Alternative Approach to Modelling the Dissipation Equation

Abstract

Direct numerical simulations show that even for simple equilibrium flows the models of major interactions in the transport equation for turbulence energy dissipation $\\varepsilon = v\overline {(\partial {u_i } /\partial {x_l } )^2 }$ do not adequately reflect the corresponding terms in the exact ε equation. This is particularly pronounced in low-Re-number flow regions where the dynamics of dissipative correlation is strongly affected by viscosity and vicinity of a solid wall. The success in reproducing ε reasonably well, even at low-Re-numbers and near walls is achieved by ad hoc tuning of the equation as a whole, concealing the compensating errors in term-by-term modelling. Hence, the application of the models in non-equilibrium situations, different from ones in which the models were calibrated, leads often to unsatisfactory performances.