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12.6 The $v^2$- $f$ Model Theory

The $v^2$- $f$ model is similar to the standard $k$- $\epsilon$ model, but incorporates near-wall turbulence anisotropy and non-local pressure-strain effects. A limitation of the $v^2$- $f$ model is that it cannot be used to solve Eulerian multiphase problems, whereas the $k$- $\epsilon$ model is typically used in such applications. The $v^2$- $f$ model is a general low-Reynolds-number turbulence model that is valid all the way up to solid walls, and therefore does not need to make use of wall functions. Although the model was originally developed for attached or mildly separated boundary layers [ 92], it also accurately simulates flows dominated by separation [ 31].

The distinguishing feature of the $v^2$- $f$ model is its use of the velocity scale, $\overline{v^2}$, instead of the turbulent kinetic energy, $k$, for evaluating the eddy viscosity. $\overline{v^2}$, which can be thought of as the velocity fluctuation normal to the streamlines, has shown to provide the right scaling in representing the damping of turbulent transport close to the wall, a feature that $k$ does not provide.

For more information about the theoretical background and usage of the $v^2$- $f$ model, please visit the Fluent User Services Center.

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