화학공학소재연구정보센터
Journal of Non-Newtonian Fluid Mechanics, Vol.165, No.9-10, 527-537, 2010
Re-entrant corner behaviour of the PTT fluid with a solvent viscosity
The local asymptotic behaviour is given for planar re-entrant corner flows of Phan-Thien-Tanner fluids with a solvent viscosity. The solvent stress and Newtonian velocity field dominate in all regions, with the polymer stress being uniformly subdominant. At small radial distances r to the corner, the velocity field vanishes as O(r(lambda 0)) whilst the solvent stress behaviour is O(r(-(1-lambda 0))). The polymer stress has the less singular behaviour O(r(-4(1-gamma 0)/(5+lambda 0))), where lambda(0)is an element of[1/2.1) is the Newtonian flow-field eigenvalue. Stress boundary layers are needed at the walls for the polymer stress solution, which are of thickness O(r((4-lambda 0)/3)). These results confirm the order of magnitude estimates previously obtained by Renardy [14], the alternative derivation given here using the method of matched asymptotic expansions. Further, we complete previous analysis by providing solutions (particularly for the polymer stresses) in the asymptotic regions that arise. These results breakdown in the limit of vanishing solvent viscosity as well as the Oldroyd-B model limit. (c) 2010 Elsevier B.V. All rights reserved.