Laminar entrance flow in curved annular ducts
Abstract
Steady laminar flows in coiled annular ducts are investigated numerically. Solutions are obtained by solving the incompressible NavierStokes equation with a SIMPLEtype procedure for annular curved ducts of various radius ratios for a given Reynolds number. The effect of radius ratio on flow development is given particular attention. Computational results indicate that the secondary flow in a half cross section (above or below the line of symmetry) for the case of moderate radius ratio is characterized by a pair of counterrotating vortices; the flow in the core region moves toward the outside bend, and the flow near the inner and outer walls moves toward the inside bend. However, when the radius ratio is very large, say greater than 0.8, the secondary flow is unidirectional and moves toward the inside bend. When the radius ratio is moderate the centroid of the first moment of streamwise velocity lies on the outside half plane. The flow in a curved annular duct is not necessarily fully developed earlier when the radius ratio is larger owing to the complicated interaction between the viscous and the centrifugal forces.
 Publication:

International Journal of Heat and Fluid Flow
 Pub Date:
 March 1992
 Bibcode:
 1992IJHFF..13...41C
 Keywords:

 Annular Ducts;
 Duct Geometry;
 Laminar Flow;
 NavierStokes Equation;
 Steady Flow;
 Centrifugal Force;
 Flow Equations;
 Incompressible Flow;
 Reynolds Number;
 Viscous Flow;
 Fluid Mechanics and Heat Transfer