Some influences of particle shape on drag and heat transfer

Abstract

A study has been carried out on some of the influences of particle shape and orientation on the drag, lift, and heat transfer characteristics of nonspherical particles at intermediate Reynolds numbers, 10≤Re≤66. The geometry that has been employed in the investigation has been an ellipsoid of revolution with variation in angle of attack, and the aspect ratio (ratio of the major to the minor axis) has been varied by a factor of 3. The method of solution consists of a second-order, finite volume formulation of the Navier–Stokes equations, which is capable of being extended to time-dependent and variable density low Mach number flows. For relatively small increases in the ratio of major to minor axis the behavior of the pressure and skin friction distributions becomes substantially different in both qualitative and quantitative ways. The skin friction distribution as well as the heat flux to the particle surface exhibit a maxima near the major axis of the ellipsoid regardless of orientation, and the total friction drag and the total particle heat transfer exhibit a strong correlation. The total drag coefficient and the lift coefficient behave in a much different manner and they are strongly influenced by the Reynolds number, aspect ratio, and angle of attack. It appears that the total drag and lift force depend strongly on the particle shape, and it appears difficult to develop simple correlation schemes. The numerical methods that have been used performed well and they will be extended to more complex problems in the future.