The effect of the hydrodynamic interaction on the rheological properties of Hookean dumbbell suspensions in steady state shear flow

1987 ◽  
Vol 8 (9) ◽  
pp. 829-838
Author(s):  
Fan Xi-jun
Keyword(s):  
Steady State ◽  
Shear Flow ◽  
Rheological Properties ◽  
Hydrodynamic Interaction

Experimental Methods for Measurement of the Rheological Properties of Polymeric Fluids

2007 ◽  
Author(s):  
Chang Dae Han
Keyword(s):  
Steady State ◽  
Shear Flow ◽  
Rheological Properties ◽  
Viscoelastic Fluids ◽  
Experimental Methods ◽  
Flow Properties ◽  
Concentric Cylinder ◽  
Polymeric Fluids ◽  
Rheological Measurements ◽  
Oscillatory Shear Flow

There has been a continuing interest in developing experimental techniques for the measurement of the rheological properties of viscoelastic fluids. As discussed in Chapter 3, reliable experimental data are needed in order to evaluate the effectiveness of a constitutive equation in its ability to predict the rheological properties of viscoelastic fluids. Also, as is presented in later chapters, a better understanding of the rheological properties of polymers is very important for the determination of optimum processing conditions, as well as for the attainment of desired physical/mechanical properties in the finished product. Further, reliable measurement of the rheological properties of polymers can be used to control polymerization reactors in industry and also to control polymer processing operations. In this chapter, we present experimental methods for measurement of the rheological properties of polymeric fluids. For this, we discuss experimental methods to determine (1) steady-state simple shear flow and oscillatory shear flow properties using cone-and-plate rheometry, (2) steady-state shear flow properties using capillary/slit rheometry, and (3) elongational flow properties of polymeric fluids. There are other rotational types of rheological instruments, such as those with concentric-cylinder and eccentric-parallel plates. However, such rheological instruments are not widely used today and thus in this chapter we do not present the principles and applications of such rheological instruments. In presenting the experimental methods for rheological measurements we refer to the fundamentals presented in Chapters 2 and 3. For further details of the experimental methods, there are monographs (Collyer and Clegg 1998; Dealy 1982; Ferry 1980; Walter 1975) that are devoted entirely to the discussion of rheological measurements. The primary purpose of this chapter is to demonstrate how the fundamentals presented in Chapters 2–4 can be used in the measurement of the rheological properties of polymeric fluids. Optical rheometry is an important experimental technique for investigation of the relationship between any microphase morphology dynamics and the rheological behavior of complex polymeric fluids (e.g., liquid-crystalline polymers), which exhibit strong chain orientation during flow (Fuller 1995).

Theory of hydrodynamic interaction of two spheres in wall-bounded shear flow

2020 ◽  
Vol 5 (5) ◽  
Author(s):  
Itzhak Fouxon ◽  
Boris Rubinstein ◽  
Zhouyang Ge ◽  
Luca Brandt ◽  
Alexander Leshansky
Keyword(s):  
Shear Flow ◽  
Hydrodynamic Interaction

Numerical study of electric field effects on the deformation of two-dimensional liquid drops in simple shear flow at arbitrary Reynolds number

2009 ◽  
Vol 626 ◽  
pp. 367-393 ◽  
Author(s):  
STEFAN MÄHLMANN ◽  
DEMETRIOS T. PAPAGEORGIOU
Keyword(s):  
Steady State ◽  
Shear Flow ◽  
Electric Field ◽  
Electric Fields ◽  
Simple Shear ◽  
Simple Shear Flow ◽  
Physical Parameters ◽  
Shear Stresses ◽  
Two Dimensional ◽  
Liquid Drops

The effect of an electric field on a periodic array of two-dimensional liquid drops suspended in simple shear flow is studied numerically. The shear is produced by moving the parallel walls of the channel containing the fluids at equal speeds but in opposite directions and an electric field is generated by imposing a constant voltage difference across the channel walls. The level set method is adapted to electrohydrodynamics problems that include a background flow in order to compute the effects of permittivity and conductivity differences between the two phases on the dynamics and drop configurations. The electric field introduces additional interfacial stresses at the drop interface and we perform extensive computations to assess the combined effects of electric fields, surface tension and inertia. Our computations for perfect dielectric systems indicate that the electric field increases the drop deformation to generate elongated drops at steady state, and at the same time alters the drop orientation by increasing alignment with the vertical, which is the direction of the underlying electric field. These phenomena are observed for a range of values of Reynolds and capillary numbers. Computations using the leaky dielectric model also indicate that for certain combinations of electric properties the drop can undergo enhanced alignment with the vertical or the horizontal, as compared to perfect dielectric systems. For cases of enhanced elongation and alignment with the vertical, the flow positions the droplets closer to the channel walls where they cause larger wall shear stresses. We also establish that a sufficiently strong electric field can be used to destabilize the flow in the sense that steady-state droplets that can exist in its absence for a set of physical parameters, become increasingly and indefinitely elongated until additional mechanisms can lead to rupture. It is suggested that electric fields can be used to enhance such phenomena.

Determination of Thermal Conductivity of Soils: A Need for Computing Heat Loss Through Buried Submarine Pipelines

1982 ◽  
Vol 22 (04) ◽  
pp. 558-562 ◽  
Author(s):  
P.C. Rawat ◽  
S.L. Agarwal
Keyword(s):  
Thermal Conductivity ◽  
Steady State ◽  
Crude Oil ◽  
Rheological Properties ◽  
Heat Loss ◽  
Experimental Results ◽  
Dry Density ◽  
Empirical Relationships ◽  
Thermal Conductivities

Abstract An important parameter required for computing heat loss through buried submarine pipelines transporting crude oil is the thermal conductivity of soils. This paper describes an apparatus designed for determination of the thermal conductivity of soils at the desired moisture/ density condition in the laboratory under steady-state conditions. Experimental results on the three soils studied show that thermal conductivity increases as dry density increases at a constant moisture content and that it increases as water content increases at constant dry density. These results confirm the trends isolated earlier by Kersten. The experimental results are compared with the available empirical relationships. Kersten's relation is observed to predict the thermal conductivity of these soils reasonably. The predictions from Makowski and Mochlinski's relation (quoted by Szilas) are not good but improve if the sum of silt and clay fractions is treated as a clay fraction in the computation. Introduction Submarine pipelines are used extensively for transporting crude oil from offshore to other pipelines offshore or onshore. These pipelines usually are steel pipes covered with a coating of concrete. They often are buried some depth below the mudline. The rheological properties of different crude oils vary, and their viscosities increase with a decrease in temperature. Below some temperature, the liquid oil tends to gel. Therefore, for efficient transportation, the crude must be at a relatively high temperature so that it has a low viscosity. The temperature of the soil/water system surrounding a submarine pipeline is usually lower than that of oil. This temperature difference induces heat to flow from the oil to the environment, and the temperature of the oil decreases as it travels along the length of the pipeline. One must ensure that this temperature reduction does not exceed desirable limits dictated by the rheological properties of oil and by the imperatives of efficient economic properties of oil and by the imperatives of efficient economic transportation. Thus the analytical problem is to predict the temperature of crude in the pipeline some distance away from the input station. To do so, knowledge of the overall heat transfer coefficient for the pipeline is required, for which, in turn, it is necessary to know the thermal conductivities of the oil, the pipeline materials and its coating, and the soil. This paper presents thermal conductivities of soils determined in the laboratory under steady-state conditions and also presents a comparison of the test results of three soils with values determined from existing empirical relationships. Literature Review Heat moves spontaneously from higher to lower temperatures. In a completely dry porous body, transmission of heat can take place not only by conduction through the solid framework of the body and the air in the pores but also by convection and radiation between the walls of a pore and by macro- and microdistillation. In soils, however, it can be ascribed essentially to conduction, a molecular phenomenon that can be expressed in terms of experimentally determined coefficients of conductivity or resistivity, although these actually may include microdistillation and other mechanisms. SPEJ p. 558

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