DNS 1-5
Lib:Flow over a rounded step
Abstract
The present test case was designed to investigate the effect of an adverse pressure gradient on a turbulent boundary layer. The problem considers the flow over a 2D rounded step, see, Fig. 1, defined at UFR_X-YZ_Test_Case and inspired by the axisymmetric one proposed by Disotell and Rumsey [1,2,3].
At the inlet a Blasius profile with Re_x=650000 for the velocity, a uniform profile for static pressure and uniform profile for total temperature are imposed. Transition to turbulence is promoted downstream by means of a local forcing term. At the outlet, a standard Dirichlet condition for the pressure is prescribed. At the upper boundary a freestream condition is set. The Reynolds number is Re= 78490 and is based on freestream properties and step height. The flow is considered compressible with Mach number based on freestream properties equal to Ma=0.13455.
The dataset concerns the scale-resolving simulation of the turbulent flow over a rounded step using the high-order discontinuous Galerkin (DG) code MIGALE [4]. The code couples the high-order DG spatial discretization with high-order implicit time integration using Rosenbrock-type schemes, here of the fifth order [5,6]. The primary objective of this contribution is to provide a rich database of flow and turbulence statistics for verification and validation on subsequent computational campaigns.
The provided statistical quantities in the database are:
- mean pressure, temperature, density and velocity components;
- Favre averaged velocity and temperature;
- mean shear stress and heat flux;
- Reynolds stress components;
- pressure, temperature and density autocorrelations;
- Favre velocity triple correlation;
- pressure-velocity correlation;
- Reynolds stress equations budget terms;
- Taylor microscale;
- Kolmogorov length and time scales;
WIP …
- shear stress-velocity correlation;
- Difference between the Renynolds and the Favre average.
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| Figure 1: Rounded step case, Re=78490. Dimensionless instantaneous streamwise velocity at midspan using MIGALE with DG P3 (~300 million DoF/eqn). |
References
[1] K. J. Disotell and C. L. Rumsey, "Modern CFD validation of turbulent flow separation on axisymmetric afterbodies"
[2] K. J. Disotell and C. L. Rumsey, "Development of an axisymmetric afterbody test case for turbulent flow separation validation", NASA/TM-2017219680, Langley Research Center, Hampton, Virginia, 2017
[3] E. Alaya, C. Grabe, T. Knopp, "Design of a parametrized numerical experiment for a 2D turbulent boundary layer flow with varying adverse pressure gradient and separation behaviour", DLR-Interner Bericht. DLR-IB-AS-GO-2020-109. DLR Institute of Aerodynamics and Flow Technology, 2021
[4] Bassi, F., Botti, L., Colombo, A. C, Ghidoni, A., Massa, F., "On the development of an implicit high-order Discontinuous Galerkin method for DNS and implicit LES of turbulent flows”, European Journal of Mechanics, B/Fluids, 2016
[5] Di Marzo, G., “RODAS5(4) - Méthodes de Rosenbrock d'ordre 5(4) adaptées aux problèmes différentiels-algébriques", MSc Mathematics Thesis, Faculty of Science, University of Geneva, 1993
[6] Bassi, F., Botti, L., Colombo, A., Ghidoni, A., Massa, F., “Linearly implicit Rosenbrock-type Runge-Kutta schemes applied to the Discontinuous Galerkin solution of compressible and incompressible unsteady flows”, Computers and Fluids, 2015
Contributed by: Francesco Bassi, Alessandro Colombo, Francesco Carlo Massa — Università degli studi di Bergamo (UniBG)
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