School of Mechanical Engineering Professor Gennady Mishuris

School of Mechanical Engineering Seminar
Monday, June 25, 2018 at 14:00
Wolfson Building of Mechanical Engineering, Room 206

Shear stress induced by a fluid on the surface of a hydraulically driven crack.

Energy release rate in hydraulic fracture: Should or should not one take the phenomenon of the shear stress into account?

Professor Gennady Mishuris
Royal Society Wolfson Research Merit Award Holder
Department of Mathematics, IMPACS, Aberystwyth University
http://www.aber.ac.uk/en/maths/staff-list/staff_profiles/?login=ggm 

The talk consists of two parts.

In the first one, we briefly overview recent advance in the mathematical and numerical modelling of Hydraulic Fracture leading to an explicit level set algorithm based in particular on the accurate accounting for the solution asymptotics.

Then, in the second part, we discuss a novel HF model which accounts for the hydraulically induced shear stresses at the crack faces. It utilizes a general form of the elasticity operator alongside a revised fracture propagation condition based on the critical value of the energy release rate. 

We show that the revised formulation is always in agreement with the linear elastic fracture mechanics. We show that the phenomenon may play a significant role in the case of so-called small toughness and viscosity dominated regimes while in the other regimes it provides the analogous result as the classic model. We have also found that the small toughness regime should be no longer considered as a computational challenge. Finally, in those regimes, predicted crack redirection angle may change dramatically in comparison with the classic approach. We believe that the modified formulation opens new ways to analyse the physical phenomenon of HF, as well as improving the reliability and efficiency of its numerical simulation (our numerical simulations have already highlighted advantages of the model).