Full-scale experimental and computational fluid dynamics (CFD) methods were used to investigate buoyancy-driven single-sided natural ventilation with large openings. Detailed airflow characteristics inside and outside of the room and the ventilation rate were measured. The experimental data were used to validate two CFD models: Reynolds averaged Navier-Stokes equation (RANS) modeling and large ...

Accurate and reliable CFD simulation of temperature stratification in indoor environment is needed for the design and evaluation of displacement ventilation in buildings. This paper presents a detailed and systematic evaluation of the capability of 3D steady RANS CFD simulations to predict the temperature stratification in a room. The evaluation is based on sensitivity analysis and validation w...

Validation simulations are presented for turbulent flow in a staggered tube bank, geometry similar to the lower plenum of a gas-cooled high temperature reactor. Steady 2D RANS results are compared to unsteady 2D RANS results and experiment. The unsteady calculations account for the fact that nonturbulent fluctuations (due to vortex-shedding) are present in the flow. The unsteady computations ar...

The majority of industrial computational fluid dynamics simulations are steady. Such simulations therefore require numerical methods which can rapidly converge a boundary value problem, typically either the Euler or Reynolds-averaged Navier–Stokes (RANS) equations. In this chapter we outline two major approaches: time-marching methods built on top of Runge–Kutta time-stepping schemes and Newton...

High-order methods have demonstrated their potential in large eddy simulations (LES) of turbulent flows with relatively low Reynolds numbers. The cost becomes a serious limiting factor for high Reynolds number problems. A promising approach to reduce the cost of these simulations is the hybrid Reynolds-Averaged Navier-Stokes (RANS)/LES approach. In this paper, a new hybrid RANS-Implicit LES (IL...

In this work a robust discontinuous Galerkin (DG) solver for turbulent high-lift aerodynamic flows using the turbulence model of Spalart and Allmaras (SA) is developed. The application of DG discretizations to turbulent RANS flows is one of the most pressing issues facing high-order methods on unstructured grids. The issue is the result of non-smooth behavior of the turbulence model equation, w...

This paper presents a time-accurate procedure for computing unsteady aerodynamic forces on wings with a full-span oscillating control surface by using sheared grids. In this procedure, the flow is computed by solving the unsteady Reynolds-Averaged Navier-Stokes (RANS) equations in conjunction with the one-equation Spalart-Allmaras turbulence model. A module to model control surface oscillations...

We study a new hybrid RANS/Variational Multiscale LES (VMS-LES) model for bluff body flows. The simulations have been carried out using a parallelized solver, based on a mixed element/volume formulation on unstructured grids. First, the behavior of a VMS-LES model with different subgrid scale models is investigated for the flow past a circular cylinder at Reynolds number Re =3900. Second, a new...