Secondary Flow Effects in a Trapizoidal Minichannel Flow System Involving Two Straight Sections Separated by a 180° Bend

Patrick H. Oosthuizen
2007 ASME 5th International Conference on Nanochannels, Microchannels, and Minichannels   unpublished
When the flow in a minichannel system passes around a bend, secondary flows develop and flow separation can also occur in the bend both of 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 this, attention has been given to flow in a simple such system. In the system considered the channels have a trapezoidal crosssection with parallel top and bottom surfaces. The flow enters the channel with a
more » ... 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 sharp 90 o bend, flows through a short straight channel and then flows through another sharp 90 o bend. Following the two bends, the flow passes down another straight channel which also has a length 10 times the size of the channel. A uniform temperature exists over the entire surface of the channel. 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. Solutions to these dimensionless governing equations have been obtained using a commercial finite-element software package, FIDAP. The solution has the following parameters: the Reynolds number, the Prandtl number, the dimensionless length of the straight pipe section between the two bends and the ratio of the bottom-totop widths of the channel. Results have been obtained for a Prandtl number 0.7 for Reynolds numbers of between 100 and 5000 for various values of the other dimensionless parameters.
doi:10.1115/icnmm2007-30072 fatcat:hol7k4rlljbppef37e7tnhlpyi