A novel analytical method predicts plug boundaries of bingham plastic fluids for laminar flow through annulus

Abstract

In Bingham plastic fluids, a central pre-yield or plug region exists in the middle of the concentric annular flow. In this region, the local shear stress is less than the dynamic yield stress, so the plug behaves like a rigid solid. This is the main feature that distinguishes the flow of a Bingham plastic fluid from that of a power law fluid. In this work, a simple-to-use correlation is developed to predict the boundaries of the plug of Bingham plastic fluids for laminar flow through annulus as a function of dimensionless yield stress and aspect ratio parameters for given values of the rheological constants, pressure gradient and the dimensions of the annulus. The results are found to be in excellent agreement with reported data in the literature with an average absolute deviation of less than 1.7%. The predictive tool is simple and straightforward and can be readily implemented in a standard spreadsheet program. The prime application of the method is as a quick-and-easy evaluation tool in engineering studies where plug boundaries of Bingham plastic fluids for laminar flow through annulus are being considered. The method may also serve as a benchmark in numerical and rigorous simulation studies.

Fluid dynamics study of the flow and pressure drop analysis of a non‐Newtonian fluid through annular ducts with unusual cross‐sections

“…N on-Newtonian fluids flowing in pipes and annular ducts are found in industries that deal with slurries and suspensions, as in oil and gas drilling operations. [1][2][3] Such applications require a detailed understanding of the flow in order to improve the process performance. [4] In the oil industry, it is very important to know the fluid dynamics of the drilling fluid to assure proper cleaning of the well (transport of the cuttings to the surface by the drilling fluid), reduce the effective costs of the process (required pump pressure and consequent flow rate), and ensure operation safety (kick detection and control).…”

“…Non‐Newtonian fluids flowing in pipes and annular ducts are found in industries that deal with slurries and suspensions, as in oil and gas drilling operations . Such applications require a detailed understanding of the flow in order to improve the process performance .…”

Systematic investigation of asphaltene precipitation by experimental and reliable deterministic tools

“…Solving the system of the corresponding equations, the coefficients of the polynomial function (e.g. Equation ), , are determined . Solving the V matrix is dependent on the unisolvence theorem.…”

“…One of the efficient ways not to deal with computationally expensive systems of equations is utilization of the Lagrange interpolation technique. If the total number of data points is (n + 1), the Lagrange polynomial is n‐degree as shown below: …”