Drag coefficient axial

Fig. 6.4 Drag coefficients for axial flow past spheroids. Numerical predictions of Masliyah (M4).

In a recent work, Aiba (A2) studied the flow currents in water, in a mixing vessel 14 in. in diameter, using an axially-mounted two-bladed flat paddle 4.7 in. in diameter. Measurements were made both without baffles and with four baffles %2 tank diameter wide. A sphere about 6 mm. in diameter was suspended by a flexible wire, and its displacement from the equilibrium (no-flow) position was measured. To get the horizontal displacement, cobalt-60 was embedded in the sphere, and a Geiger-Mueller counter approximately 10 mm. in diameter was immersed in the tank 2-5 cm. from the sphere. The vertical movement of the sphere was measured with a cathetometer, and its angular position observed by eye. From the known components of displacement and the assumed drag coefficient of the sphere, values of the radial, tangential, and vertical components of the flow around the sphere were calculated. 

In axial flow past disks, which are the limit cases of axisymmetric bodies of small length, the drag coefficients are given in [94] for the entire range of Reynolds numbers calculated with respect to the radius. These formulas approximate numerical results and experimental data ... 

Unnikrishnan and Chhabra (1990) Cylinders (axial) lA L/d) 2 Power law Experimental results on wall effects and drag coefficient in creeping flow region... 

Chhabra (1992) Cylinders (axial) 1.4 (L/d)<2 Power law Results on wall effects and drag coefficients up to Re 20... 

Venu Madhav and Chhabra (1994) Cylinders (axial) and prisms 0.35 Power law (0.77 < n < 1) Extensive results on wall factors and drag coefficient in the range 0.05 < Re <150... 

In recent years, the axial sedimentation of thin cylinders and needles in GNFs has received renewed impetus from the standpoint of falling needle viscometry and to an extent from the wire-coating applications. Thus, Manero et al. (1987) analyzed the inertialess motion of a thin rod at the axis of a cylinder filled with incompressible power-law fluid. For the case when the size of the cylinder is much larger than that of the needle d D = X the drag coefficient, = 2FlndLpV ) is given by... 

In 1970, Uhlherr and Sinclair (see Brucato et al, 1998) found an increase of the drag coefficient for spheres as a result of free-stream turbulence, at least at higher values of the turbulence intensity T = u /v in which stands for the root mean square of the turbulent fluctuations in the fluid s axial velocity. Uhlherr and Sinclair considered the pressure difference between nose and wake as well as the position of the boundary layer separation which shifts toward the back of the particle due to the free-stream turbulence. Their correlations are given by... 

Experimental data and numerical results for principal values of the translational tensor for some axisymmetric and orthotropic bodies (cylinders, doubled cones, parallelepipeds) were discussed in [94], It was established that the results are well approximated by the following dependence for the relative coefficient of the axial drag ... 

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