Effects of the Geometry Scale on the Behaviour of the Local Physical Process of the Velocity Field in the Laminar Flow

It is well known that the convective terms in the equation of fluid motion play an outstanding role on the local proprieties of flows and they affect the local behaviour of physical processes such as deformation, rotation, stretching and folding. Large values of these processes in the flow have pronounced and lasting effects on the improvement of heat transfer and fluid mixing in ducts. The modification of the geometric scale presents an easy and adequate solution to increase these parameters. For this purpose, three dimensional zigzag channels with hydraulic diameters equal to 5 mm, 10 mm and 20 mm were examined in this study. Evolutions of the deformation rate, rotation rate and the stretching/compression coefficients of the vortices were examined for different values of the Reynolds number in three dimensional laminar open flow, using a CFD code. The results illustrate that the geometry with the smallest hydraulic diameter is the more favourable to increase the considered parameters.