transonic buffet onset to a global instability.