PDF Simulations of a Bluff-Body Stabilized Flow

Abstract

Three different PDF algorithms have been applied to investigate a constant-density bluff-body stabilized flow using the same turbulence models and the same boundary conditions. The objectives of this paper are to compare the three algorithms in terms of numerical accuracy and efficiency and to demonstrate the ability of PDF methods to calculate this type of flow accurately. While one of the three algorithms is a standalone particle-mesh method, the other two are consistent hybrid algorithms, i.e., both are particle methods coupled with finite-volume schemes. The motivation for hybrid algorithms is to reduce the statistical and bias errors. Since the coupling between the finite-volume scheme and the particle method is a major numerical issue, different approaches have been investigated. It is shown that the results obtained from the three numerical algorithms are in good agreement with each other and with the experimental data.

Numerical Investigation of a Bluff-Body Stabilised Nonpremixed Flame with Differential Reynolds-Stress Models

“…Here, the boundary conditions are carefully determined as follows. The inflow and the boundary conditions are specified in the same way as for the cold bluff-body case studied by Jenny et al [9]. At the jet and coflow regions of the boundary, the experimental data are used for the axial velocity of the coflow, and also the profiles of normal Reynolds stresses of the centre jet and coflow are obtained and calculated from the experimental data.…”

“…At the jet and coflow regions of the boundary, the experimental data are used for the axial velocity of the coflow, and also the profiles of normal Reynolds stresses of the centre jet and coflow are obtained and calculated from the experimental data. The axial velocity in the central jet region, the shear Reynolds stress, and the dissipation rate are all calculated according to the formula provided in [9]. The results are found to be rather insensitive to the applied boundary condition at the bluff body face, either no-slip boundary condition, with standard wall functions or free slip boundary condition.…”

“…The bluff-body stabilised flame has received special attention and been widely studied recently [3,4,8,9,12,13,19,20,28,29]. In addition to its practical interest, the bluff-body flame is a very challenging test for turbulence models as well as chemistry models.…”

“…But it is noteworthy that all models employed in [19] underestimate the persistence of the jet, which means that the minimum value of the velocity on the symmetry axis is underpredicted especially further downstream. The same flame has also been modelled with a conditional moment closure (CMC) model by Kim et al [12,13] and with a coupled radiation/flamelet combustion model by Hossain et al [8], and also with Monte Carlo PDF models by Jenny et al [9] and Muradoglu et al [20] more recently. A similar bluff-body stabilised flame with different geometrical configuration and fuel has also been studied numerically by Wouters et al [28][29][30] using k-model and Reynolds-stress models as well as hybrid finite volume/Monte Carlo PDF model.…”

A Hybrid Finite-Volume/Transported PDF Model for Simulations of Turbulent Flames on Vector Machines

“…One possibility is to couple the particle method with an ordinary finite-volume or finite-difference solver to obtain the mean pressure field from the Navier-Stokes equations. These so called hybrid PDF/CFD methods are widely used by different authors for many types of flames [15,16,17,18,19,20]. In the presented paper a hybrid scheme is presented and used as well.…”