Authors Dimakopoulos Y., Pavlidis M., Tsamopoulos J. Abstract The steady, buoyancy-driven rise of a bubble in a Herschel-Bulkley fluid is examined assuming axial symmetry. The variation of the rate-of-strain tensor around a rising bubble necessitates the coexistence of fluid and solid regions in this fluid. In general, a viscoplastic fluid […]
Viscoplastic Fluids
6 posts
Authors Dimakopoulos Y., Tsamopoulos J. Abstract We study the transient displacement of Newtonian and viscoplastic liquids by highly pressurized air in cylindrical tubes of finite length with an expansion followed by a contraction in their cross section. Papanastasiou’s formula is employed to regularize the discontinuous Bingham model. For both fluid […]
Authors Karapetsas G., Tsamopoulos J. Abstract The transient, axisymmetric squeezing of viscoplastic materials under creeping flow conditions is examined. The flow of the material even outside the disks is followed. Both cases of the disks moving with constant velocity or under constant force are studied. This time-dependent simulation of squeeze […]
Authors Dimakopoulos Y., Tsamopoulos J. Abstract We examine the transient displacement of a viscoplastic material from straight or suddenly constricted cylindrical tubes of finite length. Our general goal is to develop accurate and efficient numerical methods for the fundamental study of processes in which a gas is displacing a liquid […]
Authors Smyrnaios D.N., Tsamopoulos J.A. Abstract The axisymmetric squeeze flow of viscoplastic materials is examined using either the original Bingham constitutive equation or the approximate model suggested by Papanastasiou. Previous theoretical analyses of this problem, using the standard lubrication approximation, have led to conflicting results, whereby the material around the […]
Authors Tsamopoulos J.A., Chen M.F., Borkar A.V. Abstract The spin coating of a viscoplastic material is studied using a continuous viscosity function. Thus, the transient model requires the calculation of only velocity, pressure and the moving-free surface of the liquid film, but not the calculation of the yield surface within […]