The numerical investigation on extrudate swell through capillary die forviscoelastic fluid characteried by integral-type Maxwell constitutive equation was conducted byemploying the finite element method with the calcu...The numerical investigation on extrudate swell through capillary die forviscoelastic fluid characteried by integral-type Maxwell constitutive equation was conducted byemploying the finite element method with the calculation of viscoelastic extra stress in theconventional finite element. The method of avoiding singularity was also adopted by integrating thestrain history of the Gauss points for each element near the wall and the free surface. Theconvergence solutions at high Weissenberg number can be obtained by using the appropriate methods toreduce errors and improve the speed of convergence of the calculation, which include adding arelaxation factor of velocity in iteration process, or enlarging the reference viscosity, orreducing the elapsed time. The highest Weissenberg number obtained here is up to 3. 8, while thesolution at the Weissenberg number of 3. 75 was given in the previous work with similar extrudateswell ratio and the exit pressure drop by using differential Maxwell model with Elastic-ViscousStress Split (EVSS) combined with Streamline Upwind Petrov-Galerkin (SUPG) scheme. The calculationsindicated that the method of dealing with integral consti- tutive equation introduced in this paperis suitable in simulating viscoelastic flow characterized by integral constitutive equation at highe-lastic level.展开更多
文摘The numerical investigation on extrudate swell through capillary die forviscoelastic fluid characteried by integral-type Maxwell constitutive equation was conducted byemploying the finite element method with the calculation of viscoelastic extra stress in theconventional finite element. The method of avoiding singularity was also adopted by integrating thestrain history of the Gauss points for each element near the wall and the free surface. Theconvergence solutions at high Weissenberg number can be obtained by using the appropriate methods toreduce errors and improve the speed of convergence of the calculation, which include adding arelaxation factor of velocity in iteration process, or enlarging the reference viscosity, orreducing the elapsed time. The highest Weissenberg number obtained here is up to 3. 8, while thesolution at the Weissenberg number of 3. 75 was given in the previous work with similar extrudateswell ratio and the exit pressure drop by using differential Maxwell model with Elastic-ViscousStress Split (EVSS) combined with Streamline Upwind Petrov-Galerkin (SUPG) scheme. The calculationsindicated that the method of dealing with integral consti- tutive equation introduced in this paperis suitable in simulating viscoelastic flow characterized by integral constitutive equation at highe-lastic level.
