An in-situ measurement technique to determine the rheology of a fluid based on the experimentally measured velocity profile of a flow in a mini-channel is introduced. The velocity profiles of a Newtonian and different shear-thinning fluids along a rectangular channel were measured using shadowgraph particle image velocimetry (PIV). Deionized water and different concentrations of a polyacrylamide solution were used as Newtonian and shear-thinning fluids, respectively and were studied at different Reynolds numbers. The flow indices of the fluids were determined by comparing the experimental velocity profile measurements with developed theory that takes into account the non-Newtonian nature of the fluids rheology. The results indicated that the non-Newtonian behavior of the shear-thinning fluid intensified at lower Reynolds numbers and it behaved more as a Newtonian fluid as the Reynolds number increased. A comparison between the power law index determined from experimental monitoring of the velocity profile at different Reynolds numbers and measurements from a rheometer reflected good agreement. The results from the study validate the new approach of the rheology measurement of Newtonian and non-Newtonian flows through straight, rectangular crosssection channels. The proposed approach can be further utilized using other methods such as X-ray PIV to characterize the rheology of non-transparent fluids and in general, for all non-Newtonian fluids.
Combined free and forced convection flow of a viscous incompressible electrically conducting fluid in a rotating channel is studied. Analytical solution for the velocity and induced magnetic field is obtained in closed form. Asymptotic behavior of the solution for the velocity and induced magnetic field is analyzed for large values of magnetic parameter M 2 and rotation parameter K 2 to gain some physical insight into the flow pattern. The expressions for the shear stress and critical Grashof number at both the plates and mass flow rates are also derived. Numerical values of rate of heat transfer at both the plates are obtained with the help of MATLAB software. The numerical values of velocity and induced magnetic field are displayed graphically whereas that of shear stress at the upper plate, mass flow rate, critical Grashof number and rate of heat transfer at both the plates are presented in tabular form for various values of flow parameters.
Pore-scale velocity measurements can be achieved by using micro particle shadow velocimetry (µ-PSV). Characteristic properties of a flow are, however, best investigated and described by the pressure distribution in the field. At the pore scale, applying direct pressure measurement techniques comes with significant challenges. By detailed measurement of velocity and applying theoretical relations that suit the flow field under study, the pressure field can be determined. This study demonstrates the application of image-based approaches to investigate the multi-phase flow of a single droplet. Experiments based on µ-PSV are used to determine the velocity field in the flow within the droplet as it passes through a single-pore geometry in the presence of a stationary continuous phase. The results are used to determine the pressure field calculated from a simplified Navier–Stokes expression of the flow, discretised using an Eulerian approach. For the dispersed phase, the theory of the Jamin effect allows the capillary pressure to be related to the observed change in radii of the leading and trailing edges of the droplet. To highlight this approach, two sizes of the glycerol droplets passing through a pore geometry in the presence of a stationary canola oil are investigated. The results show that the velocity and pressure distributions are dictated by the deformation properties of the droplet. The same trends are seen in the distribution of pressure and velocity gradients as a function of location along the channel. The larger of the two droplets showed increased levels of velocity and pressure gradients as it flows through the pore geometry. In general, this work demonstrates the use of the deformation behavior of a dispersed phase to determine the velocity and pressure distributions in a multi-phase flow field.
Summary Studies that investigate and attempt to model the process of steam-assisted gravity drainage (SAGD) for heavy-oil extraction often adopt the single-phase-flow assumption or relative permeability of the moving phases as a continuous phase in their analyses. Looking at the emulsification process and the likelihood of its prevalence in SAGD, however, indicates that it forms an important part of the entire physics of the process. To explore the validity of this assumption, a review of prior publications that are related to the SAGD process and the modeling approaches used, as well as works that studied the emulsification process at reservoir conditions, is presented. Reservoir conditions are assessed to identify whether the effect of the emulsion is strong enough to encourage using a multiphase instead of a single-phase assumption for the modeling of the process. The effect of operating conditions on the stability of emulsions in the formation is discussed. The review also covers the nature and extent of effects from emulsions on the flow mechanics through pore spaces and other flow passages that result from the well completion and downhole tubing, such as sand/flow-control devices. The primary outcome of this review strengthens the idea that a multiphase-flow scenario needs to be considered when studying all flow-related phenomena in enhanced-oil-recovery processes and, hence, in SAGD. The presence of emulsions significantly affects the bulk properties of the porous media, such as relative permeability, and properties that are related to the flow, such as viscosity, density, and ultimately pressure drop. It is asserted that the flow of emulsions strongly contributed to the transport of fines that might cause plugging of either the pore space or the screen on the sand-control device. The qualitative description of these influences and their extents found from the review of this large area of research is expected to guide activities during the conception stages of research questions and other investigations.
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