When the flow in a minichannel passes around a bend, secondary flows can develop which can affect the flow, pressure drop and heat transfer rate in the bend and in the flow upstream and downstream of the bend. In order to investigate these effects in more detail attention has been given to flow in a simple minichannel system in which the flow enters the system with a uniform velocity and temperature and passes through a straight channel that has a length that is 10 times the size of the channel. The flow then passes around a rounded 180° bend. Following the bend, the flow passes down another straight channel which also has a length of 10 times the size of the channel. A uniform heat flux is applied over the entire surface of the channel. The channel has a trapezoidal cross-sectional shape. It has been assumed that the flow is steady and incompressible and that there is no slip at the channel walls. The governing equations have been written in dimensionless form and solved using a commercial finite-element based software package, FIDAP. The solution has the following parameters: the Reynolds number, the Prandtl number, the dimensionless radius of the bend and the ratio of the bottom-to-top widths of the channel. Results will only be presented for a Prandtl number 0.7 for Reynolds numbers of between 10 and 500 for various dimensionless bend radii and various bottom-to-top channel width ratios. The major concern in this work is with the extent of the influence of the secondary flow on the flow in the straight channel sections upstream and downstream of the bend. The effect of the channel shape and of the dimensionless channel corner radius on the pressure distributions and on the dimensionless wall temperature distributions, in the straight channel sections in particular, have been considered.

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