Viscoelastic sink flow in a wedge for the UCM and Oldroyd-B models

The steady planar sink flow through wedges of angle pi/alpha with alpha >= 1/2 of the upper convected Maxwell (UCM) and Oldroyd-B fluids is considered. The local asymptotic structure near the wedge apex is shown to comprise an outer core flow region together with thin elastic boundary layers at the wedge walls. A class of similarity solutions is described for the outer core flow in which the streamlines are straight lines giving stress and velocity singularities of O(r(-2)) and O(r(-1)). respectively, where r << 1 is the distance from the wedge apex. These solutions are matched to wall boundary layer equations which recover viscometric behaviour and are subsequently also solved using a similarity solution. The boundary layers are shown to be of thickness O(r(2)), their size being independent of the wedge angle. The parametric solution of this structure is determined numerically in terms of the volume flux Q and the pressure coefficient p(0). both of which are assumed furnished by the flow away from the wedge apex in the r = O(1) region. The solutions as described are sufficiently general to accommodate a wide variety of external flows from the far-field r = O(1) region. Recirculating regions are implicitly assumed to be absent. (c) 2008 Elsevier B.V. All rights reserved.