Turbulent Flow Past Two-Body Configurations

Flows Around Bodies

Underlying Flow Regime 2-12

Description

Introduction

The UFR in question may be considered of relevance to the Application Challenge AC 1–08 (L1T2 3 element airfoil) and, to some extent, to AC 4–01 (wind environment around an airport terminal building). It is characterized by several common features which include separation of turbulent boundary layer from the upstream body, free shear layer roll-up, and interaction of unsteady wake forming in the gap between bodies with the downstream one. Capturing these features is known to be a serious physical (in terms of a proper turbulence representation) and computational (in terms of numerics and computer resources) challenge, which motivates systematic thorough studies aimed at an objective evaluation of capability of existing modelling approaches/numerical techniques to predict them with acceptable accuracy.

A purpose of this document is to provide a summary of findings of such a study undertaken in the framework of the EU Research Collaborative Project "Advanced Turbulence simulation for Aerodynamic Application Challenges" (ATAAC) [1] for the Tandem Cylinders (TC) configuration as a representative example of the considered UFR. The document is organized as follows.

   First, a brief overview of the studies of the TC flow is given  with  a
   focus on those carried out in the course of the  ATAAC  project,  whose
   outcome presents a core of the subsequent analysis. Then, an outline of
   the NASA experiments [2]-[4] is given, after which  a  summary  of  CFD
   methods  used,  results  of  the  simulations  performed,   and   their
   comparison with the experimental data are presented.  Finally,  in  the
   BPA section, some practical advice on computing the considered  UFR  is
   given based on findings of the  performed  analysis.  Note  that  these
   findings should be considered not as stand alone ones but together with
   those  of  the  Workshop  on  Benchmark  problems  for  Airframe  Noise
   Computations (BANC-I) [5] and forthcoming BANC-II Workshops.

Review of UFR studies and choice of test case

Provide a brief review of past studies of this UFR which have included test case comparisons of experimental measurements with CFD results. Identify your chosen study (or studies) on which the document will focus. State the test-case underlying the study and briefly explain how well this represents the UFR? Give reasons for this choice (e.g a well constructed test case, a recognised international comparison exercise, accurate measurements, good quality control, a rich variety of turbulence or physical models assessed etc.) . If possible, the study should be taken from established data bases. Indicate whether of not the experiments have been designed for the purpose of CFD validation (desirable but not mandatory)?

Contributed by: A. Garbaruk, M. Shur and M. Strelets — New Technologies and Services LLC (NTS) and St.-Petersburg State Polytechnic University