Flow and Heat Transfer in a Square Minichannel With Rounded Corners

Incompressible flow through a minichannel with a basically square cross-section has been considered. It is often assumed that rounding the comers in such a channel has a significant effect on the pressure drop and heat transfer rate. In order to investigate whether this is in fact the case, attention has been given to flow in a channel in which two adjacent corners are rounded, the radius of the two corners being the same. The other two corners of the channel are not rounded. The effect of the radius of the corners of the duct on the pressure losses, on the losses associated with the developing flow near the duct entrance and on the Nusselt number has been numerically studied. It has been assumed that the flow is steady, that the flow is incompressible, that the velocity and temperature are uniform over the channel inlet plane, and that there is no slip on the boundaries. A uniform heat flux is assumed to be applied over the entire surface of the duct. The governing equations have been written in dimensionless form. Solutions to these dimensionless governing equations have obtained using a commercial finite-element software package, FIDAP. The solution has the following parameters: the Reynolds number, Re, the Prandtl number, Pr, and the dimensionless radius of the corners of the duct bend R = r_c / w, where w is the width and height of the channel and r_c is the radius of the rounded edges of the duct. Results have been obtained for Pr = 0.7 for Re values between 10 and 1000 and R values between 1/6 and 1/3.