A strain parameter turbulence model and its application to homogeneous and thin shear flows

Refined Eddy Viscosity Schemes and Large Eddy Simulations for Ascending Mixed Convection Flows

“…6(c): the CI model is in close agreement with the data (fully-developed channel and pipe flows having supplied some of the 'target' data used in tuning the model; Cotton and Ismael [1998]); however, the At the moderate buoyancy influence of Fig. 7 there is no appreciable distortion of the velocity and temperature profiles.…”

“…All those authors used various forms of two-equation closure and a finding to emerge from the studies taken together was that the 'lowReynolds-number' model of Launder and Sharma [1974] was generally superior to the other variants examined. Cotton et al [2001] compared the Launder-Sharma scheme against the threeequation closure of Cotton and Ismael [1998]; the present work includes an examination of the Launder-Sharma and Cotton-Ismael models. Researchers in the field have also evaluated other strategies: for example, Richards et al [2004] and Kim et al [2006] report some success in applying the ' f v 2 − ' model of Durbin [1991] to turbulent mixed convection flows.…”

“…' Cotton and Ismael [1998] argued that a fundamental weakness exists in the stress/rate-of-strain relationship of high-Reynolds-number EVMs. Thus, for example, one might consider the constitutive equation of the 'standard' ε − k model [Launder and Spalding, 1974]: under the influence of simple shear, the structural ratio k uv / − as determined by this model varies linearly with the group…”

“…Three different CFD codes have been employed in the study: 'CONVERT', 'Code_Saturne', and 'STAR-CD', which are respectively inhouse, industrial, and commercial packages. In general, forced convection flows are best resolved by the LES computations and Cotton-Ismael turbulence model (Cotton and Ismael [1998]). In mixed convection flows the picture changes and the Launder-Sharma closure [Launder and Sharma, 1974] and 'Manchester f v 2 − ' model [Keshmiri et al, 2008] are in closest agreement with the direct simulation heat transfer data.…”

Assessment of a common nonlinear eddy-viscosity turbulence model in capturing laminarization in mixed convection flows

“…Although no profile was reported for ε by You et al, none of the profiles shown in Figure 4b are expected to be in good agreement with the DNS data especially near the wall, due to highly approximate nature of the ε-equation [30]. The differences between the predictions of LS and Suga models seen in Figure 4b are partly associated with different definitions of the "E-term" in the ε-transport equations of the models (compared in Table 2).…”