Laminar - turbulent transition in the propagation of height contained hydraulic fracture

High injection rate hydraulic fracturing can have Reynolds number as high as 10000. For such high Reynolds numbers, turbulent flow is likely to occur. In this paper, we investigate the effect of turbulence on the propagation of hight contained hydraulic fractures, commonly referred to as PKN fractures. We discuss different scalings for the fracture width, length and pressure under limiting laminar, turbulent smooth and turbulent rough flow regimes. We implement an explicit, central numerical scheme to solve the continuity and friction factor based momentum conservation equations, taking into account the full variation of friction factor with Reynolds number and relative fracture roughness. The scheme is validated against the analytical solution of the PKN model. The results show that the local Reynolds number evolves from a maximum value at the inlet to zero at the tip, with a transition from turbulent to laminar at some point along the fracture length, depending on the value of inlet Reynolds number. Results showing the effect of smooth and rough turbulence on the fracture length and fracture width depending on the Reynolds number are finally presented.