粘弾性流体の抵抗低減乱流における応力方程式モデルの圧力歪相関項

抄録

The prediction of the turbulent flow of a viscoelastic fluid is required for engineering applications. We applied a Reynolds stress model proposed (for Newtonian fluid) by Hanjalic & Jakirlic (1998). This model can predict a turbulent flow in a Newtonian fluid with precision. In the viscoelastic turbulence, we should model an additional nonlinear term of fluctuating strain and conformation tensor in the ensemble-averaged constitutive equation. In the present model of the nonlinear term, we investigated the model parameters in order to adjust them to the adopted background Reynolds stress model aiming at a better prediction of the mean velocity profile. The present model can predict mean velocity profile better than earlier model by Leighton et al. (2003). The optimal values of model parameters were found to depend on either the friction Reynolds number or Weissenberg number. The relationships between the model parameters and flow parameters are formulated. Moreover, we tried introducing a viscoelastic pressure strain term, since the anisotropy of the Reynolds normal stress is significant character in the drag-reducing flow.