Publications
Connecting continuum poroelasticity with discrete synthetic vascular trees for modeling liver tissue
A. Ebrahem, E. Jessen, M.F.P. ten Eikelder, T. Gangwar, M. Mika, D. Schillinger
Abstract:
Computational simulations have the potential to assist in liver resection surgeries by facilitating surgical planning, optimizing resection strategies, and predicting postoperative outcomes. The modeling of liver tissue across multiple length scales constitutes a significant challenge, primarily due to the multiphysics coupling of mechanical response and perfusion within the complex multiscale vascularization of the organ. In this paper, we present a modeling framework that connects continuum poroelasticity and discrete vascular tree structures to model liver tissue across disparate levels of the perfusion hierarchy. The connection is achieved through a series of modeling decisions, which include source terms in the pressure equation to model inflow from the supplying tree, pressure boundary conditions to model outflow into the draining tree, and contact conditions to model surrounding tissue. We investigate the numerical behaviour of our framework and apply it to a patient-specific full-scale liver problem that demonstrates its potential to help assess surgical liver resection procedures.
Modeling of Growth using an Immersed Finite Element Method
Adnan Ebrahem, René R Hiemstra, Stein KF Stoter, Dominik Schillinger
Abstract:
To prevent remeshing, we explore the use of a non‐boundary‐fitted finite element method for the computational modeling of growth including contact mechanics. Accordingly, we utilize a mesh‐related mapping procedure for the use of implicit geometry description by a level set function within the framework of immersed methods. Hence, our framework provides a setting to include patient‐specific geometries based on imaging data as we use a level set function for the implicit geometry description. In this contribution, we show that the proposed approach is a viable alternative for problems with mesh‐related obstacles, in particular when large growth simulations on complex patient‐specific geometries are of primary interest.
Modellierung des elektromechanischen Reibkontaktes zwischen Finger und Touchscreen zur gezielten Erzeugung taktiler Effekte
- Heß M., Ebrahem A., Popov V.L., 60th German Tribology Conference, 2019.
Zusammenfassung:
Durch taktile Rückmeldung an den Benutzer kann die Leistungsfähigkeit berührungsempfindlicher Touchscreens erheblich gesteigert werden. Trotz umfangreicher experimenteller Untersuchungen sind die zugrunde liegenden Prinzipien bis heute noch nicht ausreichend verstanden und eine verlässliche Modellierung fehlt. Wir stellen ein vielversprechendes Modell für den elektromechanischen Reibkontakt vor, welches unter anderem die bekannten klassischen Theorien der molekularen Adhäsion ausnutzt.
Abstract:
By tactile feedback to the user, the performance of touch-sensitive screens can be significantly increased. Despite extensive experimental investigations, the underlying principles are still not sufficiently understood and reliable modeling is lacking. Therefore, we present a promising model for electroadhesive frictional contacts, which exploits, among other things, well-known classical theories of molecular adhesion.