An Improved Scale-Adaptive Simulation Model for Massively Separated Flows

Abstract

A new hybrid modelling method termed improved scale-adaptive simulation (ISAS) is proposed by introducing the von Karman operator into the dissipation term of the turbulence scale equation, proper derivation as well as constant calibration of which is presented, and the typical circular cylinder flow at Re = 3900 is selected for validation. As expected, the proposed ISAS approach with the concept of scale-adaptive appears more efficient than the original SAS method in obtaining a convergent resolution, meanwhile, comparable with DES in visually capturing the fine-scale unsteadiness. Furthermore, the grid sensitivity issue of DES is encouragingly remedied benefiting from the local-adjusted limiter. The ISAS simulation turns out to attractively represent the development of the shear layers and the flow profiles of the recirculation region, and thus, the focused statistical quantities such as the recirculation length and drag coefficient are closer to the available measurements than DES and SAS outputs. In general, the new modelling method, combining the features of DES and SAS concepts, is capable to simulate turbulent structures down to the grid limit in a simple and effective way, which is practically valuable for engineering flows.

Validation of Bluff-body Swirling Flame with RANS Turbulent Model and Comparison of the Results with LES Turbulent Model

“…The transport equations and algorithm of the model are explained in the following section of the chapter. Also, the details of the turbulence model can be found in the literature [34].…”

Review of tidal turbine wake modelling methods

“…An improved scale-adaptive simulation (ISAS) method has been developed. The ISAS method replaces the grid size turbulence length scale method used in DES with the second order term (von Karman) used in scale-adaptive simulation (SAS) [72]. The result is more efficient than SAS and without the grid sensitivity of DES.…”