Herschel–Bulkley fluid

About: Herschel–Bulkley fluid is a research topic. Over the lifetime, 1946 publications have been published within this topic receiving 49318 citations.

New conception in continuum theory of constitutive equation for anisotropic crystalline polymer liquids

Abstract: A new continuum theory of the constitutive equation of co-rotational derivative type is developed for anisotropic viscoelastic fluid—liquid crystalline (LC) polymers. A new concept of simple anisotropic fluid is introduced. On the basis of principles of anisotropic simple fluid, stress behaviour is described by velocity gradient tensor and spin tensor instead of the velocity gradient tensor in the classic Leslie—Ericksen continuum theory. Analyzing rheological nature of the fluid and using tensor analysis a general form of the constitutive equ- ation of co-rotational type is established for the fluid. A special term of high order in the equation is introduced by author to describe the sp- ecial change of the normal stress differences which is considered as a result of director tumbling by Larson et al. Analyzing the experimental results by Larson et al., a principle of Non- oscillatory normal stress is introduced which leads to simplification of the problem with relaxation times. The special behaviour of non- symmetry of the shear stress is predicted by using the present model for LC polymer liquids. Two shear stresses in shear flow of LC polymer liquids may lead to vortex and rotation flow, i.e. director tumbling in the flow. The first and second normal stress differences are calculated by the model special behaviour of which is in agree- ment with experiments. In the research, the com- putational symbolic manipulation such as computer software Maple is used. For the anisotropic viscoelastic fluid the constitutive equation theory is of important fundamental significance.

Influence of wall properties on the peristaltic motion of a herschel-bulkley fluid in a channel

Abstract: Peristaltic motion of a Herschel-Bulkley fluid in a two-dimensional channel with wall effects is studied. Assuming that the wave length of the peristaltic wave is large in comparison to the mean half width of the channel, a perturbation method of solution is obtained in terms of wall slope parameter, under dynamic boundary conditions. Closed form expressions are derived for the stream function and average velocity and the effects of pertinent parameters on these flow variables have been studied. It has been observed that the time average velocity decreases with yield stress and power law index. Further, the time average velocity increases with rigidity in the wall. It has been observed that trapping occurs and the size of the trapped bolus increases with power-law index.

Exact solutions for oscillating motion of a second-grade fluid along an edge with mixed boundary conditions

Abstract: Exact solutions corresponding to the oscillating motion of a second-grade fluid along the inside of an edge are established by means of integral transforms. The motion of the fluid is due to the walls of the edge. One of them applies an oscillating shear to the fluid and the other one is subject to an oscillatory motion in its plane. The solutions that have been obtained are presented in the form of simple and multiple integrals and satisfy all imposed initial and boundary conditions. Finally, some characteristics of the fluid motion, as well as the influence of Reynolds number on the velocity, are graphically underlined.

MoS2 Nanoparticle Effects on 80 °C Thermally Stable Water-Based Drilling Fluid

Abstract: Bentonite-based drilling fluids are used for drilling, where inhibitive fluids are not required. The rheological and the density properties of the drilling fluids are highly affected by high temperature and pressure. Due to high temperature, the clay particles stick together, and the fluid system becomes more flocculated. Poorly designed drilling fluid may cause undesired operational issues such as poor hole cleaning, drill strings sticking, high torque and drag. In this study, the 80 °C thermally stable Herschel Bulkley’s and Bingham plastic yield stresses drilling fluids were formulated based on lignosulfonate-treated bentonite drilling fluid. Further, the impact of a MoS2 nanoparticle solution on the properties of the thermally stable base fluid was characterized. Results at room temperature and pressure showed that the blending of 0.26 wt.% MoS2 increased the lubricity of thermally stable base fluid by 27% and enhanced the thermal and electrical conductivities by 7.2% and 8.8%, respectively.