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Institut für Allgemeine Mechanik Univ.-Prof. Dr.-Ing. Bernd Markert __________________________________________________________________________

Vortragsankündigung

Prof. Dr.-Ing. Wolfgang Ehlers Institut für Mechanik (Bau) / EXC SimTech

Universität Stuttgart IAM, Raum 112 • 29.06.2015 • 15:30 Uhr

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Simulation-Technology-Based Solutions of Coupled Problems in Continuum Mechanics

Continuum Mechanics usually considers the theoretical and computational description of standard single-phasic materials in the framework of either solid mechanics, fluid mechanics or gas dynamics. However, growing complexity in material modelling combined with the request of users leads to a growing interest in porous-media mechanics, where porous solid materials with fluid or gaseous pore content are investigated on a macroscopic scale.

Within this framework, the contribution contains the theoretical and numerical framework for the description of geomechanical and biomechanical problems including elastic, elastoplastic and viscoelastic solid behaviour partly combined with electro-active properties, the coupling phenomena of porous solids with pore fluids, no matter if the fluids have to be treated as inert fluids or fluid mixtures.

The numerical procedure is embedded in the PANDAS software, where PANDAS is either used as the solver or as a numerical tool coupled to powerful solvers like Abaqus. Various computational examples are presented to illuminate the possibilities and challenges of porous-media mechanics.

Peer Review Only

FLUID-POROUS-MEDIA INTERACTION BY LOCALISED LAGRANGE MULTIPLIERS 29

t = 0.02 s t = 0.50 s t = 1.00 s

{uMy , uSy} [mm]

Liquid

subsystem

Porou

smed

ium

subsystem

0.0−0.9

Figure 13: Snapshots showing the responses of the subsystems at selected times. The arrowsrepresent the bulk-fluid velocity vL and the pore-fluid velocity vF within the subsystems.

to the bulk-fluid velocity on the inlet VI and the outlet II.

There, the upper row depicts the results for the bulk-fluid and the lower row representsthe response of the porous-medium subdomain. Considering this, the arrows demonstrate thedirections of the bulk-fluid velocity vL and the pore-fluid velocity vF within the subdomains.Furthermore, the contours of the vertical mesh deformation uMy and solid skeleton deformationuSy are shown. Studying these results reveals an agreement between the response calculatedby the code and the predicted behaviour of the system as presented at the beginning of thissection. Moreover, the conformity between the fluid mesh motion and that of the solid skeletoncan be well seen. Figure 14 demonstrates a better representation of this conformity.

For a more precise investigation, the calculated variables at sample interface positions A(at x = 2m , y = 10m), B (at x = 5m , y = 10m) and C (at x = 8m , y = 10m) have beenextracted. Subsequently, the evolution of the interaction forces (the Lagrange multipliers), aswell as that of the interface velocities of the bulk fluid vintL , of the pore fluid vintF and of the solidskeleton vintS have been monitored. The results are shown in Figures 15 and 16, respectively.

Looking at these diagrams shows that at time t = 0.01 s, the interface forces are equal tozero, see Figure 15. This is due to the fact that at this time, the bulk-fluid and the porous-

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