eddy viscosity

eddy viscosity

[‚ed·ē vi′skäs·əd·ē]
(fluid mechanics)
The turbulent transfer of momentum by eddies giving rise to an internal fluid friction, in a manner analogous to the action of molecular viscosity in laminar flow, but taking place on a much larger scale.
References in periodicals archive ?
Taking consideration of local eddy-viscosity and near wall behaviours, the wall-adapting local eddy viscosity model is used.
According to the Boussinesq eddy viscosity assumption (Boussinesq, 1877), the logarithmic law for velocity profile was solved by using the mixing length method (Prandtl, 1925; Khan et al.
s] is the damping function of the SGS eddy viscosity near the wall created by van Driest.
1999: Subgrid-scale parameterizations of eddy-topographic force, eddy viscosity and stochastic backscatter for flow over topography.
Classical turbulence models based on the Reynolds decomposition (RANS) with an eddy viscosity model lead to a calculated turbulent viscosity up to a hundred times higher than that suitable for resolving turbulent structures important for detailed in-cylinder flow analyses [6].
A dynamic subgrid-scale eddy viscosity model," Physics of Fluids A3, 1760 (1991), doi:10.
The k - [epsilon] model, like the zero equation model, is based on the eddy viscosity concept, so that:
The turbulence modeling community has responded by developing model equations of ever increasing complexity, ranging from the nonlinear eddy viscosity models where the Reynolds stress is nonlinearly related to the mean rate of strain, to the full Reynolds-stress transport models where each component of the Reynolds stress is governed by its own transport equation (able to resolve secondary flows).
The eddy viscosity hypothesis assumes that Reynolds stresses can be related to mean velocity gradients and eddy (turbulent) viscosity by the gradient diffusion hypothesis in a manner analogous to the relationship between stress and strain tensors in laminar Newtonian flow:
Attempts have been made to overcome the inconsistency between the recorded data and Ekman theory by using numerical modelling including the depth-varying eddy viscosity (Madsen 1977; Huang 1979) and by complementing the physical background of the Ekman layer description with dynamic processes like the buoyancy flux, Stokes drift, etc.
Thus, it was not very surprising to see the good performance of these eddy viscosity models.