Currently, I am simulating a simple straight microchannel heat sink. I would like to compared with the established correlation which provides estimation of the pressure drop across the channel. According to previous published articles, the microchannel (usually there is about 10 channels or more than that in the heat sink) can be simulated just using a single channel instead of the entire channel to save computational time. I have studied different cases as below

1. Single channel microchannel heat sink

Only one channel for fluid flow and the other two side is wall. Symmetry boundary condition is

applied.

2. Single wall microchannel heat sink

The wall is situated in the middle, while the other two side is fluid. Symmetry boundary

condition is applied. As attached in the picture below.

My question is, when I use single channel, the pressure drop is about 7800 Pa, for single wall, the pressure drop is about 8900 Pa, while the estimated pressure drop from correlation is about 10000 Pa. Hence, in here, I would like to know whether single channel assumption is not valid. Hopefully anyone doing research study in this field can provide your advice.