NUMERICAL-SIMULATION OF VISCOELASTIC FLOW AROUND A CYLINDER USING AN INTEGRAL CONSTITUTIVE EQUATION

Numerical simulations have been undertaken for the flow of a 5 wt. % p olyisobutylene (PIE) solution in tetradecane (C14) around a cylinder p laced between parallel plates. The PIE solution has been the subject o f an extensive theological characterization and the flow geometry corr esponds to the one used in a previous study for laser Doppler anemomet ry and flow-induced birefringence measurements. The constitutive equat ion used is an integral-type K-BKZ model with a relaxation spectrum, w hich fits well experimental data for the shear and elongational viscos ities and the normal stresses as measured in shear flow. Stable numeri cal solutions have been obtained and used to compare the K-BKZ model p redictions with the experimental data reported recently by Baaijens. T he velocity and shear stress values predicted by the simulation are in excellent agreement with the experimental ones. Very good agreement i s also obtained for the predictions of the first normal stress differe nce both before and after the cylinder, in sharp contrast with previou s experimental results, which had shown a much slower relaxation of th e stresses. The drag force exerted by the fluid on the cylinder has be en calculated and reported to be a decreasing function of the Deborah number De. (C) 1995 Society of Rheology.