Abstract

The HiFi-TURB-DLR rounded step test case is designed to investigate the effect of an adverse pressure gradient on a turbulent boundary layer. The problem considers the flow over a 2D planar rounded step, see Fig. 1, and is inspired by the axisymmetric rounded step proposed by Disotell and Rumsey, see Disotell et al., Disotell et al. (2017) and Alaya et al. (2021).

This test case concerns an under-resolved Direct Numerical Simulation (uDNS) using the high-order discontinuous Galerkin (DG) code MIGALE, see Bassi et al. (2016). The code couples the DG space discretization with a high-order implicit time integration, which relies on Rosenbrock schemes.

The primary objective of this contribution is to provide a rich database of flow and turbulence statistics as a reference target for verification and validation of RANS models (see UFR 3-36 Test Case).

The provided statistical quantities in the database are:

• mean pressure and velocity components;
• Reynolds stress components;
• Taylor microscale;
• Kolmogorov length and time scales;

As the solver discretizes the compressible Navier-Stokes equations, density and temperature fields, as well their gradients, have been collected during the computational campaign. However, since the flow regime is incompressible (${\displaystyle {Ma=0.13455}}$), these fields are a side product of this contribution and thus are not reported.

 Figure 1: HiFi-TURB-DLR rounded step, Re=78,490. Dimensionless instantaneous streamwise velocity at midspan using MIGALE with DG P3 (~300 million DoF/eqn).

University of Bergamo acknowledges PRACE for awarding the access to JUWELS hosted by GCS at FZJ, Germany.

References

1. Disotell, K. J. and Rumsey, C. L.: Modern CFD validation of turbulent flow separation on axisymmetric afterbodies.
2. Disotell, K. J. and Rumsey, C. L. (2017): Development of an axisymmetric afterbody test case for turbulent flow separation validation. NASA/TM-2017219680, Langley Research Center, Hampton, Virginia
3. Alaya, E., Grabe, C. and Knopp, T. (2021): Design of a parametrized numerical experiment for a 2D turbulent boundary layer flow with varying adverse pressure gradient and separation behaviour. DLR-IB-AS-GO-2020-109, DLR-Interner Bericht, DLR Institute of Aerodynamics and Flow Technology
4. Bassi, F., Botti, L., Colombo, A. C, Ghidoni, A. and Massa, F. (2016): 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, Vol. 55(2), pp. 367-379

Contributed by: Francesco Bassi, Alessandro Colombo, Francesco Carlo Massa — Università degli studi di Bergamo (UniBG)