Date of Award
Master of Engineering
Mechanical and Materials Engineering
Prof. Roger E. Khayat
The symmetric two-dimensional flow of a thin viscoelastic fluid jet emerging from a vertical channel is examined theoretically in this study. The fluid is assumed to be a polymeric solution, modeled following the Oldroyd-B constitutive equation. The influence of inertia, elasticity and gravity in the presence of surface tension is investigated for steady flow only. Special emphasis is placed on the initial stages ofjet development. The viscoelastic boundary-layer equations are solved by expanding the flow field in terms of orthonormal shape functions. In contrast to the commonly used depth-averaging technique, the proposed method predicts the shape of the free surface, as well as the velocity and stress components within the fluid. It was found that the jet reaches the same uniform thickness regardless of Reynolds number in the absence of gravity. However, the distance to reach the uniform thickness depends on inertia. Presence of gravity enhances the jet contraction and leads to possible jet break up. Presence of surface tension tends to prohibit the contraction and flatten the jet surface. In contrast to the Newtonian flow, viscoelastic flow displays uniform flow much farther from the channel exit. Swelling is observed as Deborah number increases. The velocity and stress components profiles suggest that elasticity tends to play different role to inertia. Surface tension tends to flatten the jet surface similar to the Newtonian jet, but the stress components are not affected much in the case of a viscoelastic jet. The numerical solution is validated with experiment and good qualitative agreement is achieved.
Ahmed, Moinuddin, "STEADY FLOW OF A THIN VISCOELASTIC JET" (2011). Digitized Theses. 3524.