Transient displacement of Newtonian and viscoplastic liquids by air in complex tubes

On the elliptic mesh generation in domains containing multiple inclusions and undergoing large deformations

“…For optimizing the quality of the mesh, constraints (e.g. generalized node distributions) along specific surfaces of the geometry were imposed, alleviating in this way the stiffening of the scheme when exponential attractive terms are used in the elliptic equations [13,17]. Another improvement that was incorporated herein is a local refinement algorithm, for increasing the resolution of the mesh along the free surfaces while keeping the computation cost as a low as possible.…”

On the transient coating of a straight tube with a viscoelastic material

“…The quasi-elliptic method to generate the computational mesh in control volumes that exhibit large deformations has been successfully applied in steady state (Tsamopoulos et al [42]) and transient calculations (Foteinopoulou et al [43]; Karapetsas and Tsamopoulos [44]; Dimakopoulos and Tsamopoulos, [4,[16][17][18][19][20][21]). It incorporates the three important characteristics of the gridlines: smoothness, orthogonality and optimized gridline concentration.…”

“…These are inherently time-dependent processes where the bubble is formed and then gets elongated by applying a constant, very high pressure, all taking place in a very short time. Hence, Dimakopoulos and Tsamopoulos [4,[16][17][18][19][20] have made a systematic effort to simulate numerically the transient displacement of Newtonian as well as viscoplastic and viscoelastic fluids in straight or complicated tubes for a large range of geometric and physical parameters. Motivated by the need to simulate accurately and efficiently the GAIM process, in which the domain occupied by the liquid is not only a-priori unknown as in all the previous reports under steady state, but evolves in time, they developed a body-fitted mesh-generating scheme (Dimakopoulos and Tsamopoulos [21]).…”

Steady Flow of a Two-Dimensional Liquid Curtain Under Pressure

“…The two sides of the rectangular finite elements are vertical, and thus the more the liquid curtain deviates from the x-axis, the more distorted the elements become. A different approach, such as the quasi-elliptic mesh-generating scheme for moving boundary and free-surface problems developed by Dimakopoulos and Tsamopoulos (2007), must, therefore, be employed in order to extend the range of convergence of the method.…”