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The lifting Hele-Shaw cell (LHSC) is used to study adhesion as well as viscous fingering. In the present paper we report a series of observations of development of the interface for different viscous fluids, both Newtonian and non-Newtonian, in a LHSC operated at a constant lifting force. Glass and perspex are used as the plates in two different sets of experiments. The objectives are 1) to measure the time required to separate the plates as a function of the lifting force and 2) to note the force above which viscous fingering appears. We find that for the Newtonian fluids, the plate separation time follows a universal power law with the lifting force, irrespective of fluid and substrate. The non-Newtonian fluids too, with proper scaling obey the same power law. The appearance of fingering, however, depends on the properties of the fluid as well as the substrate. We suggest a modified form of the capillary number which controls the onset of fingering; this new quantity, termed the "fingering parameter" involves the dielectric constants of the substrate and fluid in addition to the viscosity and surface tension.

[1] Experimental studies show that porous sedimentary rocks have a fractal pore-grain interface. The bidisperse ballistic deposition model (BBDM) generates a porous structure by computer simulation. The model is able to reproduce the behavior of several macroscopic properties of sedimentary rocks quite well. In the present paper we show that the microstructure of the pore space created in BBDM is also realistic. Two-point correlations of the pore space agree qualitatively with results for real rocks, and the sample spanning pore has a fractal dimension in the range 2.29-2.99 for different porosities. We also study diffusion in the pore space by a random walk and show that it is anomalous at low porosities.