Generalized coutte flow of herschel-bulkley fluid through eccentric annulus-an approximate solution

Seyidoğlu, Tijen
Generalized Couette flow of a Herschel-Bulkley fluid in an eccentric annulus is analyzed by approximating the flow geometry as a slit of variable height. Besides an imposed pressure gradient, one of the plates is considered non-stationary to take into account the axial and/or angular motion of the inner pipe in an eccentric annulus system. Depending on the magnitude and the direction of the applied pressure gradient with respect to the plate velocity, three separate flow cases are studied in which the velocity reaches its maximum value either within the plug flow region or at the moving boundary. Velocity distributions are obtained for each case by solving the equations of continuity and motion. Volumetric flow rate expressions are obtained by integrating the velocity distribution over the cross-sectional area. At a given pressure gradient, the results indicate an increase in volumetric flow rate with an increase in eccentricity ratio. Criteria for each flow type is developed in terms of a dimensionless parameter ?, which takes into account the ratio of the imposed pressure gradient to the plate velocity. Volumetric flow rate expressions for Newtonian, Bingham and power-law fluids are obtained by considering the limiting values of the fluid index and yield stress. The validity of the equations are checked by considering the slit height to be a constant, i.e., flow between parallel plates. Surge/swab pressure calculations are carried out for Herschel-Bulkley, power-law and Bingham fluids and the results are expressed as a function of eccentricity ratio, radius ratio, fluid index and yield stress. The results indicate that when the fluid index and the eccentricity ratio are fixed, a slight increase in the radius ratio causes a tremendous increase in surge/swab pressure, especially for low values of fluid index. On the other hand, displacement of the inner pipe from a


An empirical method for the second viral coefficients of non-standard fluids
Kis, Konrad; Orbey, Hasan (Elsevier BV, 1989-9)
A new empirical method is proposed for the extension of Pitzer-Curl type correlations of the second virial coefficient to non-standard fluids as define
A study on the effect of pipe - soil relative stiffness on the behaviour of buried flexible pipes
Bircan, Mehmet; Özkan, M. Yener; Department of Civil Engineering (2010)
In this study, the effect of pipe-soil relative stiffness on the behaviour of buried flexible pipes was investigated considering the pipe size, material type, stiffness, pipe-soil and natural soil-backfill interfaces and geometry of the trench using the finite element method. For this purpose, a parametric study was conducted to examine the effect of different variables on the resulting earth loads and deformations imposed on the buried pipes. Various types of trench pipe-soil cases were analysed for a cert...
AKKAS, N; Tokdemir, Turgut (Elsevier BV, 1992-08-03)
Consider a partial differential equation with cylindrical coordinates describing a dynamic process in an infinite medium with an inner cylindrical boundary. If an analytical solution to the problem is not possible, then one resorts to numerical techniques. In this case it becomes necessary to discretize the infinite domain even if the solution is required on the inner cylindrical surface or at a limited number of points in the domain only. The residual variable method (RVM) circumvents the difficulty associ...
The simplest cubic equation of state for low-pressure vapor—liquid equilibrium calculations
Orbey, H; VERA, JH (Elsevier BV, 1990)
A simple, virial-like cubic equation of state has been developed from the general form of the perturbed hard core model. The equation simultaneously incorporates saturation liquid volume and saturation pressure information for pure compounds. With two adjustable parameters per binary, it can represent low-pressure vapor—liquid equilibria as well or better than dual methods. This model applies a single equation to both phases and necessitates only a fraction of the input information required by dual methods....
Gürkan, Türker (Informa UK Limited, 1989-6)
The equations of motion for the flow of a power-law fluid sphere in a Newtonian continuous phase have been approximately satisfied by Galerkin's method: External and internal stream functions have been obtained for the following ranges of variables: 10-50 for Re0, 0.1-1000 for the viscosity ratio parameters, X, and 0.6-1.0 for the dispersed phase power-law index, ni,. It is predicted that pseudoplasticity in the dispersed phase causes a reduction in the circulation within the drop and that it has a minor ef...
Citation Formats
T. Seyidoğlu, “Generalized coutte flow of herschel-bulkley fluid through eccentric annulus-an approximate solution,” M.S. - Master of Science, Middle East Technical University, 2006.