Discontinuous Galerkin Turbulent Flow Simulations of NASA Turbulence Model Validation Cases and High Lift Prediction Workshop Test Case DLR-F11

2016 ◽  
Author(s):  
Michael J. Brazell ◽  
Behzad R. Ahrabi ◽  
Dimitri J. Mavriplis
Keyword(s):  
Turbulent Flow ◽  
Model Validation ◽  
Discontinuous Galerkin ◽  
Turbulence Model ◽  
Test Case ◽  
High Lift ◽  
Flow Simulations

scholarly journals Supersonic turbulent flow simulation using a scalable parallel modal discontinuous Galerkin numerical method

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Tomas Houba ◽  
Arnob Dasgupta ◽  
Shivasubramanian Gopalakrishnan ◽  
Ryan Gosse ◽  
Subrata Roy
Keyword(s):  
Reynolds Number ◽  
Turbulent Flow ◽  
Discontinuous Galerkin ◽  
Stokes Equations ◽  
Parallel Computer ◽  
Navier Stokes ◽  
Finite Difference Schemes ◽  
Performance Study ◽  
Navier Stokes Equations ◽  
Flow Simulations

Abstract The scalability and efficiency of numerical methods on parallel computer architectures is of prime importance as we march towards exascale computing. Classical methods like finite difference schemes and finite volume methods have inherent roadblocks in their mathematical construction to achieve good scalability. These methods are popularly used to solve the Navier-Stokes equations for fluid flow simulations. The discontinuous Galerkin family of methods for solving continuum partial differential equations has shown promise in realizing parallel efficiency and scalability when approaching petascale computations. In this paper an explicit modal discontinuous Galerkin (DG) method utilizing Implicit Large Eddy Simulation (ILES) is proposed for unsteady turbulent flow simulations involving the three-dimensional Navier-Stokes equations. A study of the method was performed for the Taylor-Green vortex case at a Reynolds number ranging from 100 to 1600. The polynomial order P = 2 (third order accurate) was found to closely match the Direct Navier-Stokes (DNS) results for all Reynolds numbers tested outside of Re = 1600, which had a normalized RMS error of 3.43 × 10−4 in the dissipation rate for a 603 element mesh. The scalability and performance study of the method was then conducted for a Reynolds number of 1600 for polynomials orders from P = 2 to P = 6. The highest order polynomial that was tested (P = 6) was found to have the most efficient scalability using both the MPI and OpenMP implementations.

High-order discontinuous Galerkin spectral element methods for transitional and turbulent flow simulations

2014 ◽  
Vol 76 (8) ◽  
pp. 522-548 ◽  
Author(s):  
Andrea D. Beck ◽  
Thomas Bolemann ◽  
David Flad ◽  
Hannes Frank ◽  
Gregor J. Gassner ◽  
...  
Keyword(s):  
Turbulent Flow ◽  
Discontinuous Galerkin ◽  
Spectral Element ◽  
High Order ◽  
Spectral Element Methods ◽  
Flow Simulations

CFD Analysis of a Captive Bullet Entry in Calm Water With and Without Turbulence

2019 ◽  
Author(s):  
René Bettencourt Rauffus ◽  
António Maximiano ◽  
Luís Eça ◽  
Guilherme Vaz
Keyword(s):  
Experimental Data ◽  
Turbulent Flow ◽  
Turbulence Model ◽  
Computational Cost ◽  
Longitudinal Force ◽  
The Body ◽  
Test Case ◽  
Vertical Force ◽  
Pitch Moment ◽  
The Difference

Abstract Simulations are carried out for a simplified lifeboat drop test case, which consists of a captive axisymmetric generic lifeboat shape (bullet), that penetrates the water surface at a constant velocity and angle of attack. The quantities of interest are the body fixed longitudinal force FX, vertical force FZ, and pitch moment MYY.This case was previously used in a verification and validation exercise [1]. Here, a step forward in complexity is taken, as the previous numerical model is now supplemented with the eddy-viscosity based turbulence model k–ω SST. Both approaches are then used to simulate two different cases: Case 1 with minimal wake effects; and Case 3 with flow separation and significant wake. The results are compared with the experimental data. The numerical uncertainty is estimated for both models. It is seen that for Case 1 the difference between both models is mostly within the comparison uncertainty, except for the longitudinal force FX, where the turbulent flow predicts a larger force, improving the comparison with the experiments. The loads predicted with turbulent flow stayed mostly within 6 % of the laminar flow. For Case 3 small differences between both models are found during/after the wake collapse stage. However, this difference is often within the comparison uncertainty. A reasonable agreement is found with the experimental data, except for FZ after the bow wake collapse. The turbulent flow improves slightly on the laminar approach regarding the agreement with the experiments, however it can be argued if this difference justifies the increased computational cost of the turbulence model.

scholarly journals Turbulence model performance for ventilation components pressure losses

2021 ◽  
Author(s):  
Karsten Tawackolian ◽  
Martin Kriegel
Keyword(s):  
Reynolds Number ◽  
Turbulence Model ◽  
Pressure Loss ◽  
Low Reynolds Number ◽  
Turbulence Models ◽  
Reynolds Numbers ◽  
Test Case ◽  
Pressure Losses ◽  
Loss Coefficients ◽  
Near Wall

AbstractThis study looks to find a suitable turbulence model for calculating pressure losses of ventilation components. In building ventilation, the most relevant Reynolds number range is between 3×104 and 6×105, depending on the duct dimensions and airflow rates. Pressure loss coefficients can increase considerably for some components at Reynolds numbers below 2×105. An initial survey of popular turbulence models was conducted for a selected test case of a bend with such a strong Reynolds number dependence. Most of the turbulence models failed in reproducing this dependence and predicted curve progressions that were too flat and only applicable for higher Reynolds numbers. Viscous effects near walls played an important role in the present simulations. In turbulence modelling, near-wall damping functions are used to account for this influence. A model that implements near-wall modelling is the lag elliptic blending k-ε model. This model gave reasonable predictions for pressure loss coefficients at lower Reynolds numbers. Another example is the low Reynolds number k-ε turbulence model of Wilcox (LRN). The modification uses damping functions and was initially developed for simulating profiles such as aircraft wings. It has not been widely used for internal flows such as air duct flows. Based on selected reference cases, the three closure coefficients of the LRN model were adapted in this work to simulate ventilation components. Improved predictions were obtained with new coefficients (LRNM model). This underlined that low Reynolds number effects are relevant in ventilation ductworks and give first insights for suitable turbulence models for this application. Both the lag elliptic blending model and the modified LRNM model predicted the pressure losses relatively well for the test case where the other tested models failed.

scholarly journals An improved Immersed Boundary Method for turbulent flow simulations on Cartesian grids

2021 ◽  
pp. 110240
Author(s):  
Benjamin Constant ◽  
Stéphanie Péron ◽  
Héloïse Beaugendre ◽  
Christophe Benoit
Keyword(s):  
Turbulent Flow ◽  
Immersed Boundary Method ◽  
Immersed Boundary ◽  
Cartesian Grids ◽  
Flow Simulations ◽  
Boundary Method

Simulation of the Transitional Flow in a Low Pressure Gas Turbine Cascade With a High-Order Discontinuous Galerkin Method

2013 ◽  
Vol 135 (7) ◽  
Author(s):  
A. Ghidoni ◽  
A. Colombo ◽  
S. Rebay ◽  
F. Bassi
Keyword(s):  
Discontinuous Galerkin ◽  
Turbulence Model ◽  
Stokes Equations ◽  
Time Integration ◽  
High Order ◽  
Transitional Flow ◽  
Navier Stokes ◽  
Implicit Time ◽  
Turbine Cascade ◽  
High Reynolds

In the last decade, discontinuous Galerkin (DG) methods have been the subject of extensive research efforts because of their excellent performance in the high-order accurate discretization of advection-diffusion problems on general unstructured grids, and are nowadays finding use in several different applications. In this paper, the potential offered by a high-order accurate DG space discretization method with implicit time integration for the solution of the Reynolds-averaged Navier–Stokes equations coupled with the k-ω turbulence model is investigated in the numerical simulation of the turbulent flow through the well-known T106A turbine cascade. The numerical results demonstrate that, by exploiting high order accurate DG schemes, it is possible to compute accurate simulations of this flow on very coarse grids, with both the high-Reynolds and low-Reynolds number versions of the k-ω turbulence model.

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