A Wall-Distance-Free k-ε Model With Enhanced Near-Wall Treatment

Abstract

This paper evaluates a wall-distance-free low-Re k-ε turbulence closure model which incorporates an extra source term in the ε transport equation designed to increase the level of ε in nonequilibrium flow regions, thus reducing the kinetic energy and length scale magnitudes to improve prediction of adverse pressure gradient flows, including those involving separated flows regions. Two such cases are used here to test the model: one in the low speed flow regime, the other a supersonic one. Comparisons with experimental data and with an earlier version of the k-ε model, as well as with a variant of the k-ω model (both also wall-distance-free) reveal that the proposed model enables improved prediction of adverse pressure gradient flows relative to more traditional k-ε models.

Measurements of Molten Steel Surface Velocity and Effect of Stopper-rod Movement on Transient Multiphase Fluid Flow in Continuous Casting

“…The computational domain includes the nozzle and the liquid pool in the mold region, with the solidification front interface as the domain boundary. No-slip wall boundary condition is adopted both at the shell boundary and at the mold top surface, as the sintered slag layer serves as a solid wall, with an enhanced wall treatment (EWT) 34) to calculate near-wall velocities. Mass and momentum sinks are imposed at the layer of computational cells next to the shell boundary, to account for the liquid steel crossing the boundary due to solidification.…”

Navier-Stokes Computations for a Spinning Projectile from Subsonic to Supersonic Speeds

“…CFD++ also allows for turbulence modeling. For the study presented herein, the pointwise k-E (epsilon) turbulence model [9] was used.…”

Variational Multiscale LES and Hybrid RANS/LES Parallel Simulation of Complex Unsteady Flows

“…The boundary treatment is the same as for the VMS-LES simulations in Section 4, except that wall laws are now used. The RANS model is that based on the low-Reynolds approach [8]. The LES closure is based on the VMS approach (see Section2.1).…”

“…As far the closure of the RANS equations is concerned, the low Reynolds k − ε model proposed in [8] is used.…”

“…They are based on the ratios between (i) two eddy viscosities and (ii) two characteristic length scales. The RANS model used in the proposed hybrid approach is a lowReynolds version [8] of the standard k − ε model, while for the LES part the Variational Multiscale approach (VMS) is adopted [9]. In this paper, we present VMS-LES and RANS/LES parallel simulations of bluffbody flows, by a computational fluid dynamics (CFD) software which combines mesh partitioning techniques and a domain decomposition method.…”